FR2586519A2 - Optico-mechanical scanning device - Google Patents

Abstract

THIS DEVICE ENSURES THE OPTICAL SCAN OF A FIELD OF VISION IN TWO PERPENDICULAR DIRECTIONS CALLED LINE AND FRAME. THE DEVICE ENSURES THE CONVERGENCE OF THE OPTICAL BEAMS FROM THE DIFFERENT ZONES OF THE FIELD ON A SENSITIVE ELEMENT. THE LINE SCAN MEANS INCLUDING A FIXED TORIC MIRROR OF REVOLUTION AROUND THE ROTATION AXIS OF THE SAID LINE SCAN MEANS FORMING AN IMAGE OF THE SENSITIVE ELEMENT ON ITS ROTATION AXIS. ACCORDING TO THE INVENTION, THIS MIRROR IS IN THE FORM OF TWO PARTS EACH BELONGING TO THE CONCAVE SURFACE OF A PARABOLOID, THE AXES AND SUMMITS OF THE TWO PARABOLOIDS BEING LOCATED ON ITS ROTATION AXIS OR RESPECTIVELY ON ITS AXIS AND ANOTHER AXIS WHICH IS PERPENDICULAR IT . APPLICATION TO NOCTURNAL VISION.

Description

The present invention is a first addition to that which is the object

  of patent application No. 75 03 923 filed on

  February 7, 1975 in the name of the plaintiff.

  It constitutes an improvement to the scanning device o-ticn a field of vision and viewing of said

  field described hnsladite patent application.

  According to this patent application, it is developed an optical scanning device of a field of vision divided into different zones and of visualization of said field, a device according to which said scanning is carried out in two directions.

  perpendicular, that is to say, in a direction x a scanning de-

  line and, in another direction, a scan

  ge denominated sweep frame or image, device operating said sweeps according to beams from different areas of the field

  and ensuring the convergence of said beams on a sensing 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 aperture of the objective towards line scanning means of the image field of the objective in the direction x and the sensitive element, said means of

  line scan, the sensitive element, possibly other

  with those mentioned above for the purpose of

  directization of the image of the analyzed field, said device being remarkable in that: the objective has its optical axis included in a plane P containing the direction y and perpendicular to x, in that said objective is interchangeable and that its focal surface is curved and such that its center of curvature is situated at the center of the exit pupil of the objective, the frame scanning means consist of a plane mirror

  rotating reciprocally around an axis parallel to.

  the 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 carrying a large number of flat faces rc-

  bending regularly distributed around the perimeter of

  drum, and. the other parent symmetrical image

  only by ramSort to Golan P forming an image of the sen-

  at a fixed point A 'of the drum rotation axis YY', said drum being placed in a convergent beam in the path of said conveying system of the image side of the sensing element, symmetrical with said point A 'with respect to each side 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 determined so that it conjugates the center O of the exit pupil of the objective with a fixed point O 'of the axis YY', said point O 'being symmetrical with respect to ZZ' of the point of intersection of the optical axis of the objective with the axis YY ', said field mirror, for possibly ensuring the nullity of the dead time of scanning between two consecutive lines, having at most a width in the x-direction slightly smaller than the length of the analyzed line itself equal to the distance between the images of the detector in two consecutive faces of the drum rotating, said mirror being animated o u not a movement of small amplitude 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 about 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.

  The operation according to the present invention relates to an embodiment of the line scanning means and more particularly of the symmetrical system with respect to the image transport plane P of the sensitive element at a fixed point A 'of

the YY axis.

  In the patent application, this transport system

  is mainly described in the form of a toroidal mirror of

  elution around YY 'of elliptical section, by a plane containing

  YY 'and whose main axis is occupied by the sensitive element.

  According to another embodiment, the transport system of i-

  , nagA at A 'of the sensor on the axis YY' belonging to the line scanning means is a lens A, the sensitive element being outside the axis YY ', the focal length of the lens being determined so that the image A 'on YY' of said sensitive element

  is located with respect to D as previously indicated.

  The use of an ellipsoid according to the first embodiment recalled is not very suitable when the sensor has

  large enough because the ellipsoid is not flat

  Netique. This is for example the case when this sensor is constituted

a mosaic of detectors.

  The use of image transport by means of an ob-

  lens lens according to the second embodiment has the disadvantage of excluding from the analysis of objects, a whole part of the spectrum of light, including a large part

infrared and visible spectrum.

  According to the present invention, these

convenients and inadequacies.

  Instead of using an ellipsis, it is proposed to use

  be the set of two paraboloids of revolution around the axis

  YY 'mounted face to face so that they combine optical-

  the sensor A with the point A 'of the axis YY'. Such a couple of

  mirrors being aplanatic allows the use of

  sez large dimensions mosaic-shaped detectors instead

  a single detector of restricted dimensions.

  In the case where the detector is placed outside the axis YY ', the invention uses an image transport means at A' located on the axis YY ', consisting solely of mirrors such that the analysis is performed in both the visible and the infrared. More particularly, this image transport means comprises the two preceding paraboloids of revolution, one

  of them having been rotated so that its axis of revo-

  Cutting YY 'and its reflecting surface is opposite YY', the sensor being placed at its focus outside the axis YY ', a system of planar mirrors possibly

  the bending of the beam between the two paraboloids.

  The invention will be better understood with the aid of the description

  following two examples given by way of example.

  non-limiting examples, the said description being accompanied by

  which represent: - Fig. 1 - A sectional representation of an embodiment of the device which is the subject of the main patent whose means

  line scan are equipped with the system, according to the present

  image transport of the sensor located on the rotational axis.

the device.

  - Fig. 2 - A partial representation in section of a mode of re-

  embodiment of the device which is the subject of the main patent whose line-scanning means are provided with the mirror system, according to the present invention, of image transport of the sensor located

  outside the axis of rotation of the device.

  For Figure 1 is found in a section through its plane P symmetry the overall structure of the device subject to the main patent. Under number 11 is indicated a fixed lens whose optical axis is 12 and focus F. The objective

  11 is shown in this figure as realized with the aid of

  daughters. It is known from the main patent that this objective can just as easily be made from mirrors. The optical axis 12 intersects the axis YY 'at point E. The axis YY' is the axis of rotation of a system comprising a drive device 13 and a

  drum 13 'laterally bearing a large number of reflecting faces

  chissantes. As indicated in the main patent, this drum can have several forms. It is supposed here prismatic, its reflective faces spread regularly around

  the YY axis. One of its faces is represented in 17 in a po-

  sition perpendicular to the plane P. The plane 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

  by E. This arrangement shown in Figure 1 is only

  Preferably, in the case where the device, as indicated in the main patent, is provided with additional means to obtain the direct visualization of the field by means of 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 an image located in said field

  sibly on this last mirror. In Figure 1, the beam

  particular indicated is that which has a mean radius

  melted with the optical axis 12, the image being formed at the point D on the axis ZZ 'perpendicular to YY', corresponding to the center of the field.

  The mirror 14 ensures the scanning of the field along the di-

  roction y 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.

  According to the present invention the device comprises a

  concave mirror formed from the set of two portions of parabola

  loide respectively 18 and 18 'of revolution about the axis YY' and whose reflective surfaces are opposite. The vertices of these parabololds are respectively S and S 'and the foci A and A'. They are located on YY '. A 'is symmetrical to D with respect to drum end 17. Said mirrors form the detector 19

place <-n Has an image in A '.

  The system constituted by the rotating drum 13 ', the

  mirrors 18, 18 'and the detector 19 makes it possible, during the rota-

  said drum, the analysis, line by line, according to the direc-

  perpendicular to the plane of the sheet of the field image,

  given by the objective 11 and the image analysis mirror 14 to the

  This system constitutes the line analysis or x analysis system. The mirror 16 symmetrical with respect to the plane (ZZ ',

  YY ') and whose summit is in the vicinity of D ensures the conjugacy

  its optics of the center of the exit pupil O of the objective 11 with the fixed point 0 'of the axis YY', symmetrical of E with respect to ZZ ', so as to ensure the convergence on the detector 19 of

  any beam resting on the exit pupil of the objective 11.

  This mirror 16 in that it delimits the field analyzed constitutes

what is called a field mirror.

  In Figure 2 the overall structure of the device is not recalled. Not shown, in section according to plan

  symmetry of the device, that the elements necessary for the

  description of the particular contribution of the invention. In this figure,

  we find the axis YY 'of rotation of the device, the point A' sy-

  of the point D with respect to the face 17 of the drum, the por-

  paraboloid 18 'placed as shown in Figure 1,

  that is, with A 'as focus, and its vertex S' on YY '.

  In this figure the sensor 19 is located at the point A ex-

  tery to the YY 'axis and the 18' parabolo. According to the invention A and A 'are optically conjugated by means of only mirrors. For this, a first step is taken to bend the optical beam and direct it outside the paraboloid 18 '. This bending is

  obtained by means, for example, of the plane mirror 21 inclined to the

  beam of parallel rays reflected by the mirror 18 'and whose reflective surface for example perpendicular to the plane of the

  look at point A. A second step taken by the

  vention is to focus the beam reflected by the plane mirror

  point A, on the detector 19 by means of a portion of para-

  boloide 20 for example symmetrical with respect to the plane of the figure and focus and vertex respectively A and S. It goes without saying that the two parabololdes, just as elsewhere in FIG.

  you do not have to be absolutely identical. Moreover, on the

  FIG. 2, a single inclination plane mirror 45 by ranport at YY ',

  is used so that A and S are located on the Yl axis. Yil, per-

  pendicular A YY '. It goes without saying that the invention also provides for the use, in the case of a detector located outside the axis YY ',

  of a bending mirror 21 of inclination other than 450 with respect to

  port to YY 'or the use of several reflective mirrors

  successively the beam from the paraboloid 18't, likewise

  that according to the invention the axis of the paraboloid 20 is not necessarily

  perpendicularly to the YY 'axis.

  A remarkable result obtained by the invention, with such embodiments of line scanning, is that the distance AA 'can be relatively arbitrary because the optical path

  between parabololdes is carried out in parallel bundles, which allows

  put them away, whether or not the detector is on YY '. This is not the case when the image transport of the detector located on the axis YY 'is carried out using an ellispsoide, the distance AA'

  being then necessarily the distance between foci. According to the

  vention the detector can be placed easily far enough from the axis YY 'position eminently favorable ai said detector is attached to auxiliary means, large volume and necessary for its

  operation, such as for example a cryogenic machine.

  It goes without saying that the embodiment of the system of

  image transport of the detector on the axis of rotation YY 'is

  in the embodiments of the opticomechanical scanning device according to the main patent and that the devices

  thus obtained are part of the present invention.

Claims (3)

CLAIMS:   1. Optical scanning device of a field of vision   divided into different areas and viewing said field, dis-   wherein said scanning is performed according to two di-   perpendicular rections namely, in a direction x a scan called line scan and in another direction y a   sweep called sweep frame or image, device operating them-   said scans according to beams from different areas   of the field and ensuring the convergence of said beams on a   radiation-sensitive content of said beams,   positive, usually in the order, according to the meaning of the   path of the median incident beam from the field of view, an ob-   jitter, weft scanning means in the y direction, a system   method of folding the beams delimited by the aperture of the objective towards means for scanning line of the image field of the objective in the direction x and the sensitive element, said   means of line scanning, the sensitive element, possibly from   very elements related to those previously mentioned for the direct visualization of the image of the analyzed field, the means of said device being as follows: the objective at its optical axis included in a plane P containing   the direction y and perpendicular to x, and said objective is inter-   changeable, its focal surface being curved and such that its center   curvature is located in the center of the exit pupil of the ob-   jectif, - the raster scanning means consist of a plane mirror rotating reciprocating about an axis parallel to the x direction, placed in a converging beam behind the objective near   of the image of the field in said objective.   the line scanning means consist on the one hand of a drum in uniform rotation about a fixed axis YY 'contained in   said plane P and carrying a large number of reflecting plane faces.   regularly distributed around the drum, and,   on the other hand, a symmetrical image   port to said plane P forming an image of the sensing element at a fixed point A 'of the drum rotation axis YY', said drum being placed in a convergent beam in the path of said transport system on the image side of the element sensitively symmetrical to 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 focus of the lens with respect to the weft mirror in parallel position YY', The optical system for folding the beams is constituted by a so-called concave mirror of a field admitting the plane P as a plane of symmetry and whose vertex is placed in the vicinity of D in the axis ZZ 'passing through D and perpendicular to YY'. . said mirror being determined so that it conjugates the center O of the exit pupil of the objective with a fixed point 0 'of the axis YY', said point O '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 an alternating   native 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 weft scanning means, the amplitude of said rotation being such that she   ensures the 0 'fixity of the conjugate by the field mirror of the   0 of the exit pupil of the objective during the alternative rotation of the frame scanning means, characterized in that the image transport system of the detector located on the axis YY '-st consists of a set of two concave mirrors in the form of portions of paraboloids of revolution, of common axis YY ', and whose reflective surfaces are opposite, the focus of one being at point A' the focus of the other being occupied by the sensitive element. 2. Optical scanner for a field of view   divided into different areas and viewing said field, dis-   wherein said scanning is performed according to two di-   perpendicular rections ie, in a direction x a baseline   A so-called scanning scan line and following another direction y a scan called frame or image scan, device operating said scans sel.n beams from different areas   of the field and ensuring the convergence of said beams on a 616-   radiation-sensitive radiation contained in said beams,   system generally comprising, in the order of the direction of the path of the median incident beam coming from the field of view, an objective, a raster scanning means in the y direction, a system for folding the beams delimited by the opening of the objective towards line scanning means of the image field of the objective in the direction x and the sensitive element, said   means of line scanning, the sensitive element, possibly from   very elements related to those previously mentioned for the direct visualization of the irage of the analyzed field, the means of said device being as follows: the objective has its optical axis included in a plane P containing the direction y and perpendicular A x, in that said lens is interchangeable and that its focal surface is curved and that its center of curvature is located at the center of the exit pupil of the objective, the frame scanning means consist of a rotating plane mirror of reciprocating about an axis parallel to the x direction, placed in a converging beam behind the lens 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 of the axis of transportation of the element of the image of the element sensitive, symmetrical said point A 'with respect to each face of the drum   when said face is nerpendicular to the plane P being in the vicinity   swimming from point D symmetrical to the focal point of the objective with respect to the frame mirror in the parallel position A 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 'running at D and perpendicular to YY', said mirror being determined so that it conjugates the center O of the exit pupil of the objective with a fixed point 0 'of the axis YY', said point 0 'being symmetrical with respect to ZZ' of the point of intersection of the optical axis of the objective with the axis YY ', said field mirror to ensure possibly the nullity of the dead time of scanning between two consecutive lines having at most a width in the x direction slightly smaller 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 a movement of small amplitude in -lase with the movement of the weft scanning means, said small movement comprising on the one hand an alternative translation along the axis ZZ 'in the vicinity of D and an alternative rotation around a   axis parallel to the direction x symmetrical with respect to ZZ ', the   plitude of said translation being such that it corrects   focusing introduced by the frame scanning means, the amplification   a study 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 lens during the alternative rotation of the frame scanning means, characterized in that the image transport system of the detector located off axis YY 'consists of a   set of two concave mirrors in the form of   lots of revolution, one admitting YY 'for axis of symmetry and A' for focus, the sensitive element being located at the focus of the other,   a system of plane mirrors providing parallel light   beam mission from one paraboloid to another.   3. Device subject to the main patent in which the detector's image transport system is introduced   on the axis YY 'according to one of claims 1 or 2. -