WO2010094658A1 - Monitoring of tiltable mirrors - Google Patents

Abstract

The present invention relates to a device and a corresponding method for monitoring the orientation of at least one mirror (4), in particular a plurality of mirrors in a mirror field, such as can be used in a projection exposure system for microlithography. According to the invention, a detection device (1) for detecting the light reflected by the mirror is provided, wherein a pattern source (2) is disposed, which can provide a pattern (3) with space- and/or time-variable light sources, said pattern being mirrored by the at least one mirror on the detection device. The orientation of the mirror can be determined based on the mirrored image detected by the detection device.

Description

 MONITORING OF TILTING MIRRORS

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The present invention relates to a device and a method for monitoring or determining the orientation or positioning of at least one mirror, in particular a plurality of mirrors with a detection device for detecting the reflected light from the mirror or mirrors and a projection exposure apparatus in which such a device and a corresponding method can be used.

STATE OF THE ART

In microlithography projection exposure systems, systems requiring light wavelengths in the vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) range are being increasingly developed due to the required resolution of increasingly smaller structures. These systems contemplate the use of so-called Micro Mirror Arrays MMA's (Micro Mirror Panels) having a plurality of small tiltable mirrors with a number of up to several million mirrors for setting flexible illumination. However, micromechanical or microelectromechanical units with adjustable mirrors are also used in projection exposure systems which use other wavelengths of light.

These adjustable, usually by one or two z. B. perpendicular to each other oriented axes tiltable mirror must be set defined in their orientation, so that a corresponding monitoring of the orientation or a regulation of the orientation of the mirror, in which the actual positioning as an input parameter enters the scheme, are necessary.

Accordingly, there are already considerations as to how the monitoring of corresponding mirrors can be realized. For example, it has been proposed by illuminating the mirror with a separate measuring radiation in addition to the working light of the projection exposure apparatus and corresponding detection of the reflected light, the orientation of the To determine the mirror. Examples of this are described in German Patent Application DE 10 2007 005 875 A1 or WO 2008/09695 A2. However, a corresponding device requires complex optics and sensors in order to be able to determine the orientation of the mirrors.

In addition to the expenditure on equipment, the required measurement time also plays an essential role for the effective monitoring of the mirror positions in order to be able to form rapidly switchable and dynamic systems.

DISCLOSURE OF THE INVENTION

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide an apparatus and a method for monitoring the orientation or positioning of at least one mirror, preferably a plurality of mirrors in a mirror array, in which the position of the mirror can be detected quickly and effectively and wherein the corresponding device easy to produce and easy to operate. In addition, the device and the corresponding method should ensure sufficient accuracy of the position detection.

TECHNICAL SOLUTION

This object is achieved by a device having the features of claim 1 and a corresponding method, as described below. Subject is also a projection exposure system for microlithography, in which the corresponding method and apparatus are used. Advantageous embodiments are the subject of the following description and / or the dependent claims.

The present invention is unlike the previous approaches, which perform only an analysis and evaluation of the reflected light to determine the position of the mirror, to provide already on the lighting side no homogeneous illumination of the mirror or mirrors, but to provide a pattern which or the mirror is imaged into a corresponding detection device. The pattern can be spatial and / or temporally variable light sources, so that in particular with knowledge of the original pattern, a comparison of the mirrored light with the original pattern and / or the detection and evaluation of the light reflected on the mirrors or the light of the pattern allows conclusions about the orientation of the mirror.

The pattern source providing the corresponding pattern can be realized in different ways. For example, it is conceivable that the pattern is printed on a sheet of paper or other support, such as a screen, or displayed on a screen or monitor, such as a TFT screen or the like. In addition, a plurality of individual separate bulbs in a corresponding arrangement produce a pattern. Here, for example, light emitting diode arrays (LED arrays) or other structures with corresponding bulbs are conceivable. Accordingly, therefore, the pattern may be formed by active light sources and / or by passive light sources, in which illumination light is reflected only correspondingly. Thus, for the purposes of the present application, the term light source is any single point of a surface-extending pattern which emits light to be reflected on the mirror (s) to be monitored. Of course, in extreme cases, the emitted light intensity can also drop to or at least near a zero value, so that no light is reflected.

The term light is generally used as a term for electromagnetic radiation.

The patterns used in the present invention have different light sources over the pattern surface, so that correspondingly spatially variable or different light sources result, which ultimately produce the corresponding pattern.

In addition to a spatial distribution of different light sources for generating a pattern, it is also possible to provide a temporal variability of the light sources or a change in the light sources, with the result that the pattern changes over time. This is particularly possible in the representation of the patterns by screens or active light sources and the like.

The basic principle of the present invention is that due to the given pattern corresponding to the mirror position different, mirrored images or Light intensities of the mirrored pattern in a detection device for detecting the reflected light from the mirror are detectable. Due to the dependence of the detected, reflected by the mirror light from the mirror position, can be deduced in particular with knowledge of the output pattern on the mirror position. Alternatively, a corresponding pattern also gives the possibility to monitor mirror movements based on changes in the detected light and to deduce the position and / or orientation of the mirror from the tracking of the mirror movement. By mirroring a pattern, the evaluation of the reflected light becomes easier or more effective and the position and / or orientation of the mirror can be more accurately determined compared to homogeneous illumination methods. Here, the terms position, orientation and orientation are used interchangeably and generally define that the unique three-dimensional determination of the arrangement at a maximum of 6 degrees of freedom of movement is meant. With a smaller number of degrees of freedom of movement, for example the possibility of tilting only about one axis, only the tilt angle is accordingly meant, so that this too is used interchangeably for position and orientation.

In particular, a corresponding evaluation unit, in particular a plurality of automated evaluation units, preferably based on electronic data processing, can be provided for the analysis or evaluation of the reflected light, which information is acquired from the information about the original pattern to be mirrored and / or the information collected by the detection device , reflected light can determine an absolute or relative position of the mirror or mirrors.

In this case, the detection device can be formed by or include various devices, such as one or more black-and-white cameras with or without color filters, one or more color cameras or sensors based on these digital cameras, such as charge coupled device CCDs, CMOS (Complementary metal oxide semiconductor) sensors (complementary metal oxide semiconductor sensors) or photodiodes in general. The selection of a corresponding detection device depends on the exact configuration of the corresponding measuring device and the measuring method.

For example, according to a first embodiment, the pattern-based monitoring method or system can be configured so that only the light intensities differ. the light sources of the pattern with respect to one or more specific mirrors are evaluated to determine an absolute position of the mirror or mirrors. In such an embodiment, the detection device, for example in the form of a camera, may have an optical system that is prepared so that the mirror or mirrors to be monitored are imaged sharply into the image area of the detection device, ie the camera is focused on the mirrors. Accordingly, the defined image from mirror to detection device is achieved, in particular, by focusing a camera on the mirrors so that the mirror or mirrors are clearly imaged in the detection device. This ensures that each mirror is assigned a defined image area of the camera. This means that one or more pixels of a corresponding image sensor defined are associated with a mirror of, for example, a plurality of mirrors of a mirror field. By determining measured values for the detected light intensities in the image area of spatially different light sources of the pattern, the corresponding absolute position of the mirror can be determined. For example, a plurality of light sources of a pattern area, which is mirrored by a mirror onto a defined image area of the detection device, can illuminate successively. This means that the spatially different light sources of the pattern with constant mirror orientation in the predetermined image area of the detection device generate different light intensities due to the different geometrical conditions, even if the spatially different light sources have the same light intensities. From these measured values, the orientation of the mirror can then be determined at least with respect to the tilt about two axes of rotation.

For such an approach, instead of spatially different light sources with the same wavelength of light or same wavelength range and same or different radiation intensity, which are only switched sequentially, find a pattern in which are used as spatially different light sources with different wavelengths of light or wavelength ranges. For example, light-emitting diodes can be used in a light-emitting diode array which emit light in the green light wavelength range, in the blue light wavelength range and in the red light wavelength range. When using a color camera or a plurality of black-and-white cameras with corresponding color filters, the corresponding intensities in the detection device can be determined for the differently colored light sources, so that again distinguishable measured values are present. Correspondingly, they can be for the locally different light sources determine the data collected by the detection device for the reflected light and thus calculate the mirror position.

According to a second embodiment of the present invention, instead of calculations on the basis of the determined light intensities, a direct pattern matching can also take place. This means that an assignment of the mirrored pattern or the mirrored pattern, i. H. the image or images in the detection device, to the original pattern, whereby the determination of the orientation or positioning of the mirror is possible by the corresponding assignment. In this second embodiment variant, therefore, it is particularly important that the pattern in the image of the detection device is recognizable. Accordingly, a detection device, such as a camera, can be set with the corresponding optics so that the pattern can be sharply imaged. Consequently, according to this variant, it is possible to focus on the pattern to be mirrored, or the optics are adjusted such that both the mirror or mirrors and the pattern to be mirrored are sharply imaged. Accordingly, it is also possible to focus on an intermediate area. In order to enable a sharp imaging of both mirrored patterns and mirrors in the detection device, a sufficiently high depth of field for sharply imaging the object space, ie the mirror and the specular pattern, can be provided in the optics of the detection device.

According to both embodiments, the detection device may be configured such that only one detection point of the detection device, that is, for example, a pixel of the camera, is assigned to a mirror, so that the detection point for the respective mirror detects the reflected light. Thus, the presented monitoring system is well suited for monitoring a plurality of mirrors, since the number of mirrors to be monitored is limited only by the number of pixels of the detector or in a simple manner, a high number of mirrors can be monitored.

In the following, the term pixel will be used interchangeably for a corresponding detection point of the detection device.

In addition, it is also possible for each mirror to have a plurality of pixels associated with the detection device, for example at least 9 pixels, preferably at least 16 pixels or most preferably 25 pixels. Thus, the corresponding resolution can be increased or certain patterns or pattern matching methods can be used.

The patterns provided by the pattern source and the corresponding pattern matching methods may be of different types. In addition to patterns with active and / or passive light sources, as already mentioned above, the patterns can have light sources with light of different wavelengths or wavelength ranges or light sources with light of the same wavelengths of light. For light sources having different wavelengths of light, the corresponding light sources may be associated with certain positions in the pattern or evenly distributed throughout the pattern. In particular, the radiation intensity of the light sources can vary over the pattern, with continuous or stepwise variation of the intensity being possible. In particular, the light sources can also be combined into corresponding groups together and in this case arranged in a sectoral manner in the pattern. In addition, a periodic, grid-like arrangement is conceivable. With a periodic arrangement of the light sources, an arrangement in accordance with a sine wave can be provided.

The corresponding design of the pattern with regard to the light intensity may relate to light sources with light of a single wavelength of light or of a range of light wavelengths (white light) or may be provided in each case for light sources of different wavelengths of light or wavelengths of light. In this case, in particular the changes of the pattern along the x and y directions of the pattern surface can be provided for one light wavelength or one light wavelength range, respectively. For example, the light intensity of a first wavelength, for example in the red frequency range, can be changed continuously or stepwise in the x-direction of the surface pattern, while in the y-direction the light intensity of a second wavelength range, for example of green light, is changed. The change here can be either a continuous or incremental increase or decrease in the light intensity or a periodic change, such as corresponding to a standing sine wave. In addition to a standing sine wave or other periodic changes, corresponding patterns that vary with time can also be used to realize corresponding waves that propagate through the pattern.

In particular, in addition to a direct pattern comparison between provided pattern and reflected pattern and the use of the influence of the reflection conditions on the change of the reflected pattern to the provided pattern for determining the tilt of a mirror can also be applied to the phase-measuring deflectometry, in which the phase of a periodic pattern, for example a sinusoidal or cosinusoidal intensity or brightness curve, in connection with the local and / or or temporal variation of the pattern is used to infer the angle of reflection and thus the orientation and orientation of a mirror used to mirror the pattern. The principle here is based on the fact that, depending on the tilt angle of the mirror, there is another reflection angle below which a region of the pattern is imaged in a detection device, for example a camera. In the case of a temporal and / or local change of the pattern or of the detection device, in the case of a plurality of measured values (acquisitions) or images in which the reflected pattern is detected, it is possible to calculate back what tilt orientation of the mirror is present. For this purpose, in the simplest case, a one-dimensional periodic gray scale profile, for example in a sine or cosine form, is sufficient. This can be generated in the pattern, for example by a TFT screen, first as an X-directional wave to determine an orientation or tilt of the mirror in the X direction, and then the periodic pattern in the Y direction can be displayed to determine a tilt in the Y direction.

Instead of the one-dimensional shape of the periodic pattern, which can run temporally variable in the manner of a wave over a screen on which the pattern is displayed, a two-dimensional phase-measuring deflectometry can be applied, in which, for example, a gray scale profile is present, in each case a sine wave or cosine patterns in the X and Y directions are superposed with each other.

In addition to the two-dimensional gray scale pattern with period in two independent spatial directions, ie X and Y direction, with brightness or intensity differences, the periodic patterns, such as sine and cosine curves, can also be generated with different wavelengths of light, so that, for example, in the X direction periodic pattern with green light and in Y-direction a periodic pattern with red light is generated. By a two-dimensional, phase-measuring deflectometry due to a two-dimensional Graustufernverlaufs or a corresponding two-dimensional color coding, the measurement time can be significantly reduced by simultaneous measurement of the X and Y tilting. For the evaluation in phase-measuring deflectometry, an equation system with several unknowns has to be solved. The prerequisite for this is that multiple acquisitions, that is to say images of the reflected pattern, are recorded in order to recalculate the tilt angles of the mirror from these recorded intensity progressions. For a two-dimensional phase-measuring defektometry with cosine curves in the independent spatial directions x and y, for example, five images (acquisitions) are required in order to be able to determine the orientation and position of the mirror. In addition to this first parameter, which stands for the number of required images (acquisitions) as well as for the different phases in a first direction, or the x-direction, a second parameter can be selected that covers the different phases in the second spatial direction , that represents the y-direction.

In order to be able to carry out a desired evaluation, it is advantageous to select the parameters in a suitable manner. For example, it is advantageous to select the number of images (acquisitions) higher than the minimum value in order to compensate for deviations introduced during the measurements due to inaccuracies in the pattern or the detection device. Thus, it is advantageous to choose a multiple of the minimum number of necessary images (acquisitions), the multiple lying in a small single-digit range for a multiplier, ie in particular in the range less than or equal to 10 or less than or equal to 3. For a one-dimensional phase-measuring deflectometry method, where the theoretical minimum of the acquisitions is three images, for example, 4, 6, 8 or 12 images could be selected. For example, in a two-dimensional method in which the minimum number of images (acquisitions) is 5, a larger number of images such as 8, 10, 16, or the like could be selected.

The second parameter can then be selected as a fraction of the first parameter, the value of the first parameter being present in the numerator and a corresponding integer in the denominator.

In the case of phase-measuring deflectometry, so-called phase deconvolution may also be used, in which a plurality of periodic patterns, for example cosine patterns, are superimposed. The phase-measuring deflectometry can also be used if the pattern is fixed in time, ie no corresponding wave runs over the pattern surface. Instead of the temporally variable pattern, a temporally invariable pattern can be used, which in turn has a one-dimensional or two-dimensional periodic pattern, but this time fixed. Instead of changing the pattern with time, in this embodiment, a plurality of locally differently arranged detection means are used, so that the different detection means the different phases in different areas of the periodic pattern can be detected according to the orientation of the mirror.

For this purpose, several detection devices can be arranged side by side.

However, instead of a plurality of detection devices, only a single detection device having a plurality of detection regions can be provided.

The generation of corresponding phase-shifting patterns can also be effected by the sequentially switched and / or superimposed representation of patterns.

For example, overlaid patterns that are not self-variable in time, e.g. suitable overlays of slide projections or the like can be used to generate corresponding phase-shifting patterns. In addition to the superimposition of slide projections or projectors and the like, the corresponding patterns can also be imaged, for example, with different colors firmly on a substrate and switched by irradiation with special light, such as complementary colors, polarized light or the like.

In addition, it is possible to generate corresponding patterns with corresponding illuminant fields, that is to say a number of lamps, in particular LEDs or the like, which can generate a phase characteristic by suitable switching of corresponding groups of the luminous means.

Another possibility is to illuminate a grid or a perforated plate or mask with a plurality of light sources, so that a corresponding pattern is formed on a diffuser arranged in front of the perforated plate or the grating or mask. By appropriate Switching the different light sources can then be generated on the diffuser again a phase-shifting pattern.

When using a color camera and different color filters in the individual holes of the perforated plate, the method can be refined accordingly, so that the ambiguity of a phase determination can be resolved via the color code and can be used, for example, for the coarse determination of the positioning of the mirror.

Furthermore, a pattern generating device can have a plurality of light sources with masks assigned to each light source, wherein the masks have corresponding patterns that are imaged by the light sources and any optics onto a projection screen or luminescent screen. Due to the superimposition and / or successive switching of the different patterns, correspondingly time-varying patterns can be generated on the projection screen or fluorescent screen. Such an arrangement may be particularly advantageous in projection exposure equipment in which the pattern should be placed in a vacuum chamber, since the generation of the pattern in a vacuum could be problematic and mirroring of an externally applied pattern through vacuum partitions is difficult to achieve. In a corresponding pattern generating means having a plurality of light sources, masks and optics for imaging the patterns of the masks on the projection or luminescent screen, the optics or parts thereof may be provided in the vacuum chamber partition so that the pattern per se with the projection screen is simply provided in the vacuum chamber can and mirror elements in vacuum chambers can be measured accordingly.

In this context, binary masks can also be used in connection with defocused imaging optics in order to generate patterns with, for example, sinusoidal or cosinusoidal progressions.

Another possibility for determining the position and / or orientation of the mirrors using periodic patterns, in particular patterns with cosine-shaped intensity or color gradients, is the use of optical incremental methods. In these, the position of the mirror is determined by monitoring the change in the mirror position, in which the displacement of the periodic pattern associated with mirror tilting in the detector is determined on the basis of the passing periods. telt. Using an index signal which may be provided in the pattern and which indicates a predetermined position, the absolute positions may also be determined by such methods.

The pattern may also be an arbitrary noise pattern or a randomly generated pattern, in particular for the second embodiment variant with a pattern recognition, such as surface areas of components in the vicinity of the mirrors to be monitored, e.g. painted or textured surfaces of the housing of a projection exposure system or the like.

In the event that active light sources of the pattern are switched into groups, adjacent groups can be switched so that they are not switched simultaneously in order to avoid mutual interference or interference.

For passive light sources, e.g. printed patterns or surface textures, additional illumination, in particular only temporary illumination for the time of the measurement acquisition, e.g. be provided by flashing lights or the like.

The patterns can also be imaged by imaging devices in the vicinity of the mirror to be monitored, if this makes it necessary, for example, lack of space.

For pattern matching, d. H. The comparison of the pattern imaged in the detection device with the original pattern can be carried out using different methods of image or pattern recognition or comparable methods, in particular correlative methods.

If the position of the mirror is already close to a desired target value, a gradient-based motion estimation can also be used for the measurement, that is to say for comparison of the mapped and original pattern, eg. When using noise patterns. Gradient-based motion estimation is described in addition to correlative methods eg in Jahne: Digital Image Processing, 4th Edition, Chapter 13, Springer Verlag. In the second embodiment variant with the pattern comparison, a translatory movement or an offset of the mirrors can lead to a measurement error that can be compensated by a second camera. In the case of curved mirrors, the curvature of the mirrors can also be used to compensate for such translatory movements. The background is that the mirror curvature with just one camera results in almost two or more views of the same object (here mirror or mirrored pattern detail). A simple thought model is, for example, the modeling of a curved mirror as two plane mirrors at a fixed angle to each other. For both plane mirrors, the tilt angles can now be determined in each case except for a translational ambiguity. The fixed and known position of the two mirrors can be used, for example, to resolve the translational ambiguities. This idea model can be extended if a curved mirror is modeled as a concatenation of many tilted plane mirrors.

When used in a projection exposure apparatus, in particular an illumination system for an EUV or VUV projection exposure apparatus, the arrangement according to the first embodiment variant of the invention can be provided in the form of an inverted beam path, such that a translatory movement or an offset of the mirrors, in particular perpendicular to the mirror surface (z offset) is automatically compensated.

For example, the method and the device for monitoring or for monitoring a first multiple mirror arrangement can be used, which are arranged in a field level of a lighting system as field facets. These direct the light onto a second multi-mirror arrangement in a pupil plane, the so-called pupil facets or a field-defining element (field-defining element FDE). If now the monitoring device with the pattern instead of the pupil facets and the detection device, for example in the form of the camera, instead of the virtual light source, then corresponding translational movements of the first multiple mirror array (field facets) are automatically compensated. The device for monitoring the mirrors is of course not arranged in the same plane of the beam path as the working light, but tilted about the optical axis, in particular by 90 °, so that no disturbance of the working light beam path takes place. Accordingly, in this embodiment, the pattern to be mirrored may also have a structure that corresponds to the structure of the pupil facets, for example with regard to the arrangement of the light sources.

BRIEF DESCRIPTION OF THE FIGURES

Further advantages, characteristics and features of the present invention will become apparent in the following detailed description of embodiments with reference to the accompanying drawings. The drawings show this in a purely schematic way in

Figure 1 is a perspective view of a structure of an apparatus for monitoring tiltable mirror according to the invention;

Figure 2 is a plan view of a fiction, contemporary arrangement for monitoring tiltable mirrors that can be used in a projection exposure;

FIG. 3 shows a part of a lighting system of a projection exposure apparatus;

Figure 4 is an illustration of a projection exposure system in which a corresponding monitoring system is used;

Figure 5 shows the representation of a pattern for use in the inventive method and the inventive device;

Figure 6 is an illustration of another pattern for use in the method and apparatus of the invention;

FIG. 7 is an illustration of the mirrored pattern of FIG. 6; FIG. 8 shows a detailed representation of the mirrored image from FIG. 7 for the green channel;

FIG. 9 shows a detailed representation of the mirrored image from FIG. 7 for the red channel;

FIG. 10 shows a further example of a sample for use in the method according to the invention and the device according to the invention;

Figure 11 is an illustration of the mirrored pattern of Figure 10; FIG. 12 shows an illustration of a time-varying pattern with four successive partial images for measuring the tilting of a mirror in the x direction;

FIG. 13 is an illustration of a time-varying pattern according to FIG. 12 for measuring the tilt in the y-direction; Figure 14 is a representation of the operation of a mirror tilt on the detected imaging range of the pattern;

FIG. 15 shows a further illustration of a time-varying pattern with a sinusoidal or cosinusoidal pattern in the x direction at three successive points in time;

16 shows an illustration of an arrangement for phase-measuring deflectometry with a time-invariant, two-dimensionally periodic, in particular sinusoidal or cosinusoidal, pattern with a plurality of detection devices (cameras);

17 shows the illustration of the pattern from FIG. 16 with the detection areas of the individual cameras;

FIG. 18 shows an alternative embodiment to the arrangement from FIG. 16 with only one detection device and a plurality of detection regions of the detection device;

FIG. 19 shows an arrangement for producing a pattern on a projection screen using a plurality of transmission masks;

FIG. 20 is an illustration of the control of the individual light sources in the arrangement of FIG. 19 for generating a pattern superimposed on the subpatterns of the individual masks;

Figure 21 is an illustration of the operation of binary masks; FIG. 22 shows an illustration of a lamp arrangement for producing a two-dimensional pattern with 17 lamps for 5 evaluation images in partial image a) and 29 lamps for 8 evaluation images in partial image b);

FIG. 23 shows a representation of a further pattern generation device.

EMBODIMENTS

FIG. 1 shows a first embodiment of an arrangement according to the invention for monitoring tiltable mirrors.

The arrangement comprises a camera 1 which captures an image detail 5 of a pattern 3 which is imaged via one or more mirrors 4 of a so-called mirror array (mirror field). The pattern 3 can be realized in different ways, as will be described in more detail below.

The pattern 3 can be displayed on any screen 2, printed on paper, on a monitor, a surrounding housing or otherwise. It only matters that the area of the pattern 3 spanned in accordance with the coordinate system x _s and y _{s represents} a multiplicity of light sources, which results in at least one image detail 5 being reflected in the direction of the detection device (camera 1) via the mirrors 4 so that the camera 1 can detect the light of the plurality of light sources of the pattern 3.

The camera 1 can be a digital camera according to CCD or CMOS technology, which is capable of taking corresponding pictures at a specific frequency, wherein the picture rate also determines the temporal sampling rate of the measurement.

The image or sensor data ascertained with the camera 1 are transmitted via an appropriate data line 8 to an evaluation unit 7, which determines the orientation of the mirrors 4 of the mirror array by comparing the image determined with the camera 1 on the basis of the knowledge of the pattern 3 6 can perform.

For this purpose, the evaluation unit 7 can perform image recognition by corresponding pattern matching, so that the orientation and orientation of a corresponding mirror 4 can be determined by finding the image detail 5 of the pattern 3 recorded in the camera 1 for the mirror 4.

In the case of several mirrors 4 of a mirror array, besides the pattern recognition, that is to say the determination of the image section 5 of the pattern 3 assigned to a mirror, the corresponding assignment of the imaged pattern to the individual mirror must also take place. This could be done, for example, by the camera 1 only ever detecting only a single mirror 4 and sequentially detecting all the mirrors 4 of the mirror array 6.

However, this could lead to very high measuring times in the case of a large number of mirrors 4 in the mirror array 6, so that a simultaneous detection of several mirrors or all mirrors 4 by the camera 1 is desirable. In this case, the camera optics of the camera 1 be chosen so that a corresponding depth of field can be achieved, in which both the mirrored pattern 3 and the mirror are detected sharp. Thus, a defined area is assigned to each mirror in the image of the camera 1, although different image sections of the mirrored pattern 3 are present depending on the tilt orientation of the corresponding mirror in the assigned image area. For both the sharp image of the mirror 4 and the pattern 3 in the object space of the camera 1, a corresponding optics of the camera 1 with a high depth of field can thus be provided. Accordingly, in this case, the optics of the camera 1 can also be focused on a region between the pattern 3 or the screen 2 and the mirrors 4. If each individual mirror 4 is detected individually by the camera 1, it is possible to focus on the pattern 3 or the screen 2, thus providing a good resolution for the pattern recognition, ie for the comparison between the pattern picked up by the camera 1 and the screen 2 originally produced pattern 3 to be obtained, which is carried out in the evaluation unit 7.

Is in the selected monitoring arrangement, as shown in Figure 1, the tilt angle of a mirror 4, z. B. rotated by rotation about the x and / or y-axis of the xyz coordinate system of the mirror array 6, the coordinate x _{ms changes} ; y _{ms of} the center of the viewed image section 5, wherein a determination of the tilt of the mirror 4 is made possible by a corresponding assignment of the mirrored pattern 3 to the captured image of the camera 1. This variant of the monitoring is advantageous due to the possibility of using any desired pattern, wherein it merely has to be ensured that the pattern does not repeat periodically, so that ambiguities arise, or that these are taken into account in the evaluation.

Focusing the camera 1 on the pattern 3, d. H. a sharp image of the mirror image of the pattern in the image region of the detection device, can also be made if the mirror 4 have a sufficient distance or there is no overlap of the corresponding image areas for each mirror in the camera image.

Another embodiment of an arrangement in which a pattern is also mirrored via mirrors for inclusion in a camera is shown in FIG. In this arrangement, the pattern 30 is formed by a plurality of light sources, e.g. Example, by an LED array (a field of light-emitting diodes) 20 or a corresponding representation on a monitor or the like. The pattern 30 is reflected via a mirror array 60 with individual mirrors 40 in the direction of a camera 10, the camera 10 in the present case being focused on all the mirrors 40 of the mirror array 60, so that each mirror 40 of the mirror array 60 has an image area in it associated with the camera 10. In the case of a multiplicity of micro mirrors, in extreme cases one pixel each of the corresponding sensor of the camera 10 can be associated with a mirror 40 of the mirror array.

By a temporal change of the pattern 30, the orientation of the respective mirror 40 from the light intensities measured by the camera 10 can be determined from various measurements. If, for example, the LED light sources 31 forming the pattern 30 are activated individually or in groups one after the other, so that light radiation is generated at different locations of the pattern 30, which is mirrored into the detection device via a common mirror, then at least three measurements can be made per mirror the absolute orientation of the mirror can be determined. Due to the temporally and spatially variable light intensity of the pattern 30, d. H. with differently connected LED light sources at different measuring times, the orientation of the corresponding mirror 40 can be determined.

For example, the light-emitting diode array 20 may be configured such that a plurality of groups of LEDs are arranged in rows and columns next to each other, each group of LEDs being arranged for imaging through a single mirror in a square, which are switched one after the other.

For this purpose, LEDs can be used which emit light with the same wavelength or a similar wavelength range, and as a camera 10 can serve a black and white camera.

Acceleration of the measurement can be achieved by using light emitting diodes emitting light of different wavelengths. When using different colored LEDs in the light-emitting diode array 20 and using a color camera, the reflected light of differently colored and locally distributed LEDs 31 can be separated from the light emitting diode array 20 of the camera with only one measurement per mirror and according to the different mirror conditions of light with different wavelengths Orientation of the corresponding mirror can be determined. Depending on the structure and arrangement of the mirrors in the mirror array 60 and the light-emitting diodes 31 in the light-emitting diode array 20, an overlap of several light emitting diodes for a given mirror may occur, ie the light of several adjacent groups of light emitting diodes is reflected by a mirror. In order to avoid or reduce the associated requirements in the evaluation, the groups can also be operated separately, for example in the manner of a checkerboard pattern, so that no adjacent groups are operated simultaneously and interfere with each other.

Such a construction of a corresponding monitoring system, as shown in FIG. 2, can in particular be designed such that it represents an inverted beam path of a beam path of an illumination system in a projection exposure apparatus, in particular an EUV illumination system of an EUV projection exposure apparatus.

For example, FIG. 3 shows a portion of an EUV illumination system in which the light of a light source 100 is applied to a mirror assembly 110 in a field plane, i. H. on so-called field facets, on a multi-mirror arrangement 120 in a pupil plane, the so-called pupil facets, is directed. Instead of the discrete pupil facets of the multi-mirror arrangement 120, as may be used in an EUV illumination system, a continuous surface of a so-called Field Defining Element FDE (field-shaping element) may also be provided. The mirror assembly 110 will now be monitored or measured according to the invention so that the mirror assembly 110 corresponds to the mirror assembly 60 of FIG.

As can be seen from FIG. 2, identical or at least similar geometrical relationships are realized by an inverse replica of the beam path of FIG. 3 in the arrangement of FIG. 2, that is to say permutation of the light source and camera or detector, so that when measuring the intensities of the light source reflected light on the mirrors 40, the relative intensity is reproduced, with which the working light of the EUV beam path of Figure 3 is directed to the corresponding part of the pupil facet 120. Thus, any errors can be eliminated by translational offset of the mirror 40 or 140. In this way, the arrangement according to the invention is insensitive to translational displacements of the field facets in the multi-mirror arrangement 110, in particular a corresponding z-offset, that is to say an offset essentially transversely to the mirror surface.

In an EUV lighting system, the LEDs 31 of the LED array 20 may be distributed or grouped according to the arrangement of the pupil facets 120. By increasing the number of light-emitting diodes per group, the measurement accuracy can be increased, but when using light-emitting diodes of the same wavelength by the Nacheinan-betätigen the individual LEDs, the measurement time is extended.

Instead of a grouping of the light-emitting diodes 31 of the light-emitting diode array 20 corresponding to the pupil facets of the multi-mirror arrangement 120, a periodic arrangement, for. B. a square or hexagonal grid can be provided.

FIG. 4 shows how corresponding arrangements according to the invention for monitoring tiltable mirrors, as shown in FIGS. 1 and 2, can be used in a projection exposure apparatus.

The projection exposure apparatus 150 in the embodiment of an EUV projection exposure apparatus comprises a light shaping unit 151, an illumination system 152 and a projection objective 154. The light from the light shaping unit 151, which is shown schematically as a beam path in FIG. 4, is applied to field facets of the illumination system 152, for example Directed multiple mirror array 110, which reflect the light on pupil facets of a multi-mirror assembly 120. At the end of the illumination system 152, a reticle 153 is illuminated and the reflected light is directed onto the substrate 155 in the projection objective 154, so that the structure contained in the reticle 153 is reduced in size on the substrate 155.

2 and 20 schematically show the screen or the light-emitting diode array of a pattern source adjacent to the multi-mirror arrangement 110 to be monitored, the beam path of the monitoring system being perpendicular to the image plane, while the beam path of the working light of the illumination system 152 is substantially in the image plane , So that the two beam paths are tilted by about 90 ° to each other and thus no mutual interference occurs. By an appropriate arrangement of the monitor The ring system outside the beam path of the working light of the illumination system 152 ensures that the monitoring system does not disturb the projection exposure apparatus 150.

While it is sufficient for the second embodiment variant of the arrangement according to FIG. 2 to provide a pattern which provides light intensities starting from locally different light sources, it is important in the arrangement of FIG. 1 and the first embodiment used there correspondingly that a clearly identifiable pattern is given, which can be assigned to the captured by the detection device or camera 1 image in the pattern recognition or image recognition.

For this purpose, various patterns can be used which are distinguishable in terms of time and / or location and with regard to the emitted light. Overall, many types of patterns can be used for the present invention, which can be selected depending on the selected evaluation method and other constraints.

FIG. 5 shows a first embodiment of a pattern in which a square area is designed in such a way that the intensity of the light of a first wavelength, for example light in the red wavelength range, increases in a Cartesian coordinate system in the x-direction, while along the second coordinate axis of the Cartesian coordinate system, ie the y-direction increases the intensity of the light of a second wavelength, so for example light in the green wavelength range. Accordingly, for the x-y area of the pattern a different light source results for each point, which differs in its red or green component. Thus, for example, in one corner of the area there is both a strong red intensity and a strong green intensity, while in the diagonally opposite corner only a low green intensity and a low red intensity are observed. In the other corners of the square surface of the pattern are then correspondingly high proportions of green at low red content or high proportions of red at low green content observed. Overall, there is a clear surface pattern in which no point of the pattern, so no light source, is identical to another point or light source.

If this pattern is now mirrored with the mirror array 6 of the arrangement of FIG. 1 into the camera 1, then the pattern of FIG. 5 stored in the evaluation unit 7 can be used are compared with the image section 5 shown by the respective mirror 4 and a clear assignment of the image section 5, which is mirrored by a corresponding mirror 4 in the image of the camera 1, are made.

From this information, which image detail 5 of the red-green pattern from FIG. 5 has been imaged with which (x, y) coordinates on a particular mirror 4, the orientation and orientation of the corresponding mirror with respect to the tilt can be approximated by an x and y axis can be determined.

The red-green pattern can additionally be configured as an RGB pattern with a blue component, the blue component being uniformly distributed uniformly over the surface in order to be able to determine illumination inhomogeneities with this blue component as the third color component by means of a corresponding normalization and to be able to account for this accordingly.

For example, in the chosen embodiment, it is sufficient to provide a single pixel per mirror in the camera, which pixel is capable of detecting the red-green portions of the light reflected from the mirror. Accordingly, a color camera is used for this purpose. However, instead of a color camera, the use of two or three black-and-white cameras with corresponding color filters may be considered, depending on the number of colors used.

If a plurality of pixels are available for each mirror for detecting the light reflected at the mirror, an averaging can be carried out for the corresponding pixels. In addition, the use of multiple pixels for one mirror can increase the resolution of the tilt measurements and thus improve the association of the image area imaged in the camera with the default pattern. Accordingly, with the illustrated embodiment, monitoring of a plurality of tiltable mirrors in a mirror field, for example in a micromirror array (MMA), can be carried out in a simple manner, which can be used, for example, for illumination adjustment in projection illumination systems for microlithography.

FIG. 6 shows a further embodiment of a pattern which can be used with the arrangement of FIG. This pattern is a periodic representation of light sources with different wavelengths, for example a white light. lenlänge in the red wavelength range and a wavelength in the green wavelength range, wherein the periodicity of the radiation power of the light sources or the intensity of the light radiation in the specific wavelength. For example, as shown in FIG. 6, the intensity of the light radiation over the region predetermined by the xy surface of the pattern can have a sinusoidal profile in each case in the x and y directions. In this case, the sinusoidal curve for the red wavelength range can be arranged in the direction of the x-axis, while the sinusoidal profile of the intensity in the green wavelength range extends along the y-axis. This results in a checkerboard-like pattern with intensity maxima with high light intensity of the green and red light radiation and intensity minima with low red and green light intensity.

Here too, the detection device can accordingly be formed by a color camera, so that the corresponding sensor can determine the color components of the reflected pattern or two black-and-white cameras with corresponding color filters, that is to say a red filter and a green filter in the example chosen, can be used to add the corresponding color components measure up.

If an image detail, which is assigned to a mirror, is viewed in the camera image, the tilt angle around the first tilt axis can be determined in each case in the first color channel by a phase determination. By a phase determination in the second color channel, the second tilt angle can be determined. The background is that the strip or sine pattern in the first color channel of the camera image shifts due to a tilting about a first tilting axis (phase change). By tilting about the second tilt axis, the stripe or sinusoidal pattern shifts in the second color channel. In order to be able to determine the position of the mirror with respect to tilting about the x- and y-axis by means of a phase measurement, at least nine pixels, ie detection points per mirror, are accordingly required. Advantageously, more pixels or detection points per mirror, for example 16 or 25.

The phase measurement can be ambiguous, ie it is not directly detect the absolute mirror position or the Spiegelkipps perform, but only a detection of the relative position or the relative tilt. By tracking the mirror movement (tracking) can nevertheless realize a measuring system, which provides the Spiegelkipp or the mirror position. Prerequisite for the applicability of a tracking is often that the Frame rate of the camera (equal sampling rate of the measurement) is high compared to the time constant of the mirror dynamics. That is, the mirror moves slowly compared to the temporal sampling rate.

FIGS. 7 to 9 show an example of a corresponding image produced by a mirror of the pattern of FIG. 6 in the camera 1. FIG. 7 shows partial images for three juxtaposed mirrors 50, 51, 52, in which, according to FIGS. 8 and 9, the images of the red channel and the green channel are provided in the associated pixel region of the camera. The rectangle shown in FIG. 7 for the mirrors 50, 51, 52 respectively corresponds to the left partial images of FIGS. 8 and 9, wherein in FIGS. 8 and 9 the green and red partial image and the correspondingly depicted sinusoidal pattern respectively are shown.

For the green channel, ie the sine pattern with wavelengths in the green light range, there is a section of slightly more than one period, while for the red channel, ie the light in the wavelength range of the red light, slightly more than two periods of the sine pattern are detected ( see right part of Figs. 8 and 9). If there is a tilting of the corresponding mirror about the x- or y-axis, then the detected sine curve of the green or red light changes and the change in the tilt angle can be detected by changing the phase of the sinusoidal curve. However, as soon as the tilt angle leads to a shift of the sine signal by more than one period, a tracking of the movement of the mirror must be performed (see also below incremental measurement) in order to continue to maintain an absolute localization in the periodic pattern ,

Another embodiment of a pattern is given in FIG. This pattern is a random signal, or a noise pattern, in which it is assumed that the probability that repeating pattern areas are found in the surface area of the x-y area of the pattern is extremely small.

Similar to the preceding patterns of FIGS. 5 and 6, the pattern of FIG. 10 may also be present as an expression or as a representation on a screen, for example a TFT monitor. When displayed in a monitor, a corresponding noise signal can be used for display. Alternatively, a corresponding pattern by a lacquered or structured by other surface treatment surface within the projection exposure system, for example, be given a corresponding housing wall. The assignment of the determined mirror image, which in turn is shown in FIG. 11, for example, for three mirrors 50, 51, 52 arranged next to one another, takes place, for example, via correlative methods which allow the image and pattern to be associated.

Another possibility here is to use gradient-based motion estimations for the measurement when the mirror is already well known (see [Jahne: Digitale Bildverarbeitung, 4th Edition, Chapter 13, Springer Verlag]).

Further alternatives to the use of patterns in the method according to the invention or the arrangement according to the invention are shown in FIGS. 12 and 13. FIGS. 12 and 13 each show four partial images, which have been taken in succession from the pattern. It can be seen here that there is a time-varying pattern in which, for example, a sine wave passes through the pattern surface, both in the x direction and in the y direction for measuring the x tilt angle and the y tilt angle. Contrary to the pattern from FIG. 6, this is therefore not a standing sine wave, but a sine wave passing through in time, so that a periodic change in the radiation of the light sources occurs at all locations of the pattern over time.

By measuring multiple readings for a mirror position, i. H. the recording of at least three, preferably four, eight or more images per mirror position, the phase of the time signal can be determined, which is a measure of the tilt of a mirror in the x- or y-axis. Such a phase shifting method, as used, for example, for the defect detection of painted parts in the automotive industry, can thus also be used for determining the orientation of a mirror and in particular a plurality of mirrors in a mirror array.

In order to achieve a correspondingly high measuring rate for moving mirrors, the rate of the pattern change in the MHz range can be selected, in particular light emitting diode arrays can be used, which can be switched very quickly. Again, the use of light-emitting diodes with two different wavelength ranges of the light can be realized again, wherein by rapidly switching the corresponding lighting diodes of a first wavelength range, for example in red color, the continuous sine wave in the x-direction and switching the LEDs with the second wavelength range, the generation of the continuous sine wave in the y-direction can be generated. In addition, a filter may be provided to realize, for example, an optical low-pass filter, for example in the form of a frosted glass.

The corresponding mirrored pattern is recorded with at least three images per mirror position or Spiegelkipp from a color camera or two black and white cameras with color filter also high frame rate, so that the tilt angle of the mirror can be determined by a corresponding evaluation. Instead of a camera, the direct use of a photodiode array for detection is also conceivable. With such an approach, it is in principle also possible that only one pixel or a detection point, for example a photodiode per mirror, is provided.

FIG. 14 again shows in a schematic representation details of the reflection conditions between the pattern 302, which in the exemplary embodiment shown is provided by a TFT display, the mirror 304 to be measured, whose position is to be determined, and the camera or detection device 301 As clearly shown by the dashed representation of the tilting mirror 304, a different tilting position of the mirror 304, another area of the pattern 302 is detected by the detection device 301 in the form of the camera. This provides the basis for the phase-measuring deflectometry used in one embodiment of the present invention. FIG. 15 shows three snapshots of a temporally and locally changeable pattern, as it is displayed on the TFT display 302 at different times. The TFT display 302, in the embodiment shown in FIG. 15, generates in the x-direction a sine or cosine wave which passes through the image and thus provides a sinusoidal light or gray level distribution along the x-direction. Along the x-direction can thus be determined from the knowledge of the temporal change of the pattern at constant tilt angles, from which location of the TFT display 302 of the detected in the detection device or camera 301 light beam originates. The same can also be carried out for the y-direction in the same way, wherein the orientation determination in the x and y directions can be carried out successively, for example, in order to determine the tilting of the mirror 304 in the x and y directions. For the intensity of the TFT screen 302 in the x direction, the following applies:

If, for example, n = 3 is selected for the number of images, then an image of the light originating from the TFT display 302 and reflected by a mirror can be taken with the images for different phases of the pattern, that is to say images of the pattern as shown in FIG is shown. Since one pixel per mirror suffices for the determination of the mirror tilt, the tilting of a multiplicity of mirrors, for example in a multi-mirror array, can be determined with a camera having a multiplicity of pixels.

For the measured intensities (brightnesses) of the pixels, one can choose the following approach:

For the solution of this linear equation system one thus needs at least three measured intensities. If one chooses n> 3, one obtains a linear compensation task with the general solution.

Instead of the temporally separate determination of the tilting in the x and y directions, the tilt in the x and y directions, ie in independent spatial directions, can follow simultaneously, with either different wavelengths being used for the x and y directions, for example for x Direction green and red for the y direction, or a corresponding superimposed gray gradient through sine or cosine curves in the x and y directions.

For a cosinusoidal intensity curve in both the x and the y direction, the following results:

For measured pixel intensities, one applies analogously to equation (2):

The application of the addition theorems gives:

The same in matrix notation

One thus obtains a system of equations for five unknowns. For this equations system to be uniquely solvable (rank (H) = 5) you need five images (n = 5). For more than five pictures you get again a linear compensation task it applies:

In order to obtain an accurate determination of the angular position of the respective mirrors, the parameters n and m can be selected appropriately. During the parameter n, which indicates the number of images used for the evaluation and thus the

Phase measurement represented in a first direction, must be integer, can for the Parameter m, which represents the phase measurement in a second direction, may also be chosen to be a non-integer value. If a fraction of the value of the parameter n is chosen as the value of the parameter m, for example, if five images (measured values) (n = 5) are given as the value for m = 5/2 or 5/3, then the five images ( Measured values) also in the y-direction five different phases, which are distributed equally.

In order to reduce disturbances of the evaluation, for example by nonlinearities in the corresponding patterns, the parameters n and m can be selected appropriately. In particular, the parameter n, that is to say the number of images to be used for the evaluation (measured value captures), may be in the range between three and twelve images, in particular four to twelve images, preferably six to twelve images. The parameter m is then chosen as a fraction of the parameter n, the denominator again being of the order of magnitude of three to eight, in particular in the range of three to five. Correspondingly, for example, for n = 8, the parameter m would be 8/3 and for n = 12 the parameter m would be 12/5. However, of course, other values are conceivable.

In addition, the accuracy of the phase measuring deflectometry can be increased when a multi-stage method is used. For example, the pattern for the first stage of the method may include a cosine period to roughly determine the positioning and orientation of the mirror. For the second stage, several periods of the cosine signal (pattern) may be superimposed to perform the fine positioning. Due to the superimposition of a plurality of cosine signals, in the case of an ambiguity, that tilt angle or that positioning which comes closest to the coarse positioning from the first stage can be selected. Such a superposed pattern method is also called phase unfolding.

Correspondingly, it is also possible to use a phase-measuring deflectometry with phase unfolding with superimposed images for determining the position of mirrors and, in particular, for determining the tilt angles about an x and ay axis. The phase unfolding process can be implemented in a single step, in addition to a multi-step process with separate images in the different stages for determining fine and coarse positioning, when all of the cosine signals are additively superimposed to produce the pattern. The intensity is thus:

Accordingly, one applies to the measured intensity:

The application of the addition theorems and transformation in matrix notation results in turn in a linear equation system

(15)

In this equations system it follows that the parameters λ, m, n, o and p can be selected for the evaluation or setting of the pattern. The number of images (acquisitions) m can be a minimum of nine in order to solve the system of equations for the nine unknowns. Depending on which accuracy is required for the position determination of the mirror and how exact the intensity distribution of the patterns used is (problem of the non-linearity of the pattern intensities), suitably suitable parameters can be used. For example, the number of images m can be chosen to be 16, the parameters n, o, p again being fractions of the value of the parameter m, for example n = 16/7, o = 16/5 and p = 16/3. For example, for λ, which indicates the number of periods for the fine measurement, a value can be selected equal to 31, whereby it must be ensured that the coarse measurement and fine measurement are adapted to each other, so that incorrect measurements are not assigned to each other.

Instead of a time-varying pattern, it is also possible to use a temporally invariable pattern, in which case several detection devices (cameras) are used for the use of phase-measuring deflectometry. This is shown in the schematic representation of FIG. 16. The pattern 402 points, for example, in x and y Direction a sinusoidal light-dark course (gray shading), which is periodically continued and shown in Figure 17.

FIG. 17 also shows, with the rectangles drawn in, the areas S1 to S5 which the cameras 401a, 401b, 401c, 401d and 401e (detectors) can detect from the pattern 402.

Instead of changing the pattern 402, a different spatial phase of the temporally invariable pattern 402 is detected by changing the position of the cameras 401a to 40e, so that in turn the tilting of the mirror 404 can be determined. The detection ranges S1 to S5 drawn in FIG. 17 show that, given a resolution of one pixel for a mirror, a multiplicity of mirrors in a mirror field can be measured simultaneously.

In addition, this procedure has the advantage that the various detection devices 401a to 40e can take a picture exactly at the same instant when they are connected to one another, for example via a trigger line. This has the advantage that the mirror does not necessarily have to be constant during recording.

A further modification of a corresponding arrangement or the corresponding method is shown in FIG. Instead of a plurality of detection devices 401a to 401e, as in FIG. 16, only one detection device (camera) 501 is provided in this arrangement, which provides different detection regions, wherein different mirrors 505 to 509 place the different regions of the temporally immutable pattern 502 into the different detection regions map the detection device 501. The division of the detection range of the camera 501 can be done in any manner z. In 4, 6, 8, 9, 12 or 16 areas. If only the detection of five areas is required for the phase-measuring deflectometry, then the excess detection range can be used for a determination of the mirror tilt over an absolute gray value or the like, so that mixing or combination methods can be realized, for example, the phase-measuring deflectometry and other methods for determining the tilt of a mirror can be used simultaneously. For example, other methods for coarse determination of mirror tilting can also be used for two-stage methods be used to make the fine determination with the phase-measuring deflectometry or vice versa or make other combinations.

In addition, it is also possible to use the different detection ranges of the camera 501 to apply the two-dimensional, phase-measuring deflectometry twice, for. Once with 5 detection areas (images) for the coarse position determination and on the other with 7 detection areas (images) for the fine positioning. In this case, several cosine periods can be provided in the pattern. Due to the higher resolution of the first two-dimensional, phase-measuring deflectometry, 20 cosine periods in the pattern for the second phase-measuring deflectometry are readily conceivable.

In addition, combined applications of one-dimensional, phase-measuring deflectometry, two-dimensional, phase-measuring deflectometry and absolute value encodings of the background with gray values and / or color values are generally possible.

FIG. 19 shows an embodiment of a pattern generation device in which a pattern is formed on a projection screen 602. For this purpose, a plurality of light sources 630, 631, 633 are provided, which irradiate a corresponding number of masks 620, 621, 623 in the direction of the projection screen 602, so that the patterns of the masks 620, 621, 623 on the projection screen. By means of a control unit 640, it is possible to switch the light sources 630, 631, 633 in a targeted manner one after the other and / or to change their intensity continuously so that the mask pattern on the projection screen 602 and / or its superimposition result in a corresponding pattern as a result of the successive imaging the projection screen 602 leads. Instead of the light sources shown schematically projection devices, such as or slide or beamer or the like can be used. The advantage of such a pattern-generating device lies in the fact that the projection screen can be arranged relatively easily in a space under vacuum, while the light sources with the masks and the control unit can be provided outside the vacuum space. For example, the optics 610, 611, 613 or parts thereof can serve here as parts of the vacuum partition wall, so that such a pattern generation device can be used in particular in projection exposure systems with vacuum areas. Considering in the following the case that four projection channels, ie four light sources are present and the masks with the light sources, so the projection channels each generate a sine pattern with a constant intensity in the y direction, the brightnesses I _{1 of} the projection channels i = 0 .. .3 continuously controlled by the control unit. The projection devices with the numbers 0 to 3 then generate the following image:

Where x, y are the location coordinates, and X is the period of the pattern.

Furthermore, it is assumed that the total intensity I (x, y) on the projection screen results from an addition of the partial intensities Ii I _2, 1 _3, 1 ₄ . If this is not the case with a specific structure (eg non-linear characteristic of the projection screen), this can be achieved by a corresponding transformation of the activation intensities i _1; Correct i _2> i ₃ and i ₄ .

The goal is the generation of a sine pattern with period X with adjustable phase Φ. For this purpose, the light sources are controlled such that i _1; i ₂ i ₃ and i ₄ represent cosine signals with additive constant displaced by 90 ° phases in each case:

The course of the drive signals over the phase Φ to be set is shown in FIG. On the projection screen, the total intensity is obtained by adding the partial intensities:

With the above image signals and characteristics of the drive signals, a total intensity results:

As a result, a cosine signal having an adjustable phase Φ is produced on the projection screen as desired. As described above, the phase can be set continuously (i.e., not quantized) by a corresponding control of the intensities of the light sources. The phase Φ of the pattern can also be made comparatively quickly, so that fast controllable light sources, such. As LEDs, can be used. This allows a high temporal sampling rate in the measurement of Spiegelkippwinkeln achieve.

Instead of continuously setting the phase Φ of the pattern on the projection screen by means of continuously controllable light sources, it is also possible to project permanently defined patterns one after the other and to record one image each time with the camera, ie a mirror image of the respective pattern. For example, four predefined patterns can be projected one after the other, which can be defined as follows:

The use of firmly defined patterns results in a simplified control of the light sources, since the light sources only have to be switched on and off. Of course, a different number of fixed patterns than the exemplified number of four patterns possible.

The continuous adjustment of the brightness of the light sources I ₁ can be done via pulse width modulation (PWM). The pulse width modulation control has the advantage that no digital-to-analog converter are required and the light sources need only be switchable.

Instead of using masks which represent approximately a scaled image of the desired pattern, eg of a sine or cosine pattern, it is also possible to use simple so-called binary masks and at the same time to defocus the imaging optics 610, 611, 613 (as shown in FIG. 19) , so that a corresponding image of the desired pattern takes place on the projection screen 602, as shown for example in FIG. 21. The basic idea here is that the spectra of the rectangular patterns consist of fundamental frequency plus harmonics. Due to the defocusing of the imaging optics, at least approximately all spectral components can be filtered out down to the fundamental frequency. Advantage of the binary masks is that they are technologically relatively easy to produce. Another advantage is that no high demands on the imaging optics or their resolution must be made.

For generating phase-shifting patterns (time-varying patterns), various methods can continue to be used. By way of example, it is possible to generate a phase-shifting, cosine-shaped intensity profile by superposing three fixed patterns, that is to say temporally immutable patterns. The superposition of the individual patterns can take place here in the form of overlaid slide projections or the like. It is also conceivable that the patterns are firmly imaged with different colors on a corresponding background and with special light, such as light from complementary colors, polarized light, etc., are illuminated, so that with the respective color or the light of certain polarization only the that pattern provides an intensity contribution which is associated with the corresponding light color or light polarization. While the superposition of three patterns to produce a phase-shifted cosinusoidal intensity in one direction, that is one-dimensional sufficient, the corresponding method for generating the phase-shifted intensity curve can also be used for two-dimensional pattern, then at least six patterns should be provided, since the phase offset in the corresponding spatial directions, so x and y direction must be different in size.

For the generation of a phase-shifted cosinusoidal intensity profile with three fixed patterns, the intensity profile can be set as follows:

The application of the addition theorems leads to:

From this one obtains for A, B, C the following linear equation system:

With A, B, C> 0 one can show that x> 2y must hold. If we want to use the full dynamic range 0 <I <1 for I, it follows that x = 2/3 and y = 1/3. This gives you:

Another way to create a corresponding pattern is to appropriately switch on and off light sources, such as simple lamps or LEDs (Light Emitting Diodes). This is shown for example in FIG. In the partial image a) of FIG. 22, corresponding illuminants, for example LEDs, are arranged at the locations where the numerals are shown. In sub-picture a), these are 17 LEDs, which are switched one after the other according to the numbering, resulting in five sample pictures. The area inside the dashed inner square represents the effectively used pattern area, while the outer illuminants located in the intermediate area between the inner square and the outer square serve to provide the correct intensity distribution in the inner square caused by the corresponding intensity dispersion external light source is realized. If each lamp provided an intensity distribution of a cosine curve with the period length of the inner square, then an ideal phase-shifted cosine pattern would be given in two dimensions. However, in reality, the lamps have a luminous characteristic similar to a Gaussian bell curve. Around eliminate the inaccuracies introduced thereby, a corresponding choice of the parameters n and m for a two-dimensional, phase-measuring deflectometry with two superimposed periodic patterns, eg a cosine pattern in the x-direction and a cosine pattern in the y-direction (see above). , be made. Accordingly, for example, the value for the parameter n (number of images) could be set to eight, and the value for the parameter m could be set to 8/3. A corresponding arrangement of light sources is shown in FIG. 22 in the partial image b). The numbers indicate again the position of the lamps and the corresponding turning on the lamps to produce the various patterns, so the digit 0, the position of the bulb 0, which is turned on for the pattern 0, the numeral 1, the position for the bulbs, the Pattern 1 are turned on, etc.

The light sources in the form of lamps, LEDs or so-called Gaussian spots can also be multiplied, for example by mirror assemblies, optical fibers or specially ground lens arrays in order to reduce the number of lamps or LEDs or the like.

In principle, one could get along with n lamps, that is to say as many lamps or Gaussian spots as the number of required pictures (detections) (see inner square area in FIG. 22). For the measurement with one period we recommend 4 * n-3 bulbs or spots. For x periods corresponding to n * (x + l) ² -3 bulbs or spots.

Another possibility for producing a pattern and in particular a temporally and / or locally variable, that is moving pattern, is to illuminate a corresponding mask or a perforated plate with different light sources, so that a corresponding pattern is produced on a diffusing screen. This is shown, for example, in FIG. 23 in which three light sources, which can be switched individually, illuminate a perforated plate from three different positions, so that correspondingly different intensity maxima are produced on the diffusing screen, resulting in a shifting cosine profile. While only the generation is shown in one dimension in FIG. 23, it goes without saying that corresponding light sources perpendicular to the image plane can also be provided so that a two-dimensional pattern can be generated. In the perforated plate corresponding color filters can be provided in the various holes of the perforated plate, so that with the help of color cameras, a corresponding evaluation can be made.

In the pattern generation and / or the position and orientation determination, the various methods presented can be combined with one another in order, for example, to enable different accuracies of the positioning determination and then to combine these together. For example, the coarse determination of the positioning could be carried out via a color code, while the fine determination of the positioning takes place via two-dimensional lamp arrangements, so-called Gaussian spots.

In addition, it is possible to use the principle of optical incremental sensors for determining the mirror positioning. The optical incremental sensors, whether they pursue an interferential measuring principle or an imaging principle, have in common that the movement of a scale to a scanning element two signals offset by 90 degrees, namely a cosine and a sine wave, so on the basis of the Measurement determined signal variation, the position change and the position direction is made possible by comparing the signals offset by 90 degrees to each other. For absolute position determination, a marking of a signal period, a so-called index signal, is additionally provided. In other words, by counting the passing periods of the signals and comparing the waveforms of the signals offset by 90 degrees, the positional change can be determined and the absolute position is defined by the index signal.

This principle can generally also be used in determining the position of a mirror, for example by generating a pattern in which the red color component of the pattern has a sine curve, the green color component of the pattern has a cosine curve and a blue index signal is provided is. By means of a color camera, the corresponding pattern, which has been mirrored on the mirrors, can then be detected in order to determine the position by means of a corresponding evaluation of the red, green and blue components.

Since the real detection of the color components leads to deviations from the theoretically expected signal curves, for example due to color distortions of the camera image, compared to term crosstalk of red and green shares, etc., may be required a corresponding correction, which can be preferably carried out according to the Heydemann correction.

The incremental position determination according to the principle of optical incremental sensors can be used not only for the determination of the tilt about an axis of rotation, but also for the determination of the tilt angle about two independent axes of rotation. In this case, two patterns and two cameras should be provided accordingly.

In principle, it is sufficient with this measuring principle that only one camera pixel is evaluated per mirror. This pixel may then contain only light components of this one mirror. However, it is also conceivable that in the incremental measuring method several mirrors are measured with a camera pixel. The following procedure is suitable here, which can also be transferred to the other methods presented for determining the position.

According to a first variant, in each case only one mirror is moved out of the group of mirrors which are assigned to a camera pixel. Since the other mirrors show no change in position, the change detected in the camera pixel, for example, of the red and green components is attributable only to the one mirror, so that its positional change can be determined. For a corresponding Heydemann correction, however, should be tilted by at least one signal period.

The second possibility to measure several mirrors with one camera pixel is that all but one mirror are placed in such a way that they do not contribute to the camera pixel, thus for example reflecting a black background or border area in the camera pixels. Thus, the light intensities detected by the camera or light intensities generally detected by a detection device can only be attributed to the remaining mirror, and this can be exactly determined in its position.

With the arrangements and methods shown, it is thus possible without costly and possibly voluminous optics to realize a monitoring of tiltable mirrors, in particular for a large number of mirrors in a mirror field, such as an MMA. In addition, the measuring channels of the individual mirrors are largely decoupled, ie in most variants of the illustrated measuring methods / arrangements there is no crosstalk between the measuring channels for individual mirrors. The measured value of a mirror is then completely independent of the tilt angles or measured values of other mirrors.

The invention can thus be realized in various embodiments. The following list of preferred but non-limiting embodiments is numbered for simplicity with the features:

An apparatus for monitoring the orientation of at least one mirror (4, 40) with detection means (1, 10) for detecting the light reflected from the mirror, wherein a pattern source (2, 20) is provided having a pattern (3, 30) ) with spatially and temporally or temporally variable light sources (31), which is mirrored by the at least one mirror onto the detection device or that a pattern source (2, 20) is provided, which spatially and / or spatially intersperses a pattern (3, 30). or temporally variable light sources (31) which is mirrored onto the detection device by the at least one mirror, wherein the detection device is designed such that the mirror or mirrors are imaged in a defined manner on the detection device and exactly one detection region of the detection device is associated with each mirror , or that a pattern source (2, 20) is provided, which has a pattern (3, 30) with spatially and / or temporally variable light intensity 31), which is mirrored by the at least one mirror onto the detection device, wherein the detection device is designed such that it detects changes in the detected pattern over time.

2. Device according to feature 1, wherein the device comprises an evaluation unit (7) which determines an absolute or relative position of the mirror or mirrors from the pattern to be mirrored and the detected, reflected light.

3. Device according to one of the preceding features, wherein the detection means (1,10) comprises at least one element of the group, the Black and white cameras, black and white cameras with color filters, color cameras, charge coupled device (CCD) sensors, CMOS (complementary metal oxide semiconductor) sensors and photodiodes.

4. Device according to one of the preceding features, wherein the detection device (1,10) comprises at least one optics, which is prepared so that can be focused on the pattern to be mirrored and / or on the mirror or mirrors and / or an area between them ,

5. The apparatus of claim 4, wherein the optics of the detection device (1,10) has a sufficiently high depth of field for imaging mirror and specular to be mirrored.

6. Device according to one of the preceding features, wherein the detection means (1,10) comprises a plurality of independent pixels for locally separated light detection, wherein each mirror is associated with at least one pixel.

The device of claim 6, wherein each mirror (4, 40) is associated with at least 9 pixels.

The device of claim 6, wherein each mirror (4, 40) is associated with at least 16 pixels.

The apparatus of claim 6, wherein each mirror is associated with at least 25 pixels.

10. Device according to one of the preceding features, wherein

Detection device (1,10) and pattern source (2,20) are so arranged relative to the one or more mirrors (4,40) that they do not interfere with one or more working beam paths of the mirror or mirrors. 11. Device according to one of the preceding features, wherein at least two detection devices are arranged.

12. Device according to one of the preceding features, wherein a plurality of detection means are arranged side by side so that with respect to a mirror different reflection angle with respect to a fixed-time, locally periodic and / or sinusoidal or cosinus-shaped pattern are given, so that different areas of the Pattern in the various recording devices.

13. The device according to claim 12, wherein instead of a plurality of detection devices only one detection device having a plurality of detection regions is provided, which correspond to different regions of a pattern reflected by a mirror.

14. Device according to one of the preceding features, wherein the detection device is designed so that over a period of time, continuously or at intervals, the pattern reflected by a mirror can be detected.

15. Device according to one of the preceding features, wherein the pattern source (2,20) comprises at least one element of the group comprising a monitor, a TFT screen, a light field with and without filter, a light-emitting diode array, a structured surface, a painted surface , any textured or textured surface and a pattern image with and without illumination.

16. Device according to one of the preceding features, wherein the pattern source (20) is prepared such that a pattern can be generated or present in at least one direction and / or in independent spatial directions (x, y direction) at least one periodic and / or sine or cosine pattern and / or multiple overlaid periodic and / or sine or cosine patterns

17. Device according to one of the preceding features, wherein the pattern source (2, 20) comprises light sources of different wavelengths of light, the light of particular wavelengths being associated with particular positions in the pattern and / or varying in intensity over the pattern.

18. Device according to one of the preceding features, wherein the pattern represents an area in which the intensity of the light of a first wavelength is continuously or stepwise changed in one direction and in another direction, the intensity of the light of a second wavelength is also changed.

19. The apparatus of claim 18, wherein the intensity of the light of a wavelength in one direction continuously or gradually increases or decreases or has a periodic change or a sine wave.

20. Device according to one of the preceding features, wherein the pattern source (20) can generate temporally variable patterns (30).

21. Device according to one of the preceding features, wherein the pattern source (20) is prepared such that the pattern (30) can be varied in time such that for each location of the pattern, a periodic change in the light intensity is given.

22. Device according to one of the preceding features, wherein the pattern source (20) is prepared such that the phase of a periodic pattern and / or a sine or cosine pattern can be varied over time.

23. Device according to one of the preceding features, wherein the pattern source (20) is prepared such that the pattern in at least one direction and / or in independent spatial directions (x, y direction) temporally successively or simultaneously and / or with light of different Wavelength can have time-variable periodic and / or sine or cosine patterns. 24. Device according to one of the features 20 to 23, wherein the pattern source (20) is prepared such that the temporally variable pattern is generated by temporally successive or temporally variable superimposition of different, temporally immutable pattern.

25. Device according to one of the features 1 to 19, wherein the pattern source (20) is prepared such that the pattern is fixed in time.

26. Device according to one of the preceding features, wherein the pattern represents an area in which a randomly generated or any noise pattern is present.

27. An apparatus according to any one of the preceding features, wherein the pattern of the pattern source comprises a periodic grid or discrete areas with one or more light sources.

28. Device according to one of the preceding features, wherein the pattern source comprises at least one light source, preferably a plurality of light sources whose radiation intensity is continuously or stepwise and / or periodically, in particular modulated by a pulse width modulated control.

29. Device according to one of the preceding features, wherein the pattern source comprises a plurality of light sources, which are switchable in groups.

30. Device according to one of the preceding features, wherein the pattern source comprises at least one mask which has a pattern and which is irradiated by at least one light source in the transmission mode or in the reflection mode.

31. Device according to one of the preceding features, wherein the pattern source comprises a plurality of light sources which comprise a grid or a mask of illuminate different positions simultaneously, in groups and / or in succession or wherein each light source is associated with a mask for generating a pattern, wherein the patterns of multiple masks are superimposed and / or temporally successively generated.

The apparatus of claim 30 or 31, wherein the pattern source comprises at least one mask from the group comprising binary masks, grayscale masks, and color masks.

33. Device according to one of the preceding features, wherein the pattern source comprises at least one luminescent screen on which the pattern can be generated.

34. Device according to one of the preceding features, wherein the pattern source comprises at least one optic with which at least one pattern can be imaged.

35. A method for position detection of at least one mirror (4,40), wherein light reflected from the mirror is detected by a detection device (1,10), wherein a pattern source (2,20) is arranged so that spatially and temporally or time-varying light of the pattern (3, 30) of the pattern source is mirrored onto the detector by the at least one mirror or a pattern source (2, 20) is arranged so that a pattern (3, 30) with spatially and / or temporally variable Light sources (31) is mirrored by the at least one mirror onto the detection device, wherein the detection device is operated in such a way that the mirror or mirrors are imaged in a defined manner onto the detection device and each mirror is assigned exactly one detection range of the detection device or if a pattern source (2, 20) is arranged so that the spatially and / or temporally varying light of the pattern (3,30) of the pattern source by more mirror is mirrored on the detection device, wherein a plurality of mirrors are associated with a detection range of the detection device, but only for a mirror alone the position is determined. 36. The method of claim 35, wherein the detection device (1, 10) is arranged and / or comprises optics, so that the detection device is focused on the mirror (s) and / or on the provided pattern or on an area therebetween, and or the mirror (s), and / or the pattern provided, or an area therebetween, are imaged onto the detector.

37. The method of claim 35, wherein the orientation and / or position of the mirror is determined by comparing the pattern provided by the pattern source with the light detected by the detection device.

38. The method according to claim 37, wherein the comparison is carried out by an evaluation of the detected light intensities of light reflected at a mirror from locally differently arranged light sources.

39. The method according to any one of features 35 to 38, wherein for each mirror, the reflected light of at least three distinguishable for the detection means light sources of the pattern is evaluated.

40. Method according to one of features 35 to 39, wherein at least three light intensities reflected at a mirror are processed, wherein the measurements take place successively at the same wavelength of light or simultaneously for different wavelengths of light.

41. The method according to one of the features 37 to 40, wherein the comparison is effected by an evaluation of the detected light intensities of light reflected by a mirror of at least one time-varying light source.

42. The method of claim 41, wherein at least two temporally successive measurements are performed. 43. The method according to one of the features 35 to 42, wherein a phase shift method for determining the position of the at least one mirror is used and / or that in the evaluation according to the principle of phase-measuring deflectometry multiple detections of a pattern reflected by a mirror are used, wherein a minimum number of Detections (s) is given, which is preferably increased to a multiple with a multiplier less than 10, preferably less than 3.

44. The method of claim 43, wherein in a two-dimensional phase-measuring deflectometry for the evaluation, a parameter pair (n, m) can be selected, which with a first parameter (n) represents the number of acquisitions and corresponding to the different phases in a spatial direction and with a second parameter (m) representing the different phases in a different spatial direction, the second parameter (m) being a fraction of the first parameter (n) with the first parameter (n) in the numerator and an integer denominator.

45. The method according to one of the features 43 to 44, wherein in the measurement according to the principle of phase-measuring deflectometry, the principle of phase development is applied.

46. The method of any one of features 37 to 45, wherein the comparison is made by pattern matching between the pattern of the pattern source and the pattern imaged on the detector by a mirror.

47. The method according to claim 46, wherein correlative methods are used for the pattern comparison.

48. The method of claim 46 or 47, wherein in the vicinity of the target value of the position of the mirror and / or with approximate knowledge of the position of the mirror, a gradient-based motion estimation is used for the measurement. 49. Method according to one of the features 35 to 48, whereby optical incremental methods are used for determining the position of a mirror, in which position changes of the pattern imaged by the mirror are detected in the detection device by the change in position of the mirror.

50. The method according to one of the features 35 to 49, wherein in the position determination of a mirror of a mirror group, the other mirrors of the mirror group are set so that they can not reflect light on the detection device or are held stationary during a change in position of the mirror to be determined.

51. The method according to one of the features 35 to 50, wherein the pattern is periodically and / or sinusoidally or cosinus-shaped temporally varied, wherein the position of the mirror is determined by temporally successive detections of the mirrored pattern.

52. Method according to one of features 35 to 51, wherein the pattern is arranged in at least one direction and / or in independent spatial directions (x, y direction) successively or simultaneously and / or with light of different wavelengths corresponding to periodic and / or sinusoidal or cosine pattern is varied over time.

53. The method according to any one of features 35 to 52, wherein a plurality of detection means or a detection means having a plurality of detection areas detect a temporally invariable periodic pattern and / or a sine or cosine pattern side by side with different reflection angles to a mirror element, so that a phase-measuring deflectometry can be performed ,

54. The method of any one of features 35 to 53, wherein one or more to generate a pattern with one or more light sources Masks or gratings are sequentially illuminated and / or irradiated for mutual overlay.

55. The method of claim 54, wherein the radiation intensity of the light sources is changed continuously or stepwise and / or periodically, in particular sinusoidal or cosinusoidal, preferably pulse width modulated.

56. The method of claim 54 or 55, wherein in the pattern generation, the irradiated or illuminated mask is imaged by optics defocused.

57. The method according to any one of features 35 to 56, wherein the light sources of the pattern are switched in groups, wherein adjacent groups are not switched simultaneously.

58. The method according to any one of features 35 to 57, wherein the light sources of the pattern are switched periodically.

59. The method according to any one of features 35 to 58, wherein an at least two-stage method is used, in which after a rough determination of the position, a fine determination of the position takes place, wherein the different stages, the same or different methods for determining the position are used.

60. Method according to one of the features 35 to 59, wherein the shape of the mirror is taken into account for the comparison of the pattern with the light detected by the detection device.

61. The method according to one of the features 35 to 60, wherein in addition to the position detection is carried out a regulation of the position of the mirror or. 62. The method according to one of the features 35 to 61, wherein a device according to one of the features 1 to 34 is used.

63. Projection exposure apparatus for microlithography with at least one device according to one of the features 1 to 34.

64. The projection exposure apparatus according to claim 63, wherein a first multiple-mirror arrangement (110) is arranged in a lighting system (152) in a field plane, which directs the working light onto a field-defining element (FDE) or a second multiple-mirror arrangement (120) in a pupil plane wherein for monitoring the first multi-mirror arrangement, a device according to one of the features 1 to 19 is arranged such that detection means and pattern source corresponding to an inverted beam path of the working light from virtual light source to the pupil plane of the field-defining element or the second multi-mirror array are arranged.

A projection exposure apparatus according to claim 63 or 64, wherein the pattern of the pattern source in the arrangement of the light sources corresponds to the structure of the second multi-mirror array.

66. Projection exposure system according to one of the features 63 to 65, wherein at least part of an optical system of the pattern source and / or an optical system of the detection device serves as a component of a gas-tight separation, in particular a vacuum partition wall.

Although the present invention has been described in detail with reference to the described embodiments, it will be understood by those skilled in the art that the invention is not limited to these embodiments, but rather variations in various combinations of individual inventive features as well as omission of individual inventive features are possible without the The scope of the appended claims leave. In particular, the present invention claims the combination of all presented individual features.

Claims

1. Device for monitoring the orientation of a plurality of mirrors (4, 40) of a mirror arrangement in a microlithographic projection exposure apparatus with a pattern source (2, 20), and at least one detection device (1, 10), characterized in that a pattern source (2, 20) provides a pattern (3, 30) with spatially and / or temporally variable light sources (31), which is mirrored by one or more of the mirror elements onto the detection device, wherein

- One or more of the detection means are adapted to detect changes in the detected pattern as a function of the time and / or the location, and the orientation of one or more mirrors is determined by comparison with a further pattern, or

- Wherein the detection means is formed so that the mirror or mirrors are mapped to the detection means and each mirror is associated with exactly one detection range of the detection device.

2. Apparatus according to claim 1, characterized in that the device comprises an evaluation unit (7) which determines an absolute or relative position of the mirror or mirrors from the pattern to be mirrored and the detected, reflected light.

3. Device according to one of the preceding claims, characterized in that the detection means (1,10) comprises at least one element of the group, the black and white cameras, black and white cameras with color filters, color cameras, CCD (charge coupled device ( charge-coupled device)) - sensors, CMOS (complementary metal oxide semiconductor (complementary metal oxide semiconductor)) - having sensors and photodiodes.

4. Device according to one of the preceding claims, characterized in that the detection device (1,10) comprises at least one optics, which is prepared, that it is possible to focus on the pattern to be mirrored and / or on the mirror or mirrors and / or an area between them.

5. The device according to claim 4, characterized in that the optics of the detection device (1,10) has a sufficiently high depth of field for imaging of mirrors and mirrored pattern.

A device according to any one of the preceding claims, characterized in that the detection means (1, 10) comprise a plurality of independent pixels for spatially separated light detection, each mirror being associated with at least a number of pixels selected from the group comprising one pixel , at least 9 pixels, at least 16 pixels and at least 25 pixels.

7. Device according to one of the preceding claims, characterized in that

Detection device (1,10) and pattern source (2,20) are so arranged relative to the one or more mirrors (4,40) that they do not interfere with one or more working beam paths of the mirror or mirrors.

8. Device according to one of the preceding claims, characterized in that at least two detection devices are arranged.

9. Device according to one of the preceding claims, characterized in that a plurality of detection means are arranged side by side, that with respect to a mirror different reflection angle with respect to a temporally fixed, locally periodic and / or sinusoidal or cosinus-shaped pattern are given, so that different areas of the pattern are detected in the different detection devices.

10. The device according to claim 9, characterized in that instead of a plurality of detection means only one detection means is provided with a plurality of detection areas corresponding to different areas of a pattern reflected on a mirror.

11. Device according to one of the preceding claims, characterized in that the detection device is designed so that over a period of time continuously or at intervals the pattern reflected by a mirror can be detected.

12. Device according to one of the preceding claims, characterized in that the pattern source (2,20) comprises at least one element of the group comprising a monitor, a TFT screen, a light field with and without filter, a light-emitting diode array, a structured surface, a painted surface, any textured or textured surface, and a pattern image with and without illumination.

13. Device according to one of the preceding claims, characterized in that the pattern source (20) is prepared such that a pattern can be generated or is present in at least one direction and / or in independent spatial directions (x, y direction) at least has a periodic and / or sine or cosine pattern and / or a plurality of superimposed periodic and / or sine or cosine patterns and / or time-sequentially or simultaneously and / or with light of different wavelengths temporally variable periodic and / or sinusoidal or Cosine pattern

14. Device according to one of the preceding claims, characterized in that the pattern source (2,20) comprises light sources with light of different wavelengths, wherein the light of certain wavelengths is assigned to certain positions in the pattern and / or varies in intensity over the pattern.

15. Device according to one of the preceding claims, characterized in that the pattern represents an area in which the intensity of the light of a first wavelength is changed continuously or stepwise in one direction and also changes the intensity of the light of a second wavelength in another direction becomes.

16. The apparatus according to claim 15, characterized in that the intensity of the light of a wavelength in one direction continuously or gradually increases or decreases or has a periodic change or a sine wave.

17. Device according to one of the preceding claims, characterized in that the pattern source (20) can generate temporally variable pattern (30).

18. Device according to one of the preceding claims, characterized in that the pattern source (20) is prepared such that the pattern (30) can be varied in time so that a periodic change in the light intensity is given for each location of the pattern.

19. Device according to one of the preceding claims, characterized in that the pattern source (20) is prepared such that the phase of a periodic pattern and / or a sine or cosine pattern can be varied over time.

20. Device according to one of the preceding claims, characterized in that the pattern source (20) is prepared such that temporally variable pattern is generated by temporally successive or temporally variable superposition of different, temporally immutable pattern.

21. Device according to one of the preceding claims, characterized in that the pattern source (20) is prepared such that the pattern is fixed in time.

22. Device according to one of the preceding claims, characterized in that the pattern represents an area in which a randomly generated or any noise pattern is present.

23. Device according to one of the preceding claims, characterized in that the pattern of the pattern source comprises a periodic grating or discrete areas with one or more light sources.

24. Device according to one of the preceding claims, characterized in that the pattern source at least one light source, preferably several light sources um- summarizes whose radiation intensity is continuously or stepwise and / or periodically, in particular modulated by a pulse width modulated control.

25. Device according to one of the preceding claims, characterized in that the pattern source comprises a plurality of light sources, which are switchable in groups.

26. Device according to one of the preceding claims, characterized in that the pattern source comprises at least one mask which has a pattern and which is irradiated by at least one light source in the transmission mode or in the reflection mode.

27. Device according to one of the preceding claims, characterized in that the pattern source comprises a plurality of light sources which illuminate a grid or mask from different positions simultaneously, in groups and / or successively or wherein each light source is associated with a mask for generating a pattern, wherein the patterns of multiple masks can be overlaid and / or generated in succession.

28. Device according to one of the preceding claims, characterized in that the pattern source comprises at least one mask from the group comprising binary masks, grayscale masks and color masks.

29. Device according to one of the preceding claims, characterized in that the pattern source comprises at least one luminescent screen, on which the pattern can be generated.

30. Device according to one of the preceding claims, characterized in that the pattern source comprises at least one optical system, with which at least one pattern can be imaged.