WO2017162603A1

WO2017162603A1 - Illuminating device for analysing an object having at least one reflective and/or transparent polished surface and associated system

Info

Publication number: WO2017162603A1
Application number: PCT/EP2017/056590
Authority: WO
Inventors: Frédéric Bourcier
Original assignee: Centre National D'etudes Spatiales
Priority date: 2016-03-21
Filing date: 2017-03-20
Publication date: 2017-09-28
Also published as: FR3049043B1; FR3049043A1

Abstract

The invention relates to an illuminating device for analysing an object having at least one reflective and/or transparent polished surface, characterised in that said device comprises at least one light source (10, 18, 32, 42) capable of illuminating the object to be analysed at a predetermined angle of illumination when the object is positioned at a predetermined location, said polished surface being orthogonal to a viewing direction and inside the field of view for observing the object, and at least one reflecting or diffusing absorber (14, 16, 34, 36), said absorber being positioned with respect to said light source in such a way that the rays of light coming from said source which do not reach said polished surface or which are reflected by said polished surface are captured by said absorber.

Description

Illumination device for object analysis having at least one reflective and / or transparent polished surface and associated system

The present invention relates to an illumination device for object analysis having at least one reflective and / or transparent polished surface.

The invention lies in the field of the analysis of objects having polished surfaces, and in particular the quality inspection of such objects.

Examples of such objects to be analyzed are for example: mirrors, anti-glare glasses, filters, slides for various laboratory applications, optical lenses.

Such objects can be affected by very slight disturbances, for example very fine scratches, molecular or particulate contaminations, detachments (for example detachment of a filter on an optical glass) or fingerprints.

It is useful to identify and analyze such defects in a reproducible and quantifiable way. For example, a systematic quality inspection may be necessary for optical products, for example glasses for spectacles or for optical instruments, for example telescopes.

A visual control by an operator is difficult and not quantifiable nor reproducible. In addition, there is a problem of observation conditions, including lighting. Indeed, the lighting in a room varies, and in addition the visual inspection of polished surfaces is particularly difficult.

It is therefore useful to develop a device and a system of analysis of polished surfaces which allows to obtain a reproducible, reliable result, independent of the ambient and uniform lighting.

For this purpose, according to a first aspect, the invention proposes an illumination device for object analysis having at least one reflective and / or transparent polished surface.

This lighting device comprises at least one light source capable of illuminating the object to be analyzed according to a predetermined illumination angle when the object is positioned at a predetermined location, said polished surface being positioned so as to be orthogonal to a the aiming direction, and within an object observation field of view, and at least one reflecting or diffusing type absorber, said absorber being positioned with respect to said light source so as to that light rays from said source, which do not reach said polished surface or which are reflected by said polished surface, are picked up by said absorber.

Advantageously, the proposed lighting device makes it possible to illuminate with a very high contrast the polished surface to be analyzed and to absorb all the other light rays so as to avoid any disturbance of the observations by the shooting environment. In embodiments, the object analysis illumination device according to the invention further comprises one or more of the following features, taken independently or in any technically feasible combination.

It comprises a first point light source, positioned outside the field of view, inclined with respect to a direction perpendicular to the viewing direction at a first inclination angle so as to substantially uniformly illuminate said polished surface of the object to analyze.

The first light source has an emission axis, and the device comprises a lens positioned perpendicularly to the emission axis of the first light source.

It comprises a first reflective type absorber, positioned at a second angle of inclination with respect to the direction perpendicular to the aiming direction so as to capture all the light rays from the first light source and to reflect some of the rays of light incident outside the field of view.

It comprises a second reflective type absorber, positioned at a third angle of inclination relative to the direction perpendicular to the direction of sight, so as to capture all the light rays reflected by the object to be analyzed and to reflect a part light rays incident on said second absorber outside the field of view.

It comprises a second light source capable of illuminating substantially perpendicular to the direction of view, and an inclined semi-transparent plate positioned to capture a beam of light rays emitted by the second light source and to reflect a portion of rays of light incident towards the surface of the object.

The device comprises a third light source, said third source being positioned to illuminate the object to be analyzed in transmission in the aiming direction.

The device comprises a fourth light source, positioned outside the field of view of observation, and able to illuminate the object to be analyzed according to a predetermined inclination.

According to one embodiment, it comprises a housing, with internal walls covered by a uniform matte coating, comprising an opening in a first wall, said opening corresponding to the field of view of observation.

The or each inner wall of the housing is adapted to absorb a first percentage of incident light and to diffuse a second percentage of incident light on said the second percentage being at least ten times smaller than the first percentage.

The housing has lateral openings, for successively positioning a plurality of objects to be analyzed in said housing at said predetermined position.

The housing is of parallelepipedal shape and two side walls located opposite each other are absent from said housing.

According to another aspect, the invention relates to an illumination system for object analysis having at least one reflective and / or transparent polished surface, characterized in that it comprises lighting device as briefly described above and a camera whose lens is positioned in front of said aperture, the camera being able to capture at least one image representative of said polished surface of the object to be analyzed. Advantageously, the captured image is clear throughout the field of view.

In another aspect, the invention relates to the use of a lighting system as briefly described above in a method of automated inspection of a polished reflective and / or transparent object surface.

Features and advantages of the invention will emerge from the description which is given below, by way of indication and in no way limitative, with reference to the appended figures, among which:

FIG. 1 schematically represents an illumination system for object analysis having at least one polished reflective and / or transparent surface according to one embodiment;

- Figure 2 schematically shows a sectional view of a lighting device according to a first embodiment of the invention;

- Figure 3 schematically shows a sectional view of a lighting device according to a second embodiment of the invention;

- Figure 4 shows schematically a sectional view of a lighting device according to a third embodiment of the invention;

FIG. 5 schematically represents a sectional view of a lighting device according to a fourth embodiment of the invention, and

- Figure 6 schematically shows a sectional view of a lighting device according to a fifth embodiment of the invention. Figure 1 schematically illustrates an illumination system 1 for object analysis having at least one reflective and / or transparent polished surface, according to an embodiment of the invention.

The system comprises a lighting device 2 of parallelepipedal shape, and a camera device 4, for example a camera, the lens of which is positioned at an aperture 8 made in a corresponding wall of the housing 6. of the lighting device 2.

Advantageously, a standard camera is usable.

The opening 8 makes it possible to define an observation field of view of said object surface to be analyzed, the depth of field being adjustable by adjustment of the camera. A line of sight A is also defined, which is the line of sight of the camera.

As shown in transparency, an object E to be analyzed, comprising a polished surface S, is positioned perpendicularly to the line of sight A (collinear with the Y axis of the reference (Χ, Υ, Ζ) of FIG. a predetermined location.

The illumination of the object E is thus a coaxial illumination with respect to the shooting.

The positioning of the camera also defines a direction of sight, indicated by the arrow on the line of sight A in Figure 1.

The object E has a given thickness and a base of any geometric shape. In the example of Figure 1, its base is rectangular, but any other form is possible.

Preferably, a not shown fastening support makes it possible to keep the object E at the predetermined location, in the field of view of the camera.

The housing 6 of the lighting device 2 has, in the illustrated embodiment, the shape of a parallelepiped, or, alternatively, a cube, whose base and height have given dimensions.

Preferably, the dimensions are chosen according to the maximum dimensions of the objects whose surface is to be analyzed.

In addition, these dimensions are chosen so that the field of view of the camera is either uniformly illuminated or evenly extinguished in the field of view, without stray light returning to the first order at less. It should be noted that in the embodiment illustrated in FIGS. 2 to 6, thanks to the positioning of the absorbers described in detail below, second-order parasitic light extinction is obtained.

For example, a lighting device 2 has dimensions of 30 cm in height, for a base of 15x15 cm ² or 20x20 cm ² for the inspection of objects of maximum dimensions 20x20 mm ² .

It should be noted that all the elements of a lighting device 2 are not shown, they will be described in detail below with reference to Figures 2 to 6 according to the various embodiments envisaged.

FIG. 2 diagrammatically illustrates a lighting device 2 according to the invention in a first embodiment of backscattering lighting, allowing the re-illumination of backscattered light rays by non-specular diffusing elements deposited on a highly specular surface on an object to be analyze, for example a mirror or an optical filter.

FIG. 2 represents a cross-sectional view in a horizontal plane (X,

Y) of a lighting device 2, comprising a rectangular frame 6, comprising walls 6a, 6b, 6c, 6d.

The walls 6e and 6f, visible in FIG. 1, are not visible in FIGS.

6.

The internal faces of the walls are covered with a uniform matte coating, preferably black, so as to maximize the absorption rate of light rays.

In one embodiment, only one of the walls, denoted 6a, has an opening 8.

In one embodiment, the opening 8 has a circular shape, as illustrated in FIG.

According to the illustrated embodiment, the opening 8 has a tubular side wall 8a for limiting the amount of external light entering the housing.

FIG. 2 also shows, by way of example, an object E to be analyzed, of width L equal to or less than the illuminated area.

The device 2 comprises a first source 10 of white light, positioned on or near the first wall 6a, also called the first wall, in which the opening 8 is made. The source 10 is a point light source having an axis emission B and emitting a beam F of light rays in the direction of the object E covering only the useful area through a lens 12 shaping the lighting 10, to illuminate only the surface of the object E uniformly. Preferably, the lens 12 is positioned perpendicularly to the emission axis B of the light source 10, which is oriented so as to emit rays with an angle of incidence α with respect to the X direction, greater than or equal to at a minimum angle of incidence ototel the illuminated area projected on the absorber 14 is out of the field of view of the camera.

Advantageously, the light source 10 does not need to be collimated, the lens 12 limiting the extent of the beam F to an opening angle.

Preferably, the light source 10 consists of light-emitting diodes. Alternatively, any other light source may be used, for example filament lamps.

The light source 10 and the positioning of the object E to be analyzed with respect to the opening 8 are determined so that the surface S of the object E is illuminated uniformly.

A part of the light rays of the beam F, diagrammatically represented by the rays F-1 and F _n in FIG. 2, does not reach the object E to be analyzed.

As illustrated in the figure, each of the radii F _1; F _n reaches a first absorber reflective 14, having a glossy coating of dark color, preferably black, which is positioned so as to capture all the light rays coming from the source 10 and to reflect a portion toward the inner walls of housing, the wall 6d in the example. The absorber 14 has the capacity to absorb a first percentage Pi of the incident light, for example Ρ _{1 =} 95%, the rest, percentage P ₂ = 5%, being reflected towards the wall 6d. More generally, P ₁ + P ₂ = 100%, Pi being preferably greater than 90%.

For the incident ray F _1; a reflected ray F'- is reflected towards the inner wall 6d, and likewise for the incident ray F _n , a reflected ray F ' _n is reflected towards the inner wall 6d.

The wall 6d is absorbent of a given percentage P ₃ , of the order of 95%, of the light received. A very small part, of the order of P ₄ = 5%, is scattered, as illustrated by the dashed arrows in FIG. 2. Since the quantity of light scattered is small, it does not illuminate the object E to be analyzed. .

In addition, a portion of the rays F, reaching the surface S of the object E to be analyzed is scattered in a radius F ', indicating the presence of a defect or an impurity on the observed surface.

The reflective absorber 14 is positioned at a given angle β with respect to the wall 6c, opposite the wall 6a on which the light source 10 is positioned, the angle β and the size of the absorber 14 being chosen so that the illuminated area the absorber 14 is out of the field of view of the camera or more generally from the field of view of observation. More generally, the angle β is the angle formed between the reflecting absorber 14 and the X direction of the reference mark shown in FIG.

The dimensions of the reflecting absorber 14 are chosen according to the minimum and maximum dimensions of the object E to be analyzed, and the dimensions of the housing.

The distance and the focal length of the camera to have the object E in the open field make it possible to calculate the distance between E and the first reflecting absorber 14 taking into account the triangle formed between the camera, the object E and the camera. source 10. It is understood that depending on the maximum dimensions of the objects E to be analyzed, one can build a suitable device by applying the principles of the invention.

The device 2 also includes a second reflecting absorber 16, having a dark, preferably black, shiny coating, which is positioned to capture all light rays reflected from the surface S. The reflected light rays F absorber 16 and are reflected in radii

F. to another inner wall of the housing, which is the wall 6b opposite the wall 6d.

Preferably, the second absorber 16 has the capacity to absorb a first percentage ΡΊ of the incident light, for example ΡΊ = 95%, a second remaining percentage 2 being scattered, for example P ' ₂ = 5%. More generally, ΡΊ + Ρ ' ₂ = 100%, ΡΊ being preferably greater than 90%.

The absorption percentage du of the second absorber 16 may be equal to or different from the absorption percentage of the first absorber 14.

As explained above, the wall 6b also absorbs about 95% of the light, and 5% is scattered as illustrated schematically in FIG.

The second absorber 16 is positioned in the example of FIG. 2 bearing on the wall 6b and at an angle γ with respect to the direction X in the coordinate system (Χ, Υ, Z), so as to capture all the radii of light reflected by the surface S of the object E.

The positioning angle γ depends on the dimensions of the various elements, in particular on the position of the object E and the source 10.

Proper positioning can be obtained by calculation or experimentation.

The dimensions of the reflecting absorber 16 are chosen according to the minimum and maximum dimensions of the object E to be analyzed, and the dimensions of the housing.

More generally, the second reflecting absorber 16 is positioned so as to capture all the light rays reflected by the object to be analyzed and reflected. a portion of the light rays incident on said second absorber to one of the inner walls of the housing.

Advantageously, thanks to the presence of the two reflecting absorbers 14, 16 the extinction of the light inside the housing of the device 2 is completely controlled.

The rays of light R are the rays captured by the camera.

Thus, when the surface S of the object E is flawless, the image captured by a camera 4 is uniformly dark.

If a fault is present, some of the light is scattered. Any defect is revealed by a lighter job appearing on the image captured by the camera, when shooting is performed with a sufficiently long exposure time.

Of course, a suitable adjustment of the camera for focusing on the object E to be analyzed is performed, so as to focus on the entire surface S of the object E.

Advantageously, it is easy to characterize any defect by its size and shape.

For example, scratch-like defects will be revealed as elongated clear lines. An anti-glare treatment detachment will also be visible, and its shape can be characterized.

The first embodiment described above is particularly suitable for inspecting defects on a mirror surface or transparent antireflection films.

FIG. 3 represents a cross-sectional view in a horizontal plane (X, Y) of a lighting device 2 according to a second embodiment of the invention, reference 20 in this figure.

The lighting device 20 comprises elements similar to those of the lighting device 2 of FIG. 2, for which the references are retained, in particular the housing 6, the first reflecting absorber 14 and the second reflecting absorber 16.

The device 20 comprises a second light source 18 positioned on or near the wall 6d in the example, and able to illuminate a semi-transparent plate 22 which illuminates the object E coaxially with respect to the axis of referred to A of the camera.

The light source 18 is wide and not punctual, a lens 24 being positioned in front of this source in order to limit the extent of the beam from the source so as to uniformly illuminate the object E.

Preferably, the second light source 18 consists of light-emitting diodes. Alternatively, any other light source may be used, for example filament lamps. The semi-transparent plate 22 reflects a part F 'of a ray of light F coming from the source 18 towards the surface S of the object E. A part F "of the ray of light F is transmitted by the blade semi-transparent to the second absorber 16, the operation of which has been described above with reference to FIG.

Thanks to the semi-transparent plate 22, the surface S of the object E is illuminated uniformly.

The rays of light passing through the object E or the radii F _k passing around are absorbed by the absorber 14, and a small portion is reflected towards one of the walls 6c or 6d.

The angle inclination β of the absorber 14 ensures entrapment of the incident rays and consequently a high extinction rate of the stray light reaching the object E.

Therefore, only the light reflected by the surface S of the object E to be analyzed is captured by the camera.

This makes it possible to observe the uniform reflection of the surface, and delamination-type treatment defects. In particular, this embodiment is adapted to detect any defect of an antireflection treatment applied to a glass surface, any antireflection defect inducing a variation of radiometry on the captured image.

In the absence of any defect, the image obtained is totally uniform.

A color variation of an interference filter in the field of view may reveal a variation in thickness of the thin layers that constitute it. For example, the appearance of colored fringes may reveal the presence of an air gap between thin layers, that is to say a delamination of thin layers, or the presence of a liquid film.

FIG. 4 represents a cross-sectional view in a horizontal plane (X, Y) of a lighting device 2 according to a third embodiment of the invention, referenced 30 in this figure.

The lighting device 30 comprises elements similar to those of the lighting device 2, for which the references are retained, in particular the housing 6 and the second absorber 16.

The device 30 comprises a third light source 32, which is a large source of white light positioned on the wall 6c, located opposite the opening 8, and able to illuminate the object E in transmission.

The geometric extent of the light source 32 is sufficient to illuminate the object E uniformly. In addition, the extent of the source 32 covers the field of view of the camera. Preferably, the third light source 32 is directional consisting of light-emitting diodes. Alternatively, any other light source may be used, for example filament lamps.

The device 30 comprises a diaphragm 34, preferably circular, which limits the direct parasitic light in the field of view. Preferably, the diaphragm 34 is a matt black diffusing absorber.

The light rays G, which pass around the object E are absorbed by the second absorber 16, and a portion G 'is reflected by this absorber to one of the walls of the housing, the wall 6b in the example.

Optionally, a second annular diaphragm 36 is positioned in the housing to absorb the remainder of light. Preferably, the diaphragm 36 is a matt black diffusing absorber.

By using this lighting device 30, only the light transmitted by the object E to be analyzed is picked up by the camera. Thus, it is possible to precisely determine the areas of non-uniformity of the object E, especially the delamination zones. A color variation of an interference filter in the field of view may reveal a variation in thickness of the thin layers that constitute it. For example, the appearance of colored fringes may reveal the presence of an air gap between thin layers, that is to say a delamination of thin layers, or the presence of a liquid film. The colors observed are complementary to the previous lighting (figure 3) for the interference filters.

FIG. 5 represents a cross-sectional view in a horizontal plane (X, Y) of a lighting device 2 according to a fourth embodiment of the invention, referenced 40 in this figure.

The lighting device 40 comprises elements similar to those of the lighting device 2, for which the references are retained, in particular the housing 6 and the second absorber 16.

The device 40 has a fourth light source 42, which is a source of point white light positioned on the wall 6c, outside the field of view of the camera. In one embodiment, the fourth light source 42 is an annular source disposed around the third light source 32. A diffusing absorber type mask 46 is positioned on the third light source 32 to avoid reflection. of light through the surface of the light source 32.

The fourth source 42 transmits towards the object E to be analyzed, with an angle of inclination with respect to the predetermined location of the object E, and the illumination of the surface of the object is almost uniform. Preferably, the fourth light source 42 consists of light-emitting diodes. Alternatively, any other light source may be used, for example filament lamps.

The diaphragm 34 limits the direct stray light.

A film of micro-droplets 44 located on the surface of the object E diffuses the light, this diffusion being imaged by the camera positioned in the field of view. A larger drop in size behaves like a lens and refracts light to the camera.

FIG. 6 illustrates a fifth embodiment of a lighting device 60 according to the invention.

This lighting device comprises a set of elements for successively operate all the embodiments described above.

It comprises a housing 6, a first light source 10, a second light source 18, a third light source 32 and a fourth annular light source 42.

Each of the light sources can be controlled to be turned on or off, depending on the desired lighting mode for an object to be analyzed E.

Optionally, diffusing absorber type masks are also provided to prevent any reflection of light from the surfaces of the light sources when they are extinguished.

The device 60 also comprises a first absorber 14, a second absorber 16, a first annular diaphragm 34, and a second annular diaphragm 36.

The elements 14, 16, 34 and 36 are removable, housing being provided for positioning each of these elements.

The positions and dimensions of the elements 14, 16, 34 and 36 are provided as explained above, depending on the dimensions of the housing and the minimum and maximum dimensions of the object to be analyzed.

Advantageously, in this embodiment, it is possible to successively obtain several images representative of the surface of the object analyzed by changing the lighting mode, each image being indicative of certain types of defects. Thus, additional information relating to the surface of the object E is obtained.

Advantageously, no displacement of the object E and no change of focus is necessary. The lighting device 2 has been described above in one embodiment in which the housing has a parallelepipedal shape.

As a variant, the housing of the lighting device 2 has another geometrical shape, for example a cylindrical shape, with an internal wall covered with a uniform matte coating, preferably black, so as to maximize the absorption rate of light rays. .

Any other geometric form is conceivable.

According to another variant, the lighting device according to the invention does not comprise a housing. This embodiment is suitable when the lighting device is used in a dedicated space, without stray light source, for example a dark room.

In this embodiment, the lighting device according to the invention comprises a first light source 10 and / or a second light source 18 and / or a third light source 32 and / or a fourth annular light source 42 .

The light sources 10, 18, 32 and 42 are positioned as described in the above embodiments, depending on the intended location of the object to be analyzed, and the maximum dimensions of the object to be analyzed.

The illumination device also comprises, in this embodiment without housing, a first absorber 14 and a second absorber 16, a first annular diaphragm 34, and a second annular diaphragm 36.

The elements 14, 16, 34 and 36 are positioned as explained above as a function of the observation field of view, the maximum dimensions of the object or objects to be analyzed, and the location provided for the object to be analyzed. provided that the surface S of the object to be analyzed is entirely within the field of view of the camera.

Each of the elements 14, 16, 34, 36 is held by a suitable support in the predetermined position.

The first absorber 14 is positioned so that the illuminated area projected on the absorber 14 is out of the field of view.

The second absorber 16 is positioned so that light rays reflected from the surface of the object E when illuminated by the source 10 are reflected out of the field of view. The annular diaphragms 34, 36 have, as in the embodiments described above, the role of limiting the illumination field of the sources 32, 42.

It should be noted that a device as described above in its various embodiments is integrable into a production line for a systematic inspection of the quality of objects produced.

In such a case, for objects of similar size and shape, a single preliminary adjustment of the camera's shooting parameters is performed, the objects to be analyzed being successively positioned at the determined location in the camera body. of the device 2, 20, 30, 40, 60.

In an alternative embodiment, the housing of the device 2, 20, 30, 40, 60 is an open housing, having openings in the walls corresponding to the internal walls 6e, 6f, or alternatively, an absence of the side walls corresponding to the internal walls 6e, 6f, or more generally an absence of two side walls located vis-à-vis one with respect to the other.

These openings allow the mounting of such a lighting device on an industrial chain, allowing the successive positioning of objects to be analyzed at the location provided for the object E, for analysis and systematized inspection of their surfaces.

For example, the lighting device according to the invention is positioned in such a way that a conveyor belt transports and positions the objects to be inspected at the intended location.

In one embodiment, the treadmill is transparent.

According to other variants, when the housing has another geometric shape than a parallelepipedal shape, appropriate openings are made to mount the lighting device so as to allow the successive positioning of objects to be analyzed at the location of the object E.

Thus, the lighting device according to the invention can be used in an automated industrial inspection / quality control process for possible surface defects of any reflective and / or transparent polished surface object.

For example, the inspection of glasses of any type, for example spectacle lenses, and various treatments (anti-reflective for example) is one of the applications envisaged.

The illumination device for object analysis according to the invention finds, for example, an application in the field of the application of standardized tests for monitoring an industrial process, for example the alteration of treatments (sulphidation, oxidation), applied in an aqueous medium. Thus, a plurality of control tanks comprising a control mirror, making it possible to check the deterioration of a treatment at regular intervals, are presented on a treadmill, each control tray being positioned at the planned analysis location, at a given moment. chosen time. Advantageously, the device of the invention allows a shooting allowing a subsequent image processing, allowing an automatic inspection of the observed deteriorations. Shooting is always done with a unique adjustment of the camera.

Advantageously, the device of the invention allows a shooting independent of the illumination of the environment, with good reproducibility of colors, intensity of illumination and uniformity of illumination.

Advantageously, it is sufficient to position the control tanks on a suitable carpet to serialize the analysis tests, without having to interrupt or disrupt the chemical reactions.

Advantageously, a strong contrast image of the chemical reactions is obtained on a highly specular surface.

In addition, the invention is also applicable for the analysis of the reflective and / or transparent surface of various supports, and makes it possible to obtain representative images of the analyzed surface with a sufficient contrast to characterize any variation on this surface. illumination of the surface being uniform in the field of view of observation, without return of stray light at least first order. Thus, it finds applications in any field requiring capture of an image representative of an object having a reflective surface.

Claims

1. - Lighting device for object analysis having at least one polished surface (S) reflecting and / or transparent, characterized in that it comprises:

at least one light source (10, 18, 32, 42) capable of illuminating the object (E) to be analyzed according to a predetermined illumination angle when the object is positioned at a predetermined location, said polished surface being positioned to be orthogonal to a viewing direction (A), and within an object view field of view, and

at least one absorber (14, 16, 34, 36) of reflective or diffusing type, said absorber (14, 16, 34, 36) being positioned with respect to said light source (10, 18, 32, 42) in such a way that light rays from said source (10, 18, 32, 42), which do not reach said polished surface (S) or which are reflected by said polished surface (S), are picked up by said absorber.

2. - Device according to claim 1, characterized in that it comprises a first source (10) of point light, positioned outside the field of view, inclined with respect to a direction perpendicular to the direction of sight (A ) at a first angle of inclination (a) so as to substantially uniformly illuminate said polished surface of the object to be analyzed.

3. - Device according to claim 2, wherein said first source (10) of light has an emission axis (B), characterized in that it comprises a lens (12) positioned perpendicular to the axis of emission (B) the first source (10) of light.

4. - Device according to one of claims 2 or 3, characterized in that it comprises a first absorber (14) of reflective type, positioned at a second angle of inclination relative to the direction perpendicular to the direction of view (A) to capture all light rays from the first light source (10) and to reflect a portion of the incident rays of light out of the field of view.

5. - Device according to one of claims 2 to 4, characterized in that it comprises a second absorber (16) of reflective type, positioned at a third angle of inclination relative to the direction perpendicular to the direction of view (A), in order to capture all the light rays reflected by the object to be analyzed and to reflect a part of the rays of light incident on said second absorber outside the field of view of observation.

6.- Device according to any one of claims 1 to 5, characterized in that it comprises a second source (18) of light, capable of illuminating substantially perpendicular to the direction of sight (A), and a semi-circular blade. an inclined transparent lens (22) positioned to capture a beam of light rays emitted by the second light source (18) and to reflect a portion of the incident light rays toward the surface (S) of the object.

7. - Device according to any one of claims 1 to 6, characterized in that it comprises a third source (32) of light, said third source (32) being positioned to illuminate the object to be analyzed in transmission in the aiming direction (A).

8. - Device according to any one of claims 1 to 7, characterized in that it comprises a fourth source (42) of light, positioned outside the field of view of observation, and able to illuminate the object to be analyzed according to a predetermined inclination.

9. - Device according to any one of claims 1 to 8, characterized in that it comprises a housing (6) with internal walls (6a, 6b, 6c, 6d, 6e, 6f) covered by a uniform matte coating , comprising an opening (8) in a first wall (6a), said opening (8) corresponding to the field of view of observation.

10. - Device according to claim 9, characterized in that the or each inner wall of the housing is adapted to absorb a first percentage of incident light and to diffuse a second percentage of incident light on said wall, the second percentage being at least ten times smaller than the first percentage.

1 1. - Device according to one of claims 9 or 10, characterized in that said housing (6) comprises lateral openings, for successively positioning a plurality of objects to be analyzed in said housing at said predetermined position.

12.- Device according to one of claims 9 or 10, characterized in that said housing (6) is of parallelepipedal shape and that two side walls located vis-a-vis with respect to each other are absent of said housing.

13.- illumination system for object analysis having at least one reflective polished surface and / or transparent, characterized in that it comprises lighting device (2, 20, 30, 40, 60) according to the one of claims 1 to 12 and a camera (4) whose lens is positioned in said viewing direction (A), the camera's field of view being said field of view, photographic apparatus being able to capture at least one representative image of said polished surface of the object to be analyzed.

14.- Use of a lighting system according to claim 13 in a method of automated inspection of a polished reflective surface and / or transparent object.