FR2585204A1 - Optico-mechanical scanning device - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS A DEVICE FOR OPTICO-MECHANICAL SCANNING OF A FIELD OF VIEW IN TWO PERPENDICULAR DIRECTIONS THAT CAN BE REALIZED ONLY BY MEANS OF MIRRORS AND THEREFORE USABLE, THEN WHATEVER THE WAVELENGTH OF THE RADIATION. THE LINE SCAN IS PERFORMED BY MEANS OF A DRUM ROTATING AROUND A FIXED AXIS EQUIPPED WITH REFLECTING FLAT FACES AND A FIXED OPTICAL ENSURING THE TRANSPORT OF IMAGES FROM THE DETECTOR TO A POINT OF THE said AXIS. FRAME SCAN IS PROVIDED BY MEANS OF A MOBILE PLAN MIRROR AROUND AN AXIS PARALLEL TO THE DIRECTION OF LINE SCAN. A FIELD MIRROR ENSURES THE FALLING OF THE BEAM FROM THE LENS AND THE FRAME SCAN DEVICE TOWARDS THE LINE SCAN SYSTEM AND THE DETECTOR. IT ALLOWS EXACT FOCUSING OF THE FIELD WITH THE ANALYZED LINE SURFACE. THE DEVICE MAY INCLUDE A SYSTEM FOR DIRECT VIEWING OF THE FIELD IMAGE USING ALL OR PART OF THE SCAN OPTICAL AND A LIGHT DIODE CONTROLLED BY THE VIDEO SIGNAL. APPLICATION: TELEVISION.

Description

The invention relates to an optical scanning device

  a field of vision divided into different areas and visualization

  said field. It relates more particularly to a

  tif operating a scanning of the field along two directions according to beams from said different zones and which converge on a radiation-sensitive element contained in said beams,

  the scanner being optically designed to be used

  whatever the wavelength of the radiation.

  Devices of this type are used in particular in

  landscape visualization devices perceived according to a radiation-

  infra-red wavelength greater than one micron (1 m).

  Such a device in which the objective is constituted by a half

  spherical pattern and the sweeping is done only by means of

  roirs, has been described in French Patent No. 1,494,805. This disc

  known positive has the advantage of being usable with a large field of vision which, at the limit, could be 180. However, it is hardly suitable for analyzing a small field with

  high resolution, which is when it comes to

  detect and recognize distant objects in the field of view and viewed at a reduced angle. It is then necessary in fact to - capture in sufficient quantity of the radiation flux emitted by these distant objects. This flux is a function of the surface of the entrance pupil of the device and in reality, in this patent, the radius of the analysis circle and the numerical aperture of the convergence optics because the focal length of the objective is, in principle, equal to said radius of analysis. '

  A possibility to increase the amount of flur cap

  it would be to increase the aperture of the convergent optics of beams on the detector; but as this is repeated several copies arranged next to one another around one of the rotation axes of the scanning system, the number

  copies would be lower which would lead to an increase in

  the speed of rotation of said optical conver-

  for the same scan rate and would pose problems

  Mechanical realization difficult to solve. Another possibility

  would consist in increasing, according to a homothety, all the

  mensions of the device. The clutter could then be

  too important as the moment of inertia of the tour-

nante.

2 2585204

  In the French patent application N 73 28 824, de-

  August 7, 1973 in the name of the plaintiff, it is

  mediates some of the aforementioned drawbacks. To make sure

  that the diameter of the entrance pupil of the device is

  male and that the field of analysis is small, one realizes a system in which the focal distance is not linked to the radius of the circle

  analysis. To do this, we introduce into the focal plane the ob-

  an optical element-lens or mirror, as the case may be, -which

  optically conjugates the center of the exit pupil of the objective

  tif and the detector placed at the center of rotation of the

  lysis, said element having the advantage of correcting the curvature

  field of the objective-device analysis set.

  In the device according to this patent application, the

  sweeping of the field in one of the directions is done by

  the mirror lens around one of its diameters.

  One of the difficulties to solve when this lens has a large diameter for opening questions, is to oscillate a heavy objective at a frequency which, for television images,

  is of the order of 20 periods per second. In addition, this objective

  even if it is parabolic, has a limited field, by

  different aberrations, to a few degrees.

  In addition, the field of view of the detector must be sufficient

  wide enough to accept the flow through the optics

  rotating during the rotation of these. As a result, the detection

  sees the inside of the analysis device supporting the op-

  most of the time, as a result of rubbing

  at a temperature higher than that of the landscape analyzed.

  It follows, in the case of an infrared analysis, the

  a parasitic modulation of the flux falling on the detector

in phase with the line scan.

  Moreover, the image of the field is not in a

  open position, the installation of a detector and a diode elec-

  troluminescent in the visible for a di-

  the image of the field, using the reverse path of the

  system of analysis, is hardly possible.

  On the other hand in this patent application optics

  not consisting solely of mirrors, this visualization

  tion is only possible if this approach is transparent in

  visible light which is difficult to achieve when

  lysis takes place in the far infrared (10 pm).

  The device according to the present invention does not

  not the same disadvantages. For reasons of practical use

  it is structured so that, while having a large compactness limiting its size, the objective on the one hand, the detector on the other hand, are separately accessible for multiple uses or for the purpose of to change their nature according to the applications while the system of analysis being carried out in two directions remains immutable, adapts to all kinds of objectives and detectors and can include only

mirrors.

  The structure of the device according to the invention allows

  thus the establishment of a detector and a light-emitting diode

  te for a direct view of the field image. From

  In order to avoid parasitic modulation due to rotating parts other than optics, the line scanning optics is made in two parts, namely a rotating drum having a large number of reflecting flat surfaces, said drum being rotated about a plane. fixed axis, and a single fixed convergence optics ensuring the concentration of the flux on the detector; said convergence optics forms an image of the detector on

  the axis of rotation of the drum which is working in convergent

  gent. To make sure to have an exact focus in the whole field in the direction of line analysis and consequently a constant resolution on all the line of analysis, a concave mirror, said of field, optically conjugates the focal surface of the objective with the analyzed line surface. According to the invention this optical conjugation is ensured by the fact that, on the one hand, the objective has a curved focal surface whose center of

  curvature is located at the center of the exit pupil of the objective

  tif and that, on the other hand, the so-called field mirror has the apex of its surface placed near the apex of the focal surface of

  the objective or more precisely of the symmetrical of said vertex by

  port to the axis of rotation of the drum and optically conjugates the

  center of the exit pupil of the objective with a point

  of the axis of rotation of the drum, the beams lying

  directed on the convergence optics of line scanning after re-

  bending on the faces of said drum.

  When large-diameter lenses are used, in order to avoid having to oscillate in a second direction for the weft-scanning of very heavy masses, the scanning in this second direction is carried out by means of a mirror plan

  mobile, said frame analysis mirror, about a perpendicular axis

  the axis of rotation of the drum, said mirror being generally

  placed in a convergent beam near the focus of the ob-

  between the objective and its focus.

  The oscillation of the convergent beam frame scan mirror reveals an additional field curvature in the weft sweep direction. This, according to the invention, is

  compensated by a small movement of alternative translation of the

  say field, synchronous with the movement of the mirror of analysis

  frame, said translation being perpendicular to the rotational axis

drum.

  In addition, to compensate for the deviation

  introduced into the line analysis system by the mirror of

  wipe sweep and ensure the fixity of the conjugate, on the axis of rotation.

  line scan, from the center of the exit pupil of the lens through the field mirror, the latter is animated by more than one reciprocating rotational movement, synchronous with the movement of the weft mirror around a parallel axis to the axis of rotation of said weft mirror and such that the average radius of any beam from the

  the field keeps a constant influence on the axis of rotation of the

  line drawing according to the frame scan.

  According to the present invention it is developed a

  positive optical scanning of a field of vision divided into different

  zones and of visualization of said field, according to the device

  which said scanning is carried out in two directions

  diculaires namely, in a direction x a scan called

  line and in another direction there is a sweep called

  weaving frame or image, device operating said scans in beams from different areas of the field and ensuring the

  convergence of said beams on a radiation-sensitive element

  contained in the said beams, a device comprising gen-

  in order, depending on the direction of the beam path

  median coordinate from the field of view, an objective, means of scanning frame in the direction y, a system of folding of the beams delimited by the opening of the lens towards line scanning means of the image field of the lens according to the direction x and the sensing element, said line scanning means, the sensing element, possibly other elements in relation to those previously mentioned for the direct visualization of the image of the analyzed field, said device being characterized in that: - the objective has its optical axis included in a plane P containing the direction y and perpendicular to x, in that said lens is interchangeable and that its focal surface is curved

  and such that its center of curvature is at the center of the

looting of the lens,

  the frame scanning means consist of a half

  plane rotating alternately around a parallel axis.

  in the x-direction, placed in a convergent bundle behind the ob-

  next to the image of the field in said objective, - the line scanning means consist on the one hand of a drum in uniform rotation around a fixed axis YY 'contained in said plane P and carrying a large number of flat reflective surfaces regularly distributed around the periphery of said drum, and secondly an image transport system

  symmetrical with respect to said plane P, forming an image of the element

  sensitively at a fixed point A 'of the drum rotation axis YY', said drum being placed in a converging beam in the

  path of said transport system on the image side of the sensing element

  sible, the symmetrical said point A 'with respect to each face of the drum when said face is perpendicular to the plane P being

  in the vicinity of the symmetrical point D of the focal point of the lens

  port to the frame mirror in a position parallel to the axis YY ', the optical system for folding the beams consists of a mirror oCrave ditdechap admitting plan. P; as a plane of symmetry and whose vertex is placed in the vicinity of D on the axis ZZ 'passing through D and perpendicular to YY', said mirror being determined so that it combines the center 0 of the exit pupil of the 'objective with a fixed point 0' of the YY axis. ' said point 0 'being symmetrical with respect to ZZ' of the point

  intersection of the optical axis of the objective with the axis YY ', the

  said field mirror to possibly ensure the nullity of the dead time of scanning between two consecutive lines, having at

  plus a width in the x-direction slightly lower than the length

  of the analyzed line itself equal to the distance between

  detector images in two consecutive faces of the drum tower

  said mirror being animated or not with a movement of small amplitude in phase with the movement of the weft scanning means,

  said small movement comprising on the one hand a translation

  ternative along the ZZ 'axis in the vicinity of D and an alternating rotation

  native around an axis parallel to the direction x symmetrical with respect to ZZ ', the amplitude of said translation being such that it corrects the defocusing introduced by the scanning means, frame, the amplitude of said rotation being such that it ensures the fixity in 0 'of the conjugate by the field mirror of the center 0 of the exit pupil of the lens during the rotation

  alternative frame scanning means.

  The invention will be better understood by means of the description

  following of some embodiments of the invention given by way of example, accompanied by figures which represent: FIG. Fig. Fig. Fig. Fig. Fig. Fig. Fig. 1 - a first embodiment of the device according to the invention. 2 - a view of the line analysis device comprising only mirrors, in section along a plane passing through

its axis of rotation.

  3 - a view of the same line analysis device in projec-

  on a plane perpendicular to the axis.

  4 - a view of the line analysis device comprising

  lenses, in section according to its plane of symmetry.

  a view of the same device in projection on a plane

  perpendicular to its plane of symmetry.

  6 - a figure explaining the role of the mirror called field.

  7 - the projection of FIG. 6 on a perpendicular plane

  to the axis of rotation of the analysis device

Reign.

  8 - a figure explaining the movement of the mirror of

lyse weft (or image).

  9 - the movement of the field mirror.

  Fi &. Fig. A second embodiment of the device according to

  the invention comprising only mirrors.

  Fig. A third embodiment of the device according to

  the invention, in section along its plane of symmetry.

  Fig. 12 - a view of said third embodiment in projection on a plane perpendicular to its plane of symmetry. Fig. 13 - an embodiment with a first system of

direct visualization of the image.

  Fig. 14 - an embodiment with a second system of vi-

direct sualisation.

  Fig. An element of the invention allowing a two-way vision

colored.

  Fig. 16 L a folded view on the plane of the sheet of the

151 of the previous figure.

  Fig. An embodiment of the invention for imaging

thermal with pyrometry.

  Fig. 18 - a provision said in parallel of the detectors of the

device according to the invention.

  Fig. 19 - a so-called series provision of the detectors of the dis-

positive according to the invention.

  Fig. A so-called series-parallel arrangement of the detections

  devices of the device according to the invention.

  FIG. 1 diagrammatically represents the

  vention according to an embodiment in section along the plane P symmetry of the device. Under number 11 is indicated a fixed lens whose optical axis is 12 and focus P. This optical axis intersects the axis YY 'at point E. The axis YY' is the axis of rotation of a system comprising a driving device 13 and a drum

  13 'laterally bearing a large number of reflective faces.

  As indicated later, this drum can have many forms. For simplicity it is assumed here prismatic his faces

  reflective being regularly distributed around the axis YY '.

  One of its faces is represented at 17 in a perpendicular position

  The planar mirror 14 is movable about an axis perpendicular to the sheet and passing through E. In fact, according to the invention, this axis does not necessarily pass through E.

  arrangement shown in Figure 1 is only preferred

  in the case where the device, as indicated below, is provided with additional means to obtain the direct visualization of the field using light-emitting diodes. Said mirror 14 reflects any beam coming from an area of the field and, passing through the lens 11, towards the mirror 16 where it forms said field

  an image located substantially on the latter mirror. On the

  1, the particular beam 15 indicated is the one with a mean radius that coincides with the optical axis 12, the image coming from

  at the point D on the ZZ axis 'perpendicular to YY', corresponding to

laying in the center of the field.

  The mirror 14 ensures the scanning of the field following the -

  y direction perpendicular to the axis 12 and contained in the plane of the figure. Subsequently, it will be called image analysis mirror or

  further analysis or even frame analysis.

  The system further comprises another fixed concave mirror 18 whose reflective surface is of revolution about the axis YY '. Said mirror forms the detector 19 placed at the point

  A of the axis YY 'an image in A' located on the same axis and symmetrical

  of D with respect to face 17.

  The system constituted by the rotating drum 13 ', the mirror 18 and the detector 19 allows during the rotation of said

  drum analysis, line by line, following the direction x

  pendicular to the plane of the sheet of the image of the field given by the objective 11 and the image analysis mirror 14 in the vicinity of the point D. This system is subsequently called line analysis system or analysis x. The mirror 16 symmetrical with respect to the plane (ZZ ', YY') ensures the optical conjugation of the center of the exit pupil 0 of the lens Il with the fixed point 0 'of the axis YY', symmetrical of E with respect to at ZZ ', so as to ensure the convergence on the detector of any beam based on the

exit pupil of the lens 11.

  This mirror 16 in that it delimits the field

lysed is called a field mirror.

  The objective is represented in this figure as realized using lenses. According to the invention, as described below, this objective can just as easily be made from mirrors. Previously, because the invention lies not only in the assembly of which it has just been described a

9 2585204

  example, but also and above all in the choice, the

  care and the combination of the elements which compose it, those

  These are the first of the detailed descriptions that follow.

  1 - Line analysis system (x) A first embodiment of this system is shown diagrammatically in FIGS. 2 and 3 respectively in projection in the plane (ZZ ', YY') and in projection on a plane perpendicular to YY '. It includes the 13 'drum spinning around

  of the YY 'axis and carrying a large number of reflecting plane faces.

  santes and the image transport mirror 18.

  The mirror 18 transports the image of a detection

  A placed on the axis of rotation YY 'at a point A' also

on the YY axis'.

  The faces of the drum 13 'are placed in a bundle

  converge in the image transport path of the mirror 18.

  The symmetries A ", A" 2 ... A "n of A 'respectively

  relative to each of the n faces of the drum then describe arcs of circle centered on the axis of rotation YY 'and contained in planes perpendicular to the axis YY', said arcs of

  circle being the supports of the scanned lines.

  The drum according to the invention can have several configurations. It may be prismatic its faces being all parallel to the axis YY 'and equidistant from it; points A "1, A" 2, ..., A "n then describe a same circle passing through D. This is the case of Figures 2 and 3 o A" 1 and A "2 represent the symmetrical of A ' relative to two consecutive faces 21 and 22. It is the same if it is pyramidal and if the faces

  reflecting reflectors have an equal inclination on the YY axis' as

  shown in Figures 4 and 5. But the faces of the drum can

  to be of unequal inclinations; points A "2 ..., A A" n de-

  then write distinct arcs centered on the YY axis'

  and contained in planes parallel to each other and perpendicular

  to YY '. The line analysis system then sweeps from one face to the other different lines passing in the vicinity of the point D.

  For example, the image transport mirror 18 is

  YY 'axis. The section of the mirror is for example elliptical and belongs to an ellipsoid portion of fires revolution

A and A '.

  It is not obligatory, however, that the torus be

  elliptical section: the elliptical shape is only the best

  their theoretical form. In some cases, depending on the applications,

  it is possible to confuse with a good approximation the sec-

  elliptic section with another section that deviates little and which

  is easier to achieve, for example a circular section.

  According to a variant close to this embodiment, the

  torus is not only mirrors but is catadioptric.

  The scanning device then loses the advantage of operating at all wavelengths because it is no longer

  consisting only of mirrors, but then offers the advantage of -

  have new parameters for aberration correction

  In a second mode of implementation, the transport of

  The detector's imaging on the axis is performed using a lens lens. This embodiment is shown in FIGS. 4 and 5 in projection respectively on a plane containing the axis

  YY 'and on a plane perpendicular to said axis.

  The detector is located at A outside the rotational axis

  YY '. The objective 41 gives the detector an image located in A '

  on the axis of rotation YY '. The drum 13 'can still be taken

  regular or irregular pyramidal or pyramidal around YY '. The Sy-

  metric A "of A 'with respect to one of the faces 42 of this drum further describes a circular arc 43 centered on the axis YY' and passing through D or in its vicinity, identical or not to itself; a face

  to each other as appropriate, as already indicated above.

  This system has the disadvantage of not being of revolution around the axis YY ', so that the image A' or A "is not

  no consistent quality depending on drum rotation.

  Moreover, the objective 41 must have a very large opening

  which is a function of the length of the line analyzed.

  This second embodiment which is part of the

  vention may be useful in some applications. But it is generally preferred to the system toroidal mirror for the benefits it has, said advantages being as follows:

  - use at all wavelengths of the light

  Mière. checks and adjustments of possible

  visible because the system is entirely mirrored.

* So greater ease of construction.

11 2585204

  image of constant quality given by the torus whatever the angle of rotation of the drum, because the axis YY '

  is an axis of symmetry of the line analysis device.

  On the horizontal projection of the line scanning system of FIG. 3, 21 and 22 represent two consecutive reflecting faces of the drum 13 '. 33 and 34 are the normals on each of these faces (or the projections of these two normals on

  a plane perpendicular to the axis YY 'when the drum is pyra-

  Midal). These normals make an angle o.

  A "1 and A" 2 are the symmetries of the image A 'of the

1 2

  A, respectively, with respect to the faces 21 and 22. The angle of the mirror 21 or 22 from A 'is also i. This angle o sets the maximum length of the analyzed line carried by the arc

  of circle A "1 A" 2 during the rotation of the drum 13 'and the

  the mirror 18 must be present. Indeed, the detector must not simultaneously receive flux coming from two

  different points of the line. The line analyzed must not

  contain only one image of the detector; assuming that the drum 13 'rotates in the direction of the arrow 35 and that the mirror

  If he started scanning the line at A "1, he must

  to finish it in A "2 when the mirror 21 starts on

  scan of the next line in A "1. The opening of the mirror to-

  must be sufficient in the plane perpendicular to YY 'so that the rays coming from A "1 or A" 2 are reflected towards A.

  deduced from this, as it can be seen directly from the

  3, that this opening must be greater than or equal to 2 o

(2).

  Thus conceived, the dead time between sweeps of two

consecutive lines is zero.

  The length of the analyzed line is determined by the number of facets of the rotating drum which fixes the angle (, therefore

the length A "1 A" 2 of FIG.

  Furthermore, the so-called field mirror 16 of FIG. 1 intervenes to prevent the flow that falls on the detector from coming from several points of line A "1 A" 2 of FIG.

as indicated below.

2 - Mirror of field

  The roles and configuration of the field mirror (half

  16 in FIG. 1) are explained using FIGS. 6 and 7. In FIG. 6, the input optics is represented in projection on the plane of symmetry of the device passing through the axis YY '. The image analysis mirror was omitted so as not to overload the

  figure, and because of this absence, the objective

  in a symmetrical position with respect to the axis YY 'of his v

  real position, which in no way restricts what is said in

  what follows. This is the name of the center of the pupil of

  of the objective placed in said symmetrical position.

  In addition, several straight sections of surface are represented, namely: under the number 61 the cross-section

  of the field mirror, under the number 62 the cross section of the sur-

  focal face of the objective 11l of center O ", under the number 63 the cross-section of the analyzed surface of center O 'located on

  the axis YY 'and intersection of a radius OG reflected in G on the

  right section 61 of the mirror 16. These straight sections intersect at a point D located on the optical axis of the lens II and corresponding

in the center of the field.

  This field mirror 16 has several roles. It is designed to reflect any ray from O "such that 0" G into a radius such that O'G passing through the fixed point O 'of the axis YY', said point O 'being asymmetrical of E intersection of the optical axis with YY '. A first role is thus to conjugate the center O "of the exit pupil of the objective 11, so O in reality, with the

  fixed point O 'of the axis of rotation, a condition for any

  from one of the fields of the field associated with any ray passing through O and taken up by the line analysis mirrors.

  converge on the detector placed at A on the axis of rotation YY '.

  The introduction of such a mirror has a priori the disadvantage of introducing its own field curvature. In fact, it is not so, and thus appears a second role played by the mirror of

  field: according to the invention, its curvature is used to correct

  the effects of aberrations due to the curvature of the objective 11 and that of the line analysis system. It gives the focal surface

  of Objective 11 (section 62), an image coinciding with the

  analyzed face (of section 63) centered on O ', which is obtained because the focal surface (of section 62) is centered on the

  exit pupil of the objective he and that the field mirror con-

  optically judged 0 "(hence 0) and 0 '.

  In its most theoretical form, this field mirror is

  a portion of ellipsoid of revolution of foci 0 "and 0 'and

  holding the point D and any point such as G. In practice and according to the invention, use will be made of a shape close to the ellipside and easier to obtain which is a portion of sphere passing through D and centered on the point C located at the intersection of 0 "0 'with the axis ZZ', perpendicular to YY 'and passing through D. Its radius of curvature is such that inproject on the plane perpendicular to YY' at D, said mirror as indicated in Figure 7 conjugates H and H 'projections respectively of 0 "and 0'

on said plane.

  The analyzed line is the arc of circle 73 of center H ', intersection of said plane with the sphere of center 0' and radius

  O'D, while the straight sections of the focal surface of the ob-

  jectif Il and said mirror are the arcs respectively

72 and 71.

  According to the invention, the field mirror 16 can be limited

  in the plane perpendicular to YY 'and containing ZZ' to an infinitely small arc in the direction YY 'of center H',

  circle giving a point B of 72 corresponding to the radius of pro-

  jection HB an image B 'on the arc 73.

  In some cases, the arc is comparable to the tangent surface. According to the invention, the field mirror 16 is

  then in particular a cylindrical mirror whose axis is parallel

  is linked to YY 'and goes through C. A third role played by the field mirror is to fix the dimensions of the analyzed field including the length of the line whose maximum value is determined, as already seen, by the number of facets of the drum. rotating, and corresponds to the arc A "A" 2 centered on A ', represented in FIG. 3, A "1 and A" 2 being the images of the detector given by the line analysis system,

  using two consecutive faces of the drum 13 '.

  The field mirror 16 has a width smaller than the arc A "1 A" 2 so that the flux that falls at A on the detector

  come only from one point and one from the line.

  One of the edges of the mirror may for example coincide with A "2 while it will be slightly set back relative to A"

as shown in Figure 3.

  For reasons of constancy of image quality of the field as a function of the direction of the analyzed field in direction y and also for congestion issues of the line analysis system, it is desirable that this analysis system line is crossed by the rays with the same incidence whatever

this direction.

  The invention ensures this condition by animating the

  field of a synchronous reciprocating motion of the image analysis mirror. These movements are described in what

  follows during the description of the image analysis system.

3 - Image analysis system.

  This system is shown schematically in Figure 8 in section in the plane ZZ ', YY'. The image analysis mirror 14 is

  alternately rotated about an axis

  pendicular to the plane of the figure passing through point E located on

  the optical axis of the objective 11. E is represented on the axis of rotation

  YY 'analysis drum x. E can actually occupy a

  other position. In order to reduce the dimensions of this mirror and

  put a high frequency of oscillation, it is generously placed

  very close to the focal area of the lens 11 section

  62. This provision also has the advantage of permitting

  put the use of short focal length lens and

reduced optical print.

  As in Figures 6 and 7, D represents the image of the detector A by the line analysis system for the center of the field. The OE ray coincident with the optical axis passes through D

  after reflection by the mirror 14, when it occupies the posi-

  analysis of the center of the field that is to say makes a zero angle c

with YY '.

  During the rotation of the mirror 14, the symmetry of D with respect to this mirror describes the arc 81 of center E and radius ED1, D1 being the symmetry of D with respect to YY '. For the direction 82 of the field making with the optical axis 12 the angle (measurement from the center O of the exit pupil of the objective,

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  represented in FIG. 8 as coinciding with the objective 11, and corresponding to a position of the plane of the mirror 14 making the angle c with YY ', the image of the detector is at D3 on the arc 81, while the image of the field in the direction -3 is in D'3 on the section 62 of the focal surface, or, after reflection on the mirror 14, D "symmetrical of D 'with respect to the plane of the mirror 14. It appears as well as if the image of the detector by the

  mirror 14 in the position parallel to YY 'is of course on the

  focal face of the lens 11, said image deviates from it as a function of the angle of view P, a defocus appearing according to the

  segment D3D'3, or DD "of length 1.

  The theory shows that DD "makes an angle with ZZ" of

  their = - 2 while the value of 1 is given by the relation

tion:

1 = - LM +

  sin 2d, with L r S sin M = cos (+ i - +) a = L2 (M2 1) + R2 "= 2 [" + arsin [(R _ 1) + sinpM

R = OD1

r = ED

  o i represents the angle of ED with ZZ '.

  According to the invention this defocusing is corrected by printing to the field mirror 16 the movements of small amplitude suitable for the tangent to the top of said mirror to be at all

  moment the mediator of DD. "These movements are decomposing:

  firstly an alternative translation movement of amplitude I

  cos X in the direction ZZ 'from Z' to Z, secondly a rotation

  2 alternation of amplitude around an axis parallel to x and symmetrical with respect to ZZ ', said translation and rotation

  being in phase with the movement of the frame mirror 14.

  The position of the mirror 16 is indicated in FIG. 8 for the angle of field λ, by means of the tangent 83 to said mirror at its apex, initially perpendicular to ZZ 'at D for the center of the field, that is to say for o and (zero) This tangent is - 1 distant from D in the direction of DD "while making an angle with YY 'equal O-- 2-, so that the radius OD'3

2 3

  crosses the axis ZZ 'in D after successive reflections on the mirror 14 and the mirror 16, and passes through the conjugate point O' of O by the

  mirror 16 in its initial position.

  Whatever δ, D is thus the image of D "in the field mirror and the average radius of the beam, after reflection on said mirror, has a constant inclination i on the axis ZZ '

  so that the center O of the exit pupil is

  conjugate with the same fixed point 0 'of YY'.

  It follows that for any direction of angle P of the field the focal image of the lens II in the field mirror is

  still be confused with the surface analyzed by the

positive line analysis.

  The complex motion of the field mirror is obtained,

  for example, as shown in Figure 9. The mirror 16 is

  perpendicularly to a rectilinear support AB such that A translates on the axis ZZ 'while B describes the arc 91 centered on ZZ' and contained in the plane (ZZ ', YY'). In FIG. 9, M represents the position of the mirror passing through D corresponding to the center of the field and M 'the position of the mirror for the angle field direction (the support then occupying the position A'B' has turned from angle - + with respect to AB in the sense of the

arrow 92.

  Such compensation of the defocusing, brought by the image analysis mirror 14, makes it possible to obtain a resolution limit that is as good in the whole of the scanned-x-field and

  y than in the center of the field. Moreover, the resolution limit

  born by the objective is not impaired by the system of analysis in

x and y.

  Now described as an example

  two other embodiments of the opticomechanical scanning device o come in combination the elements that have

17 2585204

  have been described in detail previously.

  One of the achievements is shown in Figure 10

  following the plane of symmetry of the system.

  It has the particularity of being realized completely-

  from mirrors. The entry objective is constituted by the reflecting mirror 101 pierced with an orifice 102 and a mirror, like a telescope mirror 103 with a parabolic section. The optical axis of the objective is represented under the number 104. The focus is located at F. The beam from a point to infinity after returning by the fixed mirror 101 and the mirror 103 passes through the orifice 102 ., then it is then supported by the analysis system itself, namely the image analysis mirror 14, the field mirror 16, the rotating drum 13 'and the image transport mirror 18 for

  come converge on the detector 19.

  In FIG. 10, the beam 105 represented is that

  which admits for mean radius that coincides with the optical axis 104.

  Given the telescope mirror 103 used, the field is

the order of 0.5 to 3 for example.

  The other embodiment is shown in FIGS.

  11 and 12 respectively in section in the plane of symmetry of the dis-

  positive and in projection on a plane perpendicular to the axis YY '

  rotation of the line analysis system.

  This embodiment has the particularity of using

  the image analysis mirror 14 placed, upstream of the objective, in a parallel beam, said mirror being movable about an axis perpendicular to the plane of FIG. 11 and passing through the point E

  of the axis YY 'on which is placed in A the detector.

  The mirror 14 delimits the beam that enters the

  system and can be considered as the entrance pupil of the system.

  analysis which has a symmetry of revolution around the YY 'axis and, as a result, identical optical properties in

all directions of the field.

  The objective used is a toroidal mirror 114 of axis YY 'and sectioned by any plane passing through YY', parabolic. The focus of the section by the plane of the sheet is at the point D center of the field on the axis ZZ 'passing through A', image of the detector by the mirror scan ring line 18. The focal length of the

  mirror 114 is chosen to be equal to the radius of the circle of

  lysis such that A'D = DS, S being the vertex of the torus section, said vertex being located on ZZ '. The toric mirror 114

  is limited to its area above the ZZ 'axis.

  The place of the foci such that D is a circle 121 of radius A'D in the plane perpendicular to YY 'passing through D. These foci are successively merged with the image,

  in the line analysis system, the detector.

  The arc described by this image is limited to the points A "and A" 2 corresponding to the images of the detector respectively in

  two successive faces of the rotating drum 13 '.

  In this system the mean radius of the ray bundle

  analyzed followers always passes, after reflection on the mirrors

  14 and 114, by a point of the arc A "1A" 2 which are themselves

  even the conjugates of the detector A by the line analysis system.

  The lens 114 thus acts, in a way, as a field mirror in connection with the fact that the axis YY 'is an axis

  of symmetry for the whole optical system.

  So that the detector does not receive flux from two points of space at the same time, the field is limited by a diaphragm

125 outside A "1A" 2.

  The analyzed field is then equal to the angle o from which is seen from D a face of the drum (Fig. 12), that is to say from the order

  for example from 20 to 60 depending on the number of facets of the drum.

  The device has been described according to some modes of

  particularization, where the analyzed field is at infinity.

  It goes without saying that the invention is not limited to these cases and that the field can very well be at finite distance. Systems

  line and frame scanning are in fact compatible with the

  the use of all kinds of small and large objectives aimed at finite or infinite distance, such as, for example,

  microscope or zoom lenses, the resolu-

  obtained by being always very large because of the perfect

  calibration of the detector image on the image surface of the ob-

  jective. Resolution can reach the limit due to diffraction

  in the entire field of the device.

  It should also be noted that the invention easily leads to

  compact units, but whose compactness leads no less, thanks to the obliquity of the beams on the field mirror and on the line scanning elements, to a structure o

  the detector is in a position outside the system.

  the actual optico-mechanical analysis system.

  In addition to the optico-mechanical analysis device which has just been described in detail, the invention comprises devices allowing the direct visualization of the objects analyzed or the application of this device to the infrared imaging of

  certain objects or in other wavelength domains.

  For said direct visualization, the video signal is

  of the detector is applied after amplification suitable for

  electroluminescent diode in the visible spectrum, whose lumines-

  it is proportional to the signal it receives.

  The analysis system in its version comprising only

  mirrors, can be used indifferently for all

  wavelengths. The direct vision of the analyzed object is thus made possible by using the same system for analysis and restitution.

  A first embodiment of the invention relates to

  this visualization is shown as an example in the

  Figure 13. The analysis and visualization beams respectively

  15 and 131 use different symmetrical paths

report to a plane containing YY '.

  The analysis device is that described in FIG.

  The display device comprises a field mirror 132 symmetrical with respect to YY 'of the mirror 16. The mirror 132 is not necessarily mobile because the viewing beam may have a smaller aperture than the analysis and that the eye can easily accommodate to compensate for a small field curvature. The image analysis mirror 14 is reflecting on its

  two faces, one of the faces for analysis, the other for

  sualisation. The mirror 134 is arranged in such a way that the

  metric of the light-emitting diode 133 is confused with the detector 19. The amplification chain 140 amplifies the signal

  video from the detector 19 and applies it to the diode 133.

  The image of the analyzed field restored by said electrolysis diode

  minescente and the analysis system is observed using the eye

  137 behind the magnifying glass represented schematically

  by optical elements 135 and 136 or directly

behind the collimator 139.

  The bezel has the advantage of straightening the image. It can be added an intensifier tube 138 to increase the luminance of the image and provide a time constant by the

  lack of screen making viewing more enjoyable.

  A second embodiment of the invention for this

  visualization is shown in Figure 14.

  In this embodiment, which is particularly suited to imaging in a restricted domain of the spectrum, the analysis and visualization beams, respectively 15 and 141, use largely common paths thanks to the dichroic mirrors 142 and 143. These mirrors have the property of being let through the light of the spectrum of analysis, while they reflect

  the rest of the spectrum. The mirror 142 is arranged in such a way that

  that the symmetry of the light-emitting diode 144 in this

  mirror is confused with the detector 19. The video signal in

  detector 19 is amplified by the amplification chain

  towards the diode 144. The mirrors 142 and 143 reflect

  to the telescope, optical elements 135 and 136, and the eye 137 the light emitted by the light-emitting diode 144

  and not included in the analysis spectrum.

  When the analysis is carried out in the infrared, the two mirrors 142 and 143 are advantageously each constituted by a germanium plate allowing the infrared to pass and reflecting the

  visible beam from the light emitting diode 144.

  Another type of visualization of the field image is

  whoever uses a CRT on which the signal is sent

  video signal provided by the detector, the line and frame sweeps of said cathode ray tube being synchronized with the line sweeps

  and weft of the optico-mechanical device.

  When the input objective (11 in FIG. 1) is a mirror lens, the device of the invention comprises only mirrors. It is then usable for imaging at all wavelengths. It can enable "bicolor" imagery

  or 'hulticolor' and be used both in the ultraviolet spectrum and

  only in the visible or infrared.

  According to the invention the analysis can be simultaneous on

21 2585204

  the different colors or, to be done in sequence on each

colours.

  For the simultaneous analysis on different colors, the device comprises for example in the same vessel Dewar several detectors D1, D2 ,.

  , Dn in number n respectively responsive to the wavelengths 1'3 '' 2, Xn and arranged in a single row in the direction of line analysis. These detectors provide the sequence of signals S1, S2,..., Sn out of phase with each other. These signals are re-phased by means of delay lines. The images at wavelengths i 2 '' '' An are then..DTD: exactly superimposable. By appropriate electronic processing

  In the known art, it is then possible to reveal the difference between images at different wavelengths by sums or signal differences, for example (S1 + S3) - (S2 + Sn). In another embodiment of analysis

  simultaneous detection in several colors, detectors

  to different Dewar vases. For example for a "bicolor" analysis at the wavelengths X1 and> 2 'the two detectors D1

  and D2 belonging to two different Dewar vases can be

  placed symmetrically with respect to a dichroic mirror as are the detector 19 and the diode 144 in FIG. 14 with respect to the dichroic mirror 142, said dichroic mirror for example passing the wavelength> 1 and reflecting the wavelength A2 'For a sequential type color analysis, for example in two colors, an embodiment of the invention is shown in FIG. 15. Two detectors D1 and D2 respectively sensitive to the wavelengths X1 and X2 are symmetrical by

  relative to the rotating disk 151 shown with its plane perpendicular to

  to the sheet and parallel to the axis of rotation YY '. This disc

* that turns around the axis 152. The faces of the disc are

  slick and slit. In FIG. 16, there is shown

  the disc in its plane. The reflective part of the face

  parent is hatched while the slots are indicated in

  numbers 161 and 162. The rotation of the dicke is

  rotated in rotation with the image scan. During the rotation

  D1 and D2 alternately receive the flow that passes through the imaging system thus allowing analysis in "bicolor". In

22 2585204

  this embodiment the device may furthermore comprise a radiation source 153 placed so that its mean emission radius has an inclination on the disk 151 symmetrical with the mean radius of the line analysis beam coming from the mirror 18 and passes through D1 or D2. This flux source is alternately seen by D1 and D2 and serves as a flux reference for the flow coming from

of the analysis.

  The device according to the invention is particularly suitable for obtaining thermal imaging with absolute measurement of temperatures. An example of application in this field of the device according to the invention is shown in FIG.

  this figure is shown in projection in a plane perpendicular

  at YY ', scanning along a line. During this week

  the image of the detector in the analysis system describes a

  arc of circle 171 centered on the axis of rotation of the drum of

  lysis projected at H 'in Figure 17. The ends of this arc are A' and B 'respectively corresponding to points A and B of the image field located on the cross section 173 of the focal surface of the lens. It will be remembered that the sectional field mirror 172 has, in particular, the role of combining on the one hand A and A ', and on the other hand B and B'. While in A 'the detector receives the flow corresponding to the point A of the chami, it interrupts the field mirror in B' so that the detector does not receive more flux from the point B, but that of the small source 174 of reference located in place of the field mirror. As we saw earlier, the total length of the field mirror and the reference source

  should be slightly less than the length of the line of

  lysis. At the beginning or end of each line of

  nalysis of a reference signal that can be calibrated

  and can be compared with the signal given by the lens.

  The advantage of this system is that the reference source

  is seen at each line of the image. The reference signal has only a duration equivalent to a few points of analysis and

  does not disturb the field analysis. The reference source is small

  tite. This is for example a black body whose emission surface may be less than one square millimeter. It is possible to vary the temperature quickly and control it at any

  moment by usual measuring means (thermocouple for example).

xample).

  The device of the invention is compatible with the use

  detection of detectors of any kind, cooled or uncooled.

  The detection system may comprise a single detector, but it may also consist of detectors in number n, arranged parallel to each other on a column, (provision called in parallel thereafter). This arrangement is shown in Figure 18, where the small quadrilaterals are the

  detectors, and arrow 181 gives the direction and direction of the

  line drawing which is carried out perpendicularly to the column of detectors. The image of these detectors in the analysis system

  line sweeps n lines at a time from the field. On line scan

  In this case, the image analysis system shifts the scanning line by n lines, which makes it possible to lower the rotational speed of the drum.

  turning. At an equal number of lines per second, the rotational speed

  This system is n times smaller than for a single detector. This system requires the amplification of the detected signal, each of the channels being assigned to one of the detectors. The detection system can also be provided by n detectors placed one after the other

  others in the direction of the line scan (

  series later). This provision is represented on the

  figure 19o laf chel9 indicates the direction and direction of the scan.

  age. Each image of a detector in the line scanning system scans the same line and gives for each point of the line a signal shifted in time with respect to the given signal, for the same point, by the other detectors. These signals are delivered

  phase by means of delay lines in order to obtain in defini-

  the same signal delivered to a single amplification channel. All

  then happens as if using a single detector of sen-

  improved sibility in a ratio equal to \.

  It goes without saying that the detection system can still

  parallel series, that is to say, to understand, as

  20, n1 columns of detectors placed along n2 lines, the line scan being carried out according to the arrow 201. It is thus possible in this way to divide by n2 the rotational speed.

  rotating drum (13 'in the figure) with a good sensitivity

in the report.

  In the case of restitution of the image by diodes

  troluminescent, one can have an assembly of n diodes

  identical to that of the n detectors. Similarly, one can obtain di-

  rightly a color rendition by applying to diodes

  of different colors the video signals coming from sen-

  at different wavelengths.

  In the case of multicolor analysis the same arrangement in series, parallel or parallel series may be adopted

  for detectors sensitive to different wavelengths.

  The scanning device according to the invention, by its

  wide field is compatible with the usual television standards.

  high definition, for example the one said to 625 lines per image. Such a standard corresponds to scanning 625 lines 25 times per second, so in fact scanning 15.625 lines per second. The device according to the invention can then be constituted for example by a rotating drum with 12 faces and a detector with 5 elements in parallel. 60 lines (5 x 12) are analyzed per drum revolution. A rotation of the drum at the speed of 15.625 rpm ensures a line scan of the image at the same frequency as that of the television in the standard 625 lines considered.

Claims (26)

  1. Optical scanning device of a field of view di-   referred to in different zones and of visualization of said field,   in which said scanning is carried out in two direc-   perpendicular, ie in one direction x one sweep   referred to as line sweeping and following another direction there   layage referred to as frame or image scanning, device operating said scans according to beams coming from the different zones of the field   and ensuring the convergence of said beams on an element.   to the radiation contained in said beams, device generally comprising in the order, in the direction of the path of the median incident beam from the field of view, an objective, weft scanning means in the y direction, a system for folding the beams. delimited by the opening of the lens towards line scanning means of the image field of the lens   in the direction x and the sensing element, said means for   line, the sensitive element, possibly other elements   related to those mentioned above for the purpose of   directization of the image of the analyzed field, said device being characterized in that:   the objective has its optical axis included in a plane P containing   the y direction and perpendicular to x, in that the said ob-   jectif is interchangeable and that its focal surface is curved and such that its center of curvature is located in the center of the exit pupil of the objective, - the frame scanning means are constituted by a plane mirror rotating an alternating movement around a parallel axis   in direction x, placed in a convergent bundle behind the objective   near the image of the field in said objective, the line scanning means consist on the one hand of a drum in uniform rotation around a fixed axis YY 'content   in said plane P and bearing a large number of planar faces   bending regularly distributed around the perimeter of   drum, and on the other hand a symmetrical image   relative to said plane P forming an image of the sensing element at a fixed point A 'of the axis YY' of rotation of the drum, said drum being placed in a convergent beam in the path   said transport system on the image side of the sensing element.   symmetrical of said point A 'with respect to each face of the drum   when said face is perpendicular to the plane P being in the vicinity   swimming from the point D symmetrical to the focal point of the objective relative to the frame mirror in a position parallel to YY ', the optical system for folding the beams consists of a so-called concave mirror of the field admitting the plane P as a plane of symmetry and whose vertex is placed in the vicinity of D on the axis   ZZ 'passing through D and perpendicular to YY', said mirror being de-   terminated so that it couples the center 0 of the exit pupil of the objective with a fixed point 0 'of the axis YY,   point O 'being the symmetric with respect to ZZ' of the point of inter-   section of the optical axis of the lens with the axis YY ', said half   roir de champ to possibly ensure the nullity of the dead time   sweeping between two consecutive lines having not more than one   in the x-direction slightly less than the length of the analyzed line itself equal to the distance between the images of the detector in two consecutive faces of the rotating drum, said mirror being animated or not with a small amplitude movement in phase with the movement of the weft scanning means, said small movement comprising on the one hand an alternating translation along the axis ZZ 'in the vicinity of D and an alternating rotation around an axis parallel to the direction x symmetrical with respect to ZZ', the amplitude of said translation being such that it corrects the   defocusing introduced by the frame scanning means, the   plitude of said rotation being such that it ensures the fixity in O 'of the conjugate by the field mirror of the center O of the exit pupil of the objective during the alternative rotation of the means raster scan.   2. Device according to claim 1 characterized in that   that the rotating drum is a prism whose faces are   and also spaced apart from the axis YY 'or a pyramid whose faces have the same inclination with respect to YY' and that A 'and D are strictly symmetrical with respect to each of the faces successively placed perpendicular to the plane P. 3. Device according to claim i characterized in that   that the rotating drum is a pyramid whose reflective faces   are unequally inclined relative to YY '.   4. Device according to one of claims 1 to 3, characterized   in that the image transport system of the means of   layage line consists of a concave mirror toric axis YY ',   said mirror admitting as a plane of symmetry a perpendicular plane   YY 'sensing element and its image A' in said mirror being located on YY '. 5. Device according to claim 4 characterized in that the section of the toric mirror by a plane containing YY 'is an ellipse whose main axis coincides with YY' and whose   one of the homes is occupied by the sensitive element.   6. Device according to claim 5 characterized in that   that said section is practically a circle.   7. Device according to one of claims 1 to 3, characterized   characterized in that the image transport system of the line scanning means is a toroidal reflector around the axis YY ', said reflector admitting as a plane of symmetry a plane perpendicular to YY' the sensing element and its image being located on YY '.   8. Device according to one of claims i to 3 characters   in that the image transport system of the means for analyzing   lysis line is a lens lens, the sensitive element is   outside the YY axis', the focal distance from the lens to   lens being determined so that it forms the image A 'of the element   sensibly on the YY axis' to the point previously indicated by port to D.   9. Device according to one of claims i to 8 charac-   tered in that the so-called field mirror is a portion of elliptical   balance of foci 0 'and 0 ", 0" being the symmetric of 0 relative   to the weft mirror in a position parallel to YY ', said ellipside not   by D, or in the immediate vicinity of D.   10. Device according to one of claims 1 to 8, characterized   characterized in that said field mirror is a sphere portion having at its center the point C intersecting the line joining said points 0'0 "and ZZ ', said sphere passing through D, or in the immediate vicinity of D.   11. Device according to one of claims 9 and 10   characterized in that said field mirror is likened to a sur-   cylindrical face tangent to the previously indicated surfaces.   12. Device according to one of claims 1 to 11 character- 28 2585204   in that the amplitude of the translation of the field mirror   on the ZZ 'axis and that of rotation around the x direction,   read from the reference position corresponding to the case where said mirror has its vertex at D while the weft mirror is parallel to YY 'and the field angle is zero, are respectively 2 cos Y and g = - o represents the angle of the mirror 2 2   frame with YY 'and -3 the angle at which the edge of the field is seen from the center of the exit pupil of the objective, l, z and P being bound by the following relations: 1 = - LM +   sin 2o <with L = r sin 2 sin (5 M = cos (+ i -) = L2 (M2 - 1) + R2 - 2 [[ô + arc sin [(- 1) + sin]] R = OD   r = ED D1 being the symmetry of D with respect to YY 'E the intersection of the optical axis of the lens with YY' i the angle of ED with ZZ '   13. Device according to one of claims 1 to 3, characterized   in that it is carried out in accordance with all the   claims consisting of one of claims 4 to 6 and one of claims 9 to 12.   14. Device according to claim 13 characterized in that   that the lens has lenses.   15. Device according to claim 13 characterized in that   that the lens has only mirrors.   16. Device having only mirrors similar to   device according to claim 15 characterized in that the half   The raster scan is placed in a parallel beam in front of 29 2585204   the lens, its axis of rotation being perpendicular to the axis YY 'and intersecting said axis, said lens also acting as a field mirror, being constituted by a concave fixed mirror of toroidal shape around YY', of section by any plane passing through the said axis, of parabolic type, the foci of the said sections being the   of the detector by the line analysis system, said half   the field lying above the plane perpendicular to the axis YY 'and passing through the line of said foci, a field diaphragm placed on the   focal area of said mirror limiting the length of the line lysed.   17. Device according to one of claims 13 to 16   characterized in that the direct visualization system of the field image comprises optical elements that are symmetrical with respect to   line scan rotation axis of those part of the system.   analysis system and further comprises a plane mirror in which a light-emitting diode in the visible range is symmetrical   of the detector, and means for applying to said diode   luminescent the signal from the detector, said image of the field being observed with the help of the eye through or not a telescope.   18. Device according to one of claims 13 to 16,   characterized in that the optical elements of the analysis system of   image are common with the optical elements of the video system.   sualisation which includes, in addition, two flat dichroic mirrors,   namely a first dichroic mirror placed such as the diode elec-   troluminescent is symmetrical detector and a second dichroic mirror placed upstream of line and frame analysis systems,   said dichroic mirrors being transparent to the light of   lysis and reflecting electroluminescence light, the image being observed using the eye through or not a telescope.   19. Device according to one of claims 1 to 18,   characterized in that the detector as the light emitting diode   it has n elements, the elements of the detector being sen-   at different wavelengths, the elements of the diode emitting in different colors, the geometric assembly of the detector elements being identical to that of the elements of the diode, said assemblies being symmetrical to one another with respect to the mirror plan indicated in claim 17 or 18, and in that said device comprises means for applying the video signal from an element of the detector to an element of the diode, and optionally optical elements acting as light filter.   20. Device according to one of claims 1 to 18,   characterized in that it further comprises a source of reference radiation placed on the line path of the detector image   at the end of an analysis line.   21. Device according to claim 19 characterized in that the detector comprises two elements D1 and D2 sensitive each   at a wavelength range centered respectively on the   w1 and the wavelength t2 'the element D1 being   placed on the line scan rotation axis, while the   D2 is placed symmetrically at D1 with respect to a dichroic mirror, the dichroic mirror being transparent to the length   of wave X1 and reflecting the wavelength k2.   22. Device according to claim 19 characterized in that the detector comprises two elements D1 and D2 each responsive to a wavelength range centered respectively on X1 and 2 and in that the two detectors are symmetrical with respect to a rotating disk. , the disc surface being reflective on both sides and interspersed with slots, said device   possibly also having a radiation source of   emitting in an average direction of the same inclination   on the disk as the average beam of the analysis beam.   23. Device according to one of claims 1 to 18,   characterized in that the detector comprises a plurality of sen-   placed in a column perpendicular to the direction of the line scan.   24. Device according to one of claims 1 to 18,   characterized in that the detector comprises a plurality of sen-   placed one after the other in a row   parallel to the direction of the line scan.   25. Device according to one of claims 1 to 18,   characterized in that the detector comprises several columns of ele-   sensitive elements placed in several perpendicular rows 30 31 2585204   said columns which are directed perpendicular to the di- line scan rection.   26. Device according to one of claims 1 to 20 com-   carrying detectors each sensitive to a certain range of wavelengths, each of these detectors having one of the struc-   tures indicated in claims 23 to 25.