WO2001045390A1

WO2001045390A1 - Camera with multiple tapered fiber bundles coupled to multiple ccd arrays

Info

Publication number: WO2001045390A1
Application number: PCT/US2000/032455
Authority: WO
Inventors: Sigurd Ziegler; Hermann J. Esser
Original assignee: Video Scope International, Ltd.
Priority date: 1999-12-17
Filing date: 2000-12-14
Publication date: 2001-06-21
Also published as: AU3073701A

Abstract

A camera with multiple tapered bundles (110) coupled to multiple CCD arrays (130) is presented. Each tapered bundle (110) is optically coupled to a lens assembly (115) and the lens assembly (115) together with the individual optical bundles (110) couples optical radiation for imaging on a respective CCD array (130). Each tapered bundle (110) consists of a bundle of optical fibers, the cross-section of which narrows to efficiently couple to the CCD array (130). The lens assemblies (115) and tapered bundles (110) can be arranged so that their individual fields-of-view combine to form a composite field-of-view. In a preferred embodiment, the composite field-of-view is made to be a continuous field-of-view in excess of 180 degrees to provide an aerial reconnaissance and tactical mapping camera that provides real-time digital data.

Description

CAMERA WITH MULTIPLE TAPERED FIBER BUNDLES COUPLED TO

MULTIPLE CCD ARRAYS

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to a digital camera svstem, and more parucularly, a digital camera with multiple tapered bundles coupled to multiple CCD arrays tor wide-angle photography instantaneously without loss of detail, distorπon, and without moving parts.

2. Background of the Related Art

Scanning cameras have traditionally been used for gathering informauon or searching for objects in a scanned region. However, many conventional cameras

narrow coverage that limits the range tor observing an area unless the camera is rotated to scan a larger area. Additionally, scanning from a moving platform distorts the captured image.

Figure 1 shows a related art pnsm area lens arrangement for providing greater than

180° of lateral (horizon-to-horizon) coverage. Figure 1 shows a lens arrangement 10 that includes five reflecting pnsms 30 and five biconvex (converging) lenses 20 for reflecting and fixating an image located at one ot the directional regions measured from the vertical plane at 0°. With this prism and lens arrangement, images can be observed at different angles, and combined to form a single frame covering an angular field-of-view of over 180° across track.

Figure 2 illustrates an example of the lateral coverage provided by the prism and lens assembly as shown in Figure 1. In Figure 2, an airplane 50 is located at an altitude (Η) above ground level. When a related art camera 80, located at the underside of the airplane 50, and the lens arrangement 10 shown in Figure 1 records a snapshot, images covering an angular field-of-view of over 180° across-track can be recorded on film. The images cover ground regions 60, 62, 64, 66 and 68. One example of such a related camera 80 is a Zeiss KS- 153 Aerial Camera Svstem.

Documentauon of the Zeiss KS- 153 aeπal camera system is incorporated bv reference in its entirety. The KS- 153 aerial camera system uses the lens arrav of Figure 1 to cover a large 9.5 inch wide format of aeπal film showing 182.7° instantaneous field-of-view with five 60mm lenses and a penta-pπsm array. The lateral coverage is displayed bv combining hve across- track images per frame such that each frame covers an angular field-of-view of 182.7° across track and 47.4° along track. The Zeiss KS- 153 camera uses lens arravs that expose five laterally ad)acent images on a single 9.5 inch wide film. Accordingly, hoπzon-to-hoπzon photographs can be taken bv the related art camera 80 on the airplane 50.

Those images, however, cannot be transmitted in situ to external deλices for viewing, such as a satellite 70 or a remote station 72. Instead, the film itself must be developed before it can be viewed. Tins often necessitates transporting the film to another location. Also, digital analysis including object identification cannot be performed direcdv on film images until the film is developed, and image information on the film therefore cannot be immediately used for purposes of flight control.

Accordingly, a different system and method is needed for recording and transmitting clear and undistorted images covering a large field of video, such as over 180° of coverage, as required to record a scene from an airplane from hoπzon-to-hoπzon.

The above references are incorporated bv reference herein where appropπate for appropπate teachings of additional or alternative details, features and/or technical background.

SUMMARY OF THE INVENTION

The digital camera system according to the present invention uses a tused focal plane of fiber optic tapers that separate the focal plane to match the size of standard CCDs and divide the lateral area into usable bandwidth outputs by using commercially available digital cameras. The design of the digital camera, with the image dividing fiber optic taper array, enables digital imaging with prisms and lens arravs for coveπng the large 9 5 inch wide tormat ot aerial film. It is an object of this invention to provide a camera that provides wide- angle lateral coverage with photogrammetric (mapping quality) accuracy.

An embodiment of the invention uses a penta-pπsm lens arrav for matching imaging of the five lenses to five progressively scanned camera channels for providing outputs of five 1024x1024 digitally processed image channels.

In another embodiment, the fiber optic tapers include millions of glass clad fibers fused into a precisely coordinated assembly drawn into a block or "boule," which is a fiber optic magrufier/minifier. These boules are uniformly tapered to create images free of distortion. The focal plane used with film in the related film camera can be used as the focal plane of a fused fiber optic array with digital output. Imaging is directed from the large film area through the minifying tapers to five progressive scanning frame transfer CCD imagers. Exposure control can be on the CCD and asynchronous mode frame capture can occur within 10 microseconds down to a few nano seconds, allowing for their use as real-πme cameras.

Transmission of an image through the fiber optic tapers is captured in the visible and near-IR spectrum, matching the quantum efficiency of the CCDs The fiber design includes strav light absorbing elements such as extramural absorption, and an optical insulauon, such as cladding, is positioned between the fibers to provide optical image contrast at maximum resolution and transmissivitv.

In another embodiment, the fiber optic taper is coupled to image intensifiers. In another embodiment, an intensifier is bypassed and the small end of the taper is matched to fit the (YD format. In these embodiments, the taper is a minifier.

Software controls the imaging and provides seamless stitching ot the images to provide a continuous film appearance Still imaging and digital stereo display software provide the imaging. For example, the software enables completely adjustable exposure timing, and provides control of the overlap of images. One such overlap is 56°, which is the standard for film image capture in stereo for aeπal mapping and reconnaissance.

The fiber optic taper design operates as an opπcal adapter for fitting a given image size to a size of a CCD array. The fiber optic taper fits the given image size to the CCD array instantaneously, and without distortion, without loss of detail, and without moving parts, such as scanners. This approach provides the benefit of allowing distortion-free aerial photography that is usable in stereo tormat tor photogrammetricallv correct imaging Accordingly, this approach also overcomes at least the problem of conventional scanning cameras having double-barrel distortion that makes the cameras unusable for accurate geo- posiuoning of objects, and useless for mapping. Those conventional scanning cameras were developed to assess inflicted damage using landmarks rather than geo-posiπoning

The digital camera using the fiber optic taper array does not have moving parts and is lighter and smaller than film cameras or comparable scanning devices. The taper array of multiple outputs from a wide-angle view format usable for photogrammetric tasks, such as geo-posiπomng and mapping, are features of the embodiments of this invention Additional advantages, objects, and features of the invention will be set foπh in part in the descπpπon which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or it mav be learned from practice of the invention. The objects and advantages of the invention mav be realized and attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be descπbed in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein:

Figure 1 illustrates a related art pπsm and lens arrangement for providing greater than 180° ot lateral field-of-view coverage;

Figure 2 illustrates an example of the lateral coverage provided bv the related art pπsm and lens assembly shown in Figure 1 ; Figure 3A is a drawing which illustrates a digital camera svstem according to a preferred embodiment of the present invention;

Figure 3B is a drawing which shows a more detailed view ot the fiber opuc taper assemblv of Figure 3A;

Figure 3C is a drawing which shows a side view and a cross-sectional view of a boule or bundle according to an embodiment of the invention;

Figure 3D is a drawing which shows a side view ot a preferred embodiment of the fiber opuc taper assembly group which captures a seamless image;

Figure 3E is a drawing which shows a top view of an arrav series tor use with the fiber opuc taper assembly group of Figure 3D to produce the seamless image; Figure 3F is a drawing which shows the fiber opuc taper assembly with four narrow- fields of view;

Figure 4 is a drawing which illustrates another preferred embodiment of the digital camera system as used with a svstem;

Figure 5 is a drawing which illustrates another preferred embodiment of the digital camera system positioned on a helicopter;

Figure 6 is a drawing which illustrates another preferred embodiment of the digital camera system positioned on an automobile for gatheπng unobstructed images of the side and rear regions of the vehicle;

Figure 7 is a drawing which shows a digital camera svstem according to another preferred embodiment of the invention;

Figures 8A-8D are drawings which provide examples ot composite fields of view, Figure A is a drawing which shows an embodiment of a digital camera with fields-of- view which can be controllablv vaπed in direction using field-of-view (FOλ⁷) controller with motors coupled to fiber optic taper assemblies, respectively; and

Figure 9B is a drawing which shows a digital camera svstem with independendy controllable individual fields-of-view according to another preferred embodiment of the invention

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The digital camera system according to one embodiment of the invention obtains geometrically correct high quality imagery with over 180° of lateral coverage in a single exposure without moving parts or distortion The fiber optic focal plane of the digital camera system has the same dimensions and lateral coverage as the related art aerial camera system ot Figures 1 and 2 The design ot the fiber optic tocal plane allows for transformation of the optical image to match numerous high resolution digital camera arrays. Accordingly, the digital camera svstem of the preferred embodiments is flexible enough to accommodate different CCD format sizes with increased performance. Operational use of the digital camera system is advantageous because it provides transmittable real-time digital images without the delays and inefficiencies of film development

Figure 3 A illustrates a digital camera svstem 100 according to a preferred embodiment of the present invention. In general, as shown in Figure 3A, the digital camera svstem 100 includes a fiber optic taper assembh group 1 3 with five fiber opuc taper assemblies 102

Each of the fiber opuc taper assemblies 1 2 includes an auto-gateable image intensifier 120 attached to the output end 104 (see also output surface 157 of Figure 3B) of the fiber optic boules 1 10. The image intensifiers 120 are auto-gated for exposure control of incoming light bv an exposure control circuit 160 and an attached power supply 162. The exposure control circuit 160 can further include an automatic saturation dπver circuit to prevent saturation

To achieve lateral coverage and sufficient resolution according to one preferred embodiment of the invention, a respective 1024x1024 pixel 10-bit digital CCD arrav 130 is coupled to each image intensifier 120. It should be understood that alternative CCDs could be used.

Figure 3B shows a more detailed view of the fiber optic taper assemblv 102 of Figure 3A. The lens assemblv 115 can be any type of single lens or lenses, mirrors, IR lenses, filters, telescopes or the like grouped in a manner such that optical radiation 141 is collected bv lens assembly 1 15 and focused to a focal plane 143 An input surface 151 of boule 110 is aligned with focal plane 143 of lens assemblv 1 15. The distance d is determined bv the back focal distance of lens assembly 1 15 set at infinity or the hvper focal distance for aerial work. It should be understood that the focal length F of lens assembly 1 15 determines the location of the focal plane where the image is produced. Boule 1 10 need not be parallel to or equidistant from lens assemblv 1 15. For example, if lens assemblv 1 15 were constructed so as to produce an image at a focal plane 143', an input surface 151 would be aligned with focal plane 143'. Regardless of the relative distance d between lens assembly 1 15 and boule 110, in a preferred embodiment, it is desirable that optical power from optical radiation 141 that is received bv lens assembly 1 15 is efficienth coupled into individual fibers comprising boule

1 10. Accordingly, the angle of input of optical radiation at input surface 151 should be made sufficiently low so that optical radiation is collected by lens assemblv 1 15 is cfficiendv coupled to boule 1 10

Continuing to refer to Figure 3B, boule 1 10 optically compresses an image at input surface 151 and outputs the same at output surface 157. Output surface 157 of boule 110 is, in turn, optically coupled to CCD arrav 130. Auto-gateable image intensifier 120 can be placed between output surface 157 and CCD array 130 to provide the gating capabilities discussed above. A relative position between lens assembly 1 15 and boule 1 10 is calibrated for optimum resolution and can be secured with attachment frame or mechanism 163. Attachment frame or mechanism 163 should be of Kovar, or similar material, and preferably of the same thermal coefficient as the lens assembh . \ttachment frame or mechanism 16^~ can be used to affix the position between output surface 157 ot optical boule 1 10 and CCD arrav 130. In addition, if auto-gateable image intensifier 120 is present, attachment mechanisms 171 and 173 can replace attachment frame or mechanism 167, or could be used in addition to attachment frame or mechanism 167. Another attachment mechanism 175 can be used to secure the relative positions of lens assemblv 1 15, boule 1 10, and CCD arrav 130. The attachment mechanisms 163, 167, 171 , 173, 175 mav also provide electπcal or other coupling between the elements.

Figure 3C shows a side view of boule 1 10 including input surface 151. As can be seen, input surface 151 includes a collection or bundle of fibers 147. Optical radiation is coupled to the input surface 151 from the lens assembly 115. Lens assembly 1 15 (Figure 3B) can be any combination of lenses which couples optical radiation 141 to input surface 151. Optical radiation is most efficientk coupled to fibers 147 if ravs represenπne the direcuon of travel of the optical radiation are incident as closely as possible to the normal j input surface 151 Boule 110 effectively reduces the size of an image at input surface 151 to a reduced image at output surface 157 to be detected bv CCD arrav 130 (Figure 3B). Cross-sectional area 151 a of input surface 151 need not necessaπlv be the same for each boule 1 10 Similarly, the cross-sectional area 157a of output surface 15^" need not be the same for each boule 110 The lengths L of boules 1 10 need not necessaπh be equal, but are approximately equal according to one preferred embodiment ot the invention \ddιtιonallv, according to one preferred embodiment, surface area 151 a can be vaπed to match anv optical assemblv depending on lens assemblv 1 15, the desired field of view, the dimensions of CCD arrav 130, and the desired resolution

Figure 3D shows a side view of fiber opuc taper assemblv group 1 Y capturing radiation 141a-141e to yield a seamless image \ composite field-of-view 181 is accomplished bv appropπate selection of individual ficlds-of-view 181 a- 181 e which correspond to individual fiber optic taper assemblies 1 2a- 102e, respectiveh Individual field-of-view 181 a yields an image 183a on (YD arra\ 1 0a Fiber optic taper assembly 102a achieves this in the manner discussed above with respect to Figure 3B That portion of optical radiation 141 which has optical

s whose direction is at the appropπate angles to be captured by taper assembly 102a are represented bv 141 a The same holds for optical rays 141 - 14 e and taper assemblies 102b- 102e, respectiveh

Figure 3E shows a top v iew ot an array series 187 made of CCD

s 130a-130e

\lso shown are images 183a captured from field-of-view 181 a (Figure 3D) and incident on

CCD arrav 130a as well as image 183b captured from field-of-view 181 b (Figure 3D) and incident on CCD array 130b. According to one preferred embodiment, fields-of-view 181a and 181b overlap each other along one composite field-of-view line 182 (Figure 3D). A composite field of view line is defined here to be any line, curved or straight, which can be drawn in space which always lies within an individual field-of-view The maximum angle continuously subtended by the individual fields-of-view will be referred to as the maximum composite field-of view. This is accomplished bv selecting appropπate lens assemblies taper- assemblies 102a and 102b

An overlap region 189 is shown over both CCD array 130a and CCD array 130b Overlap region 189 is capable of receiving certain rays of optical radiation which he in the field-of-view 181 a as well as in the field-of-view 181 b (Figure 3D) If individual fields-of- view 181a and 181b are selected to produce overlap region 189, then individual pixels 190a which receive radiation in overlap region 189 on CCD arrav 130a can be compared and aligned with individual pixels 190b in overlap region 189 on CCD array 130b in order to electronically provide a resulting seamless digital image. For example, according to one preferred embodiment of the invention, values of pixels 190a and 190b mav be averaged or weighted to vield a single pixel value for the final resulting composite digital image. If no such overlap region exists, the resulting composite digital image can have gaps and may not be continuous or seamless It should be understood in certain applications, that it may be desirable to select fields-of-view 181 a- 81 c to have no overlapping regions or which have predetermined gaps. Tins is especially true if fields-ot-view 181 a- 181 c are made particularly narrow while keeping the number of fiber optic taper assemblies 102a-1 2e fixed, thereby increasing resolution at each CCD array. Figure 3F shows fiber opuc taper assembly 102 with four very narrow fields-of-view

181 a- 181d. In this case, only four taper assemblies (not shown) are contained within taper assembly group 103. An x axis is shown in Figure 3F representing a fixed direction in space. If an object hes within field-of-view 181 a, then an image would appear at the corresponding CCD array and an observer would have a better estimate of angle θ with respect to the x axis, as shown in Figure 3F Fiber opuc assemblv group 103 can be made to rotate with an angular velocity ot ω to scan a 360° field-of-view. In other circumstances, it mav not be necessary to rotate fiber opuc taper assemblv 103 provided the area of observation can be selectively determined.

The number of CCD arravs can be two or greater. In the above examples, five CCD arrays were shown in order to achieve a sufficient resolution and composite field-of-view 181 which spans 180 degrees. However, the present invention is not intended to be so limited.

Referπng back to Figure 3 A, the fiber opuc taper assembly 103 is connected to a camera control system 40 which controls the digital camera svstem 100. The svstem 40 includes an image intensifier control unit 144 for controlling image intensifiers 120 and CCD arravs 130. The control unit 144 also includes frame grabber 148 which can include stitching software 150, which will be further descπbed below. The system 40 could also include the autogate exposure circuit 1 0 and power supply 162. In one preferred embodiment, the functions of the autogate exposure circuit 160 and the image intensifier control unit 144 could be performed by a single svstem. Furthermore, system 40 could include a microprocessor 169.

Also, system 40 includes a memory unit 142, which could be used to store the wide- angled images as well as other collected or processed data. The system 40 outputs a digital image bv stitching together the individual images from the fiber optic taper assemblies 102.

The svstem 40 can be further coupled to a transmitter 146 for sending captured images to a desired remote device, such as a satellite 70 or a remote station 72, shown in

Figure 2, or to anv other desired receiver. The transmitter 146 mav be included as part of system 40, or mav be separate such that the system 40 can be removed without removing the transmitter 146. Moreover, the system 40 can be coupled to a receiver 286 to receive information.

Addiuonalh , although the camera system 100 is shown with multiple CCDs 130, another preferred embodiment could include a single CCD arrav and multiple boules 110 and lenses 1 15. The single CCD array would be large enough to receive image data from each of the boules. The CCD arrav could be centrally located or positioned in a fixed position. Alternatively, one fiber optic taper assembly 102 could be fitted to the single CCD array, with the boules 1 10 from the other taper assemblies 102 being routed to the single CCD array. Similarly, there could be anv number of CCD arrays used to receive images from the boules. Fiber opuc boules 1 10 are πgidlv held together bv a mounting plate or holding structure (not shown i to keep the tapers pcrmanendv ahgned along respecπve optical center hnes and along the tocal plane. The plates mav include Kovar to ensure a proper thermal match for the fiber opuc glass because the thermal coefficient of expansion and contraction of the Kovar matches the thermal coefficient of expansion and contraction of the fiber optic glass. The plate can also be provided with mounting holes so that the fiber optic taper assembly 102 can be attached to an enclosure for the digital camera svstem 100. According to another embodiment, the boules 1 10 can be fused together to form a single block of fused boules.

The fiber opuc assembly 102 can either be πgidlv coupled to the camera svstem 100, or can be pliably mounted. If the taper assemblv 102 is phably mounted, it may be conformed or moved to be positioned in any direction. For example, the taper assemblv 102 could be wrapped in wire, coil, or a malleable mateπal such that the assembly's direction can

Y be set bv bending the assemblv to a desired locauon Alternatively, the taper assemblv 102 can be movablv mounted in 1, 2, or 3 dimensions, such that it can be positioned by hand or automaucallv (responding to a control system, moving to preprogramed locations, or bv user commands) to point to a desired direction. Moreover, anv combination of taper assemblies 102 can be fixedlv mounted with respect to another assemblv , and the fixed assembly groups can move independently of another fixed group, as described above. Alternatively, all of the assembhes can be xed and immobile with respect to each other, allowing all to move in unison, retaining their respective positioning The fixed assembhes can further be fixed to the camera system or can move while the camera svstem stavs fixed.

In anv of the above embodiments, the taper assemblv 1 2 can be configured without the CCD array 130 and/ or the image intensitiers 120 In this way, the lens 1 15 and boule 1 1 can be positioned independently' of the CCD arrav 130 and/ or the image intensitiers 120 The fiber opuc boules preferably reduce the images with less than 2° o geometric distortion, which is less than losses due to the elasticm of film. Light transmission losses are about 20° o, which is not ot degrading significance Future CCD technologv⁷ will allow tor larger arravs that require shorter tapers and reduced transmission losses. In this example, each of the five fiber optic tapers has a 45mm x 45mm input It is readily understood that other sized inputs are also available to the embodiments Specifically stated, each of the five fiber opuc taper assembhes 102 includes an image intensifier 120 coupled to the output of the respective fiber opuc boule 1 10. Each ot the image intensitiers 120 includes fiber opuc input and output windows A gated power supph 162 and control circuit 160 operates the intensitiers 120 and provides for auto-gaung the image intensifying photo cathode that will control proper exposure. The image intensifiers 120 and CCD arravs 130 are positioned on the minifying end

104 of the fiber opuc boules 1 10 The coupling between the fiber opuc boules 110, image intensifiers 120 and CCD arrays 130 allow replacement of any respective element without the need to replace all of the elements or the complete fiber opuc taper assemblv 102 Alternauvelv, anv of the elements could be combined. The CCD arrays 130 can be remote and connected to the main camera electronics via cables This allows anv CCD or CMOS for a compact assembly of digital camera electronics such as autogate exposure control circuit 160 and image intensifier power supplies 162 to be located at the site of each fiber optic boule 1 0, structurally isolated from the imaging optics. Mounting plates or holding structures (not shown) surround each fiber optic boule 110 and also shield stray light.

The active area of each CCD arrav 130 is therefore precisely coupled to the output of each respective fiber opuc boule 1 10. Each of the five fiber opuc taper assembh secuons 102 is ahgned along the respecuve optical center hnes bv a special precision procedure.

Additionally, the height of the digital camera svstem can be minimized bv mounung camera components oft either side of each fiber optic boule 1 0 with the CCD arrays 130 as the last item in the vertical stack.

The image intensifiers 120 with gateable power supphes 162 and exposure control circuitry 160 regulate the amount of light presented to the CCD arravs 130. These auto-gated image intensifiers 120 also function as electronic shutters for the digital camera system 100. The CCDs digitize the intensified images to a dynamic range ot, for example. 1 1 bits, and forward them to frame grabbers 148 (for example, in RS-422 format) located in the control unit 144 to be processed for display. Each fiber opuc taper assemblv 102 mav also include an analog output in RS-170 format to control the auto-gate of its image intensifier 120 and to allow a display of an analog image on a monitor. The analog image can be created bv stitching together each of the five images as described above and/or by using stitching software as descnbed below. Additionally, the output of anv one of the fiber optic taper assembhes 102 can be monitored The exposure control circuit 160 provides a constant video output by measuπng the input video level and maintains the proper pulse to the gateable intensifier power supply 1 2 Using the analog video, the exposure control circuit 160 controls the gate pulse so that the video level remains below saturation. Accordingly, the exposure control circuit 160 provides automatic exposure control for the image intensifiers 120, and therefore, for the enure digital camera system 100. The exposure control circuit 160 also provides the benefit of protecung the image intensifiers 120 and CCD arravs 130 from excessive light automaucallv without intervenuon of an operator. The digital camera system 100 can therefore achieve opucal gate pulses down to 50ns. The exposure control circuit can either be pan of svstem 40, or can be external to the system 40. Here, the image intensifiers 120 include a GaAs photo cathode having a minimum response of 1500μA/lumen, a luminous gain of 50,000-80,000 fL/fc, and a resolution of 51 to 64 hne pairs/mm. The image intensifier power supply 162 operates from 12-15VDC, for example, requiπng about one watt of power.

Each CCD array 130 according to one preferred embodiment of the invention requires about 15 wans of power, and includes a 1024x1024 volt frame transfer type sensor (not shown). The CCD arravs 130 operate at a frame rate of 15fps and have a cell size of

12mm x 12mm. Each CCD arrav includes a sensor remotely located from the main operating electronics via a short cable that attaches the CCD arrav sensor to the output of the image intensifier 120. This arrangement provides the benefit of isolating the structural load of the CCD electronics from the optical assemblv. Each CCD arrav 130 of this embodiment requires a power supply (not shown) capable ot providing +/ - 15VDC and +/-

5VDC.

Each of the CCD arra\ s 1 50 uses a frame grabber 148 for its operation The frame grabber 148 is located in the svstem 40 and operates under the control of the software 150. Images can be stored in the memory unit 142 and processed in standard Tagged Image File format (TIFF). Other formats could also be used.

Digital camera svstem 100 has a light sensitivity range of from about 10,000 Lux down to 10 ' Lux from day to night. Of course, these values depend on the light transmission of lens assembly 1 15. The values also depend upon the optical gate pulse produced at the image intensifiers 120. The bπghtest input is the maximum intensity to which the image intensifier 120 can be exposed with a minimum gate pulse of 50 ns. The lowest hght level is the minimal or darkest use peπod, to which the image intensifier 120 can be exposed with full camera frame exposure. Filters (not shown) in the input hght path, reduce hght input further when required.

As shown in Figure 3A, system 40 operates digital camera svstem 100 for image manipulation and display. System 40, for example, mav be a Dual PCI Bus Server Class

Computer with at least 8 PCI slots to handle the images from the five fiber opuc taper assembhes 102. It is understood that the system 40 mav be located within or physically separated from the enclosure of the fiber opuc taper assemblv 102 and corresponding auto- gating and integrates power supply circuitry. Software 150 stitches each of the five images together to make one composite image on, for example, a 225 x 45mm format view. The composite image has a field of view of over 180°, so that, for example, airplane 50 (Figure 2) can obtain an image of the ground below it from one horizon to an opposite honzon in one exposure.

As discussed above, the digital camera system 100 has advantages and uses in numerous different environments. The following section will discuss some of the additional benefits and uses of the digital camera svstem 100

Figure 4 illustrates another preferred embodiment of the invenuon including another exemplary embodiment of system 140. Svstem 40 (Figure 3A) is replaced bv svstem 140 in this preferred embodiment. At a minimum, however, system 140 can perform all of the basic funcuons as system 40 as previously descπbed. Additionally, since svstem 140 includes a transmitter 146' and a receiver 286', transmitter 146 and receiver 286 are opuonal. Figure

4 shows a svstem 140 for providing fhght informauon, fhght adjustments as well as for transmitting digital images or other processed information based on the digital images produced bv fiber opuc taper assemblv 103 or altcrnauveh digital camera svstem 100 as described above For purposes of claπty, only the camera 100 will be discussed. It is understood that the fiber opuc taper assemblv 103 could be subsututed.

Svstem 140 downloads image informauon produced bv the digital camera system 100. Reducer 230 can include a data compressor, intelligent data sampler, random data sampler, thresholders, digital filters as well as digital correlators and / or anv combination thereof Reducer 230 receives image information 212 and outputs modified informauon 214

235 can be used to display anv informauon contained in svstem 140. This mav include raw- image informauon received from digital camera svstem 101 ), or the modified informauon 214 or other informauon or data in s\ stem 140.

Image informauon 212 may also be directly input to a comparator 240 Comparator 240 can compare image informauon 212 with reference information 216 from database 220 for a vaπety of purposes including identification purposes. Modified informauon 214 mav also be compared to reference information 216 bv comparator 240 Database 220 can contain reference information 216 acquired using digital camera system 100, including the modified information 214 gathered over a period of ume. In addiuon, database 220 can contain other informauon downloaded into svstem 140 from an external source. Modified informauon 214 can also be output to fhght processor 260. Fhght processor

260 processes modified informauon 214 and outputs relevant fhght informauon such as airplane atutude, altitude (AGL or above ground level and/ or MSL or above sea level), air speed, ground speed, direction of fhght, vertical speed and/or other information

System 140 and fhght processor 260 can receive data from fhght instruments 280 in order to determine one or more of these parameters In addition, fhght processor 260 can output information 218 to fhght instruments 280 Fhght processor 260 can also output fhght informauon 218 to airplane control system 2⁷0. Fhght processor 260 can also receive fhght informauon 218 from airplane control svstem 270. Such informauon can be compared and used as a redundancy or double check of performance of the flight instruments as well as control of the airplane In addition, should certain flight instruments or other systems on the airplane malfunction, such informauon 218 mav be ot use as a backup to those instruments.

System 140 also can include a target analyzer 250 Target analvzer 250 can receive image informauon 212 direct! v and perform target recognition analysis using database 220

Target analvzer 250 mav include an artificial intelligence (Al ) unit 253 which can include neural networks Al unit 253 learns and/or develops a more effective target analysis and builds up database 220. Target analyzer 250 may compare reference information 216 to modified informauon 214 which is output from reducer 230 Target analvzer 250 recognizes small movements or differences in the successive images unrelated to the movement of the plane, and determines movement of objects within the target area in which the image was taken, such as an automobile moving down a road This intormauon is useful for determining changes in the object^'s (e.g., vehicle's) motion tor determining geoposiuon ot the object Alternatively, target analvzer 250 mav compare raw image data or image informauon 212 to reference informauon 216

Svstem 140 can include a transmitter 146' which transmits am of the prev iously discussed information via a tree space transmission hnk. Transmitter 146' may transmit the information via any type of electromagnetic radiation including RF, microwave, millimeter wave, and opucal wave such as infrared or visible, etc Transmitter 146' mav be direcuonal, hne of sight, or broadcast. Transmitter 146' mav include an encryption unit 248 which encrypts information output from transmitter 146' prior to transmission Transmitter 146' may also include a compression unit 249 to compress the data pπor to transmission. The transmitter 146' mav transmit information from svstem 140 to a satellite 271 which in turn sends that information to an earth station (not shown). Alternatively, transmitter 146' may transmit direcdv to an airborne object 273 such as an airplane, ghder, air balloon, hehcopter, or other object Transmitter 146' mav also transmit directly to a control or central stauon 275 which could be an earth station.

System 140 can also include a receiver 286' for receiving information from a remote location. Receiver 286' mav be configured to receive informauon from satelhte 2^ 1 , airborne object 273, or a central stauon 275. Such information mav include fhght control informauon to control direcuon ot flight such as would be used if no pilot were on the plane or an airborne object on which digital camera system 100 and svstem 140 are mounted Receiver 286' may also be configured to receive informauon from a locauon other than the location to which transmitter 146' is transmitπng Transmitter 146' and receiver 286' mav or may not use the same mode of transmission. For example, transmitter 146' mav transmit infrared raαhauon while receiver 286' receives microwave transmissions. Alternatively, transmitter 146' and receiver 286' mav be a single transceiver which both transmits and receives. Receiver 286' may further include some type of decompression unit 289 and decryption unit 291. The downloaded and reduced image data may be compared to other image information stored in a database 220 for tracking the movement of the airplane 50 (Figure 2) such as changes in airspeed, altitude, atutude and direcuon. Based on the results of the comparison, the svstem 140 can adjust the position of the plane via the airplane control system 270, and can forward the fhght information to flight instruments 280 based on compaπson results between an image and previous images bv the comparator 240

Figure 5 illustrates digital camera system 100 positioned on a helicopter 300 according to another embodiment of the invention As shown in Figure 5, the digital camera svstem can be mounted within or outside a profile of the hehcopter 300 because of the reduced size. Using the system 140 discussed above and shown in Figure 4, or another embodiment of the svstem 40, the digital camera svstem 100 records numerous images within a few seconds, and compares the results of the images for recognizing movement of a target. For example, the target could include a distressed person 310 swimming in a body of water 320 This approach provides the benefit of locaπng person 310 or other objects within a large geographical area quickly by gatheπng hoπzon-to-hoπzon image data, and detecung mouon within the lens assemblies' composite field-of-view. In vet another embodiment, the digital camera system 100 can operate in the infrared range to locate the object or person In this case, lens assembhes 1 15 and CCD arrays 130 would operate in the infrared spectrum and would be ideal for locaung the object or person at night.

Figure 6 illustrates another preferred embodiment of the present invention. As shown in Figure 6, the digital camera svstem 100 is positioned on an automobile 400 and is angled toward the rear of the automobile 400 for gatheπng wide-angled images of the regions next to and behind die vehicle. Svstem 140 (Figure 4) transmits image data to a driver of the vehicle 400 via, for example, a rear view mirror of the vehicle 400. A video monitor could replace or be used in conjunction with the well known rear view mirror, and could provide composite fields-of-view over 180° and up to 360° for certain apphcauons. The camera could be mounted on, but not in, the vehicle to provide images uninterrupted bv the dπver's bhnd spots. Accordingly, the dπver could observe vehicles to the side of and behind the vehicle 400 without visual obstructions

Figure 7 shows a digital camera svstem 701 according to another preferred embodiment of the invention. Digital camera system 701 includes two digital camera systems 100 and 700 Camera system 100 has a first composite field-of-view 181 and camera system

700 has a second composite field-of-view 781. Camera svstem 701 has a composite field-of- view 784 which is the sum of first composite field-ot-view 181 and second composite field- of-view 781. First composite field-of-view 181 is a composite field-of-view which includes the summation of fields-of-view 181 a-181e, and second composite field-of-view 781 is a composite field-of- view which includes fields-of-view 781a-781 e. Although Figure 7 shows camera svstem 100 with a composite field-of- view 181 equal to 180° and camera svstem 700 with a composite field-of-view 781 equal to 180°, composite fields-of-view 181 and 781 can be any value as previously discussed Similarly, although Figure 7 also shows composite field-of-view 784 equal to 360°, it can be anv value and need not necessarily be continuous as discussed above with reference to Figure 3F. Composite field-of-view 784 is the sum of fields-of-view 181 and 781 Again, the number of fiber opuc taper assembhes and their corresponding individual fields-of-view and the resulting composite fields-of-view can all be varied depending on a particular application The camera system 701 in Figure 7 shows individual fields-of-view 181a-181e, 781a-781 e to be approximately centered or ahgned in the z direction (the direcuon normal to the Figure 7) It should be understood, however, that any one of the assembly sections 102a-102e as well as 702a-702e mav be tilted in the z axis so that the respective fields-of-view would be at anv angles with respect to the z axis. For cercun apphcaαons with vehicles on the ground, it may be beneficial to scan a field-of- view in the view direction which is essentially coveπng a hoπzon up to 360°.

In the above discussed embodiments of digital camera system 100, the number of individual fiber opuc taper assembhes 102 as well as the number of CCD arrays 130 can be vaπed. In addition, the corresponding individual fields-of-view can be made to overlap or to "look^"' in any direcuon depending on the parucular apphcaπon. The resulting or composite field-of-view can be conunuous or not as discussed above

Figures 8A-8D provide several examples of composite fields-of-view Figure 8A shows a composite field-of-view ( or field-of-view pattern) 803 arranged on an x, y, z coordinate svstem for digital camera 100 Composite field-of-view 803 includes individual helds-of-view 807a-d. As can be seen, the angular dimension of individual fields-of-view 807a-d mav be different. For example, individual field-of-view 807a is a symmetrical column with a representative direction 81 1 and an angle θ with respect to the x axis in the xy plane and an angle φ down from the z axis Fields of view 807b-d may not be symmetric with respect to a single direcuon as is the case tor field-of-view 807a. For example, field-of-view

807b shows a column with a cross secuon in a shape of a rectangle rather than a circle. This can be accomplished bv using cylindrical rather than spherical lenses in lens assembly 115 (Figure 3A). Again, the desired field of view pattern depends on the apphcauon as discussed, for example, with respect to Figure 5 and Figure 6. In the digital camera svstem 100 discussed abov e, the fields of view are ahgned such that CCD arrays 130 are in proximity to each other. In an alternative embodiment, fiber opuc taper assembly 102 can be posiuoned a distance Z„ as shown in Figure 8B Here, composite field of view 813 includes individual ficlds-of-view 817a and 817b. In a general arrangement, there may be points in space such as point P and which subtends field-of- view 817b but not field-of- view 817a or vise versa. There mav be other points such as point T which is subtended bv both field-of-view 817a and field-ot-view 817b. In this case, point T will appear at different locations on fiber optic taper assemblv 102a and 102b, respectively. This approach may be used in conjunction with svstem 140 of Figure 4 to identify which CCD array 130a or 130b (Figure 3E) has the better '^"view" of the object in question. Svstem 140 can then selectively analyze data on the CCD array with the better view of object T. For example, if field-of- view 817b provides a better view of the object than field-of-view 817a, then system 140 can selectively analyze informauon output from CCD array 130b in more detail than informauon output from CCD array 130a For example, reducer 230a can selecuvelv reduce informauon received from CCD arrav 130a in camera svstem 100 and avoid reduction or perform less reducuon ot informauon received from CCD arrav 130b. It should be understood that fiber opuc taper assembhes 102a and 102b (or more if necessary) can be spaced at any point on an aircraft, vehicle, or structure as desired.

Figure 8C shows fiber opuc taper assembhes 102a and 102b spaced a distance Z₍₎ according to another embodiment of the invention in which fields-of-view 817a and 817b are made to overlap or nearly overlap the same areas Here, points or objects T offer the most part observed or viewed bv both fiber opuc taper assembhes 102a and 102b for all such points T. However, since fiber opuc taper assembhes 102a and 102b are separated by a distance Z₍₁, then in effect provide stereographic viewing or imaging In other words, respecuve pixels on CCD arravs 130a and 1 30b in fiber opuc taper assembhes 102a and 102b are looking for viewing the same points in space at different angles, thereby providing three dimensional imaging capabihues. This in turn allows svstem 140 (Figure 4) to perform target analysis or recognition using target analvzer 250 on three dimensional objects. Database 220 could also store portions or entire three dimensional objects for compaπson purposes by comparator 240.

Figure 8D shows a composite field-of-view 827 which is in the shape of a cone which does not completely cover a surface 837 but instead covers an annular ring defined by the angles between and including θ, and θ_: The hatched region 839 would not be within field- of-view 827. Again, composite field-of-view 82~ would include multiple individual fields-of- view and hence would result from a digital camera 100 with multiple fiber optic taper assemblv 102.

All of the composite fields-of-view or field-of-view patterns discussed above are considered as example embodiments only, it being understood that the particular apphcauon for which camera 100 is intended determines a desired composite field-of-view or field-of- view pattern. Camera 100 could be used in manufactuπng systems which would call for certain surfaces to be analyzed. Assembly hnes, surveillance, and security camera apphcaαons would all require different or particular composite fields-of-view or field-of-view patterns Also, tacucal verses strategic purposes would also be factors used to determine the desired composite field-of-view or field-of-view pattern. All of the above discussed composite field-of- views and field-of-view patterns can be made to change direcuon individually or synchronously according to another embodiment of the invention In particular. Figure A shows another preferred embodiment of a digital camera 900 with fields-of-view which can be controllablv varied in direction using field-of- view (FOV) controller 901 with motors 902a-902c coupled to fiber opuc taper assembhes

102a- 102c respecπvelv . In this preferred embodiment according to the invenuon, the entire fiber optic taper assembhes 102a- 102c are rotated including their respective CCD arrays 130a-130c (not shown). Rotauon mechanisms or motors 902a-902c can be stepper motors which respond to digital commands received from FOV controller 901. FOV controller 901 can be coupled to svstem 140 (Figure 4) discussed above. Hence, when the target or object enters into an individual field-of-view 817a, system 140 can recognize the target using target analvzer 250 and further provide automatic command via hne or bus 923 to FOV controller 901 which in turn commands stepper motor 902b to adjust an angle of viewing of the field- of-view such that the target of interest is in the center or more centered in the field of view. Alternatively, an input unit 927 can be used by an individual viewing display 235 in a manner such that the individual can control the area viewed bv the fiber opuc taper assemblv 102a. If the individual sees an object of interest at, for example, a left of field-of-view 817a, he or she can use input unit 927 to move fiber opuc taper assembly 102a so that the object of interest comes into or hes completely within field-of-view 817a. Input unit 92⁷ may include a computer with an input device, such as a mouse or jovsuck. a voice command recognizer, or anv tvpe of steering mechanism

Figure 9B shows a digital camera system 950 with lndependentlv controllable individual fields-of-view 817a and 817b according to another preferred embodiment of the invention. Fiber optic taper assembhes 102a and 102b include lens assembhes 1 15a and 115b with CCD arrays 130a and 130b, respectively. Lens assembhes 1 15a and 1 15b are coupled mechanically and/or attached to boules 1 10a and 1 10b via attachment mechanisms 163a and 163b, respecuvelv. A mounung board 955 is used to mount CCD arravs 130a and 130b. In this manner, CCD arrays 130a and 130b can be rigidly affixed and do not change position with respect to each other. Mounung board 955 can be any mechanism which affixes CCD arrav 130a and 130b so that thev do not move while the directions of their respective fields- of-view 817a and 817b independendy vary. Fiber opuc taper assembhes 102a and 102b further include direcuon controllers 957a and 957b electronically coupled to a field-of-view controller 901. Direcuon controllers 957a and 957b can be anv type of stepper motor or ball bearing based attachment responsive to commands from field-of-view controller 901. Svstem 140 is electronically coupled to field-of- view controller 901, it being understood that system 140 could include field-of-view controller 901. Direction controllers 957a and 957b are mechanically attached to boule 110a with lens assemblv 163a as well as to boule 1 10b with lens assembly 1 15b via mechanical couphngs mechanism 961 a and 961b, respectively. Commands from field-of view controller 901 are sent to direcuon controllers 957a and 957b which in turn rotates boules 1 10a and 110b independendv, thereby resulung in independent changes in direction ot individual fields-of-view 817a and 817b, respecuvelv. Direction controllers 961 a and 961 b can change the general direcuon R that is shown in Figure 9B which can be represented in polar coordinates bv the angles φ with respect to the z axis and θ with respect to the x axis. The origin of the coordinates svstem defining the direcuon R is the point about which boule 1 l ϋa or 1 10b does not rotate or move while lens assembly 1 15a or 1 15b together with the remaining poruons of 1 10a or 1 10b are moving. In one preferred embodiment of the invention, attachment mechanism 171 a and 171 b affix d e relative posiuons of output surfaces 157a and 157b of boules 1 10a and 1 10b with respect to CCD arravs 130a and 130b, respecuvelv. In this manner, optical couphngs between outer surface 157a and CCD arrav 1 30a remains fixed or constant regardless of the direcuon R of individual field-of-view 817a The same holds for anv other boules such as boule 1 10b in digital camera 950.

The foregoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily apphed to other types of apparatuses. The descπpuon of the present invention is intended to be illustrauve, and not to limit the scope of the claims. Many alternatives, modifications, and vaπauons will be apparent to those skilled in the art. In the claims, means-plus-funcuon clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures For example, although a nail and a screw may not be structural equivalents in all environments in that a nail employs a cyhndπcal surface to secure wooden parts together, whereas a screw employs a hehcal surface, in the environment of fastening wooden parts, a nail and a screw mav be equivalent structures. Similarly, although a satelhte dish, a radio frequency (rf) antenna or IR lenses may not be structural equivalents in all environments in that a rf antenna mav be a wire, an IR lens employs lenses of certain mateπais and a satelhte dish employs a piece shaped as a dish, in the environment of informauon transmission (for example, transmitter 146' of Figure 4), an IR lens, an rf antenna and a satelhte dish mav be equivalent.

Claims

WHAT IS CLAIMED IS

1. A camera, compπsing: a plurality of lens assembhes, each of said plurality ot lens assembhes having a respecπve individual field-of-view and said plurality of lens assembhes yielding a composite field-of- view; a plurality of fiber opuc bundles respecuvelv optically coupled to said plurality of lens assembhes, each of said fiber opuc bundles having an input surface and an output surface; a plurality ot detector arrays respecuvelv optically coupled to said plurality ot fiber opuc bundles; and a camera control system coupled to said plurality of detector arrays, said camera control svstem configured to control acquisiuon and output of image intormauon from said plurality of detector arravs.

2. The camera as claimed in claim 1 , wherein said camera control system comprises a control unit and a memory unit, wherein said control unit includes a frame grabber unit configured to receive detector data from said plurality ot detector arrays and to store the detector data in said memory unit.

3. The camera as claimed in claim 2, further compπsing a transmitter coupled to said camera control svstem, said transmitter configured to receive said detector data and to modulate a earner signal with said detector data and to output said carrier signal for reception at a remote location.

4. The camera as claimed in claim 1 , further comprising: an exposure control unit; and a plurality of image intensifiers coupled to said exposure control unit and respecuvelv arranged between said plurality of fiber optic bundles and said plurality of detector arrays, each of said plurality of image intensifiers independently controlling intensity of an image on the respective detector array.

5. The camera as claimed in claim 1 , wherein said plurahrv of lens assembhes are arranged such that each individual field-of- view overlaps another individual field-of-view to yield a plurahrv of overlap regions at the output surfaces of said plurality of fiber opπc bundles and said plurahty of detector arravs are arranged such that each of said plurahty of overlap regions are detected bv at least two detector arravs.

6 The camera as claimed in claim 1 , wherein said plurahty of lens assembhes, said plurahrv ot fiber optic bundles and said plurahty of detector arravs are arranged to have a maximum composite field-of-view of at least approximately 180 degrees

The camera as claimed in claim 1 , wherein said plurahty of lens assembhes, said plurahrv of fiber opuc bundles and said plurality of detector arravs arc arranged to have a maximum composite field-of-view of at least approximately 360 degrees.

8. The camera as claimed in claim 1 , further compπsing a direcuon controller coupled to one of said plurahrv of fiber opuc bundles, and a field-of-view controher electncallv coupled to said direcuon controller, said field-of-view controller outputung position intormauon to said direcuon controller, said direcuon controller adjusung the posiuon of one of said plurality fiber opuc bundles and the respective lens assembly in accordance with said posiuon intormauon, thereby varying the respecuve individual field-of- view