FR2569016A1 - DEVICE FOR THE HARMONIZATION OF THE OPTICAL AXES OF A SIGHT - Google Patents

Abstract

DEVICE FOR THE HARMONIZATION OF THE OPTICAL AXES OF A VIEWFINDER CONSTITUTES AT LEAST TWO OPTICAL DEVICES PREFERABLY HAVING DIFFERENT FREQUENCY RANGES, THE OPTICAL AXIS OF THE FIRST DEVICE2 FORMING AN ANGLE OF 90 WITH THE OPTICAL AXIS OF THE SECOND DEVICE3 AND FOR EACH ADDITIONAL EQUIPMENT, A REFERENCE PRISM4 ARRANGED AT AN ANGLE OF 45 BEING LOCATED AT THE POINT OF INTERSECTION OF THE AXES. A TRIPLE MIRROR5 IS PROVIDED IN THE EXTENSION OF THE OPTICAL AXIS OF THE SECOND UNIT3. A RETICLE PROVIDED FOR IN A IMAGE PLAN7 OF THE FIRST APPARATUS2 MAY, IN CONJUNCTION WITH A LENS12, BE PROJECTED VIA THE REFERENCE PRISM4 AND THE TRIPLE MIRROR5 IN A IMAGE 7A OF THE SECOND APPARATUS3. THE SIMULTANEOUS PROJECTION OF THE RETICLE OR REGISTRATION POINT PRESENT IN THE IMAGE PLANS 7 AND 7A LEADS TO THE AUTOMATIC HARMONIZATION OF THE AXES OF DEVICES 2 AND 3, SO THAT USUAL COLLIMATORS OR EXTERNAL CONTROL DEVICES CAN BE ELIMINATED.

Description

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  1 Device for the harmonization of the optical axes of a viewfinder The invention relates to a device for the harmonization of the optical axes of a viewfinder consisting of at least two optical devices preferably having different frequency ranges, and employing

  at least one return prism. For the harmonization of the axes,

  Known positives of this type require additional elements, such as, for example, collimators or optical cues. In

  devices of this type fitted with thermo

  ision, such as those known from patent application DE-29 41 627, the diameter of the collimator must have the same order of magnitude as the diameter of the optics of the thermo-vision device, because the optics have limited curvature. This results in very large collimator diameters, and a

  considerable increase in size in the viewfinder space.

  When during the aiming process carried out using these additional auxiliary means to harmonize the axes, the axes of the optical devices have shifted with respect to each other due to external influences such as thermal voltages,

  vibrations and shocks, or even due to synchronization errors

  nation in the thermo-vision device, a new adjustment of the axes must be carried out each time. When performing a

  aiming process with these additional elements for the harmoni-

  the axes of the incorporated optical devices, it is therefore necessary

  Always check the parallelism of the viewfinder axes.

  The invention aims to provide a device for har-

  monization of the optical axes of a viewfinder which makes it possible to eliminate the abovementioned drawbacks, and which permanently allows a totally reliable harmonization of the optical axes of the viewfinder. This objective is achieved by means of a device characterized in that the optical axis of the first device forms an angle of 90 with the optical axis of the second device and of each additional device, the return prism disposed at an angle of 45 being each time

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  1 located at the point of intersection of the axes, that the optical output of the device

  sitive towards the scene is carried out in the extension of the optical axis

  of the first device, and that a triple mirror is placed in the extension

  gation of the optical axis of the second device and of each additional device. According to an additional characteristic, a point of

  marker or reticle is in an image plane of one of the devices

  optical reils, reticulequi which, via the prism of return and triple mirrors, projected in an image plane of each of

  other optical devices. According to another characteristic, the ob-

  a target is serviced as desired by each of the optical devices, either directly via an eyepiece placed on the device, or indirectly via the screen of a cathode ray tube, passing by a return prism or a deflection mirror. According to a last characteristic, finally, the first optical device is a thermo-vision device provided with a cathode ray tube for reproducing the thermal image, the second optical device is a telescope, a third optical device is a television camera, and a fourth optical device is

a goniometer.

  The arrangement provided by the invention provides a remarkable solution.

  fairly simple to automatically and absolutely harmonize all the optical axes of a viewfinder. Since the only additional equipment required is a triple mirror for each additional optical device from the second, the price of a viewfinder according to the invention is considerably reduced compared to that of known viewfinders, equipped with collimators or the like.

  additional control devices.

  The invention has the essential advantage of not requiring the stability of the elements for the harmonization of the axes. Since a reference point or reticle is only necessary in one of the optical devices of the reticle sight which, via the path of the rays passing through the return prism and the triple mirror, is reproduced with absolute reproduction precision in each of the other optical devices, independently of the stability of the axes, one by one to the other, external influences,

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  1 and in particular severe surrounding military nuisance,

  no influence on the accuracy of the viewfinder axes. When

  servation of a target, the axes of different optical devices can, using the same reticle viewed or detected in all devices, be constantly prevented from moving away from each other - as often happens in known sights . The observation of the target can here be carried out as desired by any of the

incorporated optical devices.

  The description which follows explains the invention with the aid of examples.

  of realization figured on the attached drawing. This drawing shows in Figure 1 the principle of construction of a viewfinder with two optical devices; in Figure b a highly simplified representation of a viewfinder

  equipped with four optical devices; and -

  in Figure 3 the schematic representation of a form of realization

  sation of a viewfinder mounted in a housing, and provided with a device

thermo-vision and a telescope.

  The viewfinder 1 presented on the block diagram 'of Figure 1 consists of a first optical device 2, a second optical device 3 offset by 90 relative to the first device in the same plane of optical axes of a reference prism 4 and a triple mirror 5. The optical devices shown in Figure 1- and the following figures

  are preferably devices of the type working with

  visible or infrared frequencies. The reference prisms must, as is known, be designed so that they pass the

  high frequency waves having given frequencies, and that they

  see waves with other frequency frequencies. A triple mirror is a mirror system made up of three individual mirrors arranged in different planes and joining in a trihedron. The incident light is reflected in the direction of incidence, regardless of the angle of incidence. The two optical devices 2 and 3 are here each provided with an eyepiece 6. A real or projected reticle is present in an image plane 7 of only one of the optical devices 2 or 3, for example of the device 2. In the figure, the eye 8 represents a pointer. For the optical device 3, there is also arranged in front of the eyepiece 6 a

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  1 deflection mirror 9. If for example the optical device 2 is a thermo-vision device and the optical device 3 a telescope

  diurnal, the return prism 4 lets the ray pass directly-

  thermal radiation arriving in the viewfinder 1, and reflects the visible light in the telescope 3. The radiation 10 arriving in the thermo-vision device is in known manner transformed into a thermal image, and can be observed by the eyepiece 6. The reticle 7 is deflected by the return prism 4 towards the triple mirror 5, from where it is returned and projected according to the ray path 11 in the diurnal telescope 3. We can therefore see in the image plane 7a the same image 12 and the same reticle as in the image plane 7. Conversely, it is also possible to project in the image plane 7 of the apparatus 2 a reticle

  present in the image plane 7a of the apparatus 3. It is advisable to pro-

  throw from larger diameter optical device towards the device

  smaller diameter optics. For automatic tracking

  jective, a real or projected reference point or reference point may be present in place of the reticle in the image plane 7 or 7a, and be

projected in the other plane.

  Figure 2 shows a viewfinder 20 with four optical devices

  ques, which work in different frequency ranges. It is a thermo-vision device 2 "looking" directly at the scene, a day-time telescope 3, a television camera 21

  and a goniometer 22. According to the different frequency ranges

  for which the different devices are sensitive, different reference prisms 4, 23 and 24 have been arranged. The triple mirrors 5 can be identical for all the devices. The radius paths 10 and 11 explained above with the aid of FIG. 1 reproduce for all the apparatuses 2, 3, 21 and 22, so that the reticle placed in the image plane 7 can also be projected in the image planes 7a, 7b and 7c of the other devices. Figure 2

  particularly highlights the advantage provided by the invention.

  With the known devices, obtaining harmonization of the axes for four optical devices requires a significant expense in additional parts, and a particularly rigid positioning of the devices and return prisms. With the present

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  1 viewfinder 20, the harmonization of the axes does not require any particular stability of the different elements. The axes of the four optical devices cannot deviate from each other, since the single reticle 7 can be permanently viewed or detected in the other devices. In addition, it is immaterial that the eye 8 of the pointer aims at the objective 12 by the diurnal telescope 3, the camera of

  television 21 or the thermo-vision device 5.

  FIG. 3 schematically shows a viewfinder 30 which is shown

  tee in a housing 31, and which corresponds approximately to the

  positive of FIG. 1, provided with a thermo-vision device 32 and a daytime telescope 33. A cable 34 connects to the thermo-vision device 32 a cathode ray tube 35, the screen 36 of which is turned towards a monocular 37. The thermo-vision device 32, the diurnal telescope 33 and the cathode ray tube 35 are directly mounted on the wall of the housing 31. A return prism 38 is, using bars 39, attached to the daytime lens 33. A triple mirror 40

  is mounted on the housing 31 using a frame 41. The eye 8 of the pin

  tor can, via an image window 42 practiced

  in the housing 31, observe the scene comprising the objective 12, simul-

  temporarily as a thermal image on the screen 36 of the cathode ray tube

  35, and in the diurnal bezel 33 via a return prism 43. The constituent elements of this viewfinder 30 can

  be knowingly mounted in the housing by means and

  simple fixing devices, since the harmonization of the axes of

  the thermo-vision device 32 and the diurnal bezel 33 is constam-

  and automatically provided by the reticle projected in

  the two devices, in the image planes 7 and 7a.

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Claims (4)

  1 1. Device for the harmonization of the optical axes of a viewfinder consisting of at least two optical devices preferably having different frequency ranges, and using at least one return prism, characterized in that the optical axis of the first device (2) forms an angle of 90 with the optical axis of the second device (3) and of each additional device (21, 22), the return prism (4, 23, 24) arranged at an angle of 45 being each time located at the point of intersection of the axes, that the optical output of the device towards the scene is carried out in the extension of the optical axis of the first apparatus, and that a triple mirror (5) is arranged in the extension   of the optical axis of the second device and of each additional device   mental. 2. Device according to claim 1, characterized in that a reference point or reticle is in an image plane (7) of one of the optical devices (2, 3, 21, 22), reticle which is, via the reference prism (s) (4, 23, 24) and mirrors   triple (5), projected in an image plane of each of the other devices optical reils.   3. Device according to claim 1 or 2, characterized in that the observation of an objective (12) is carried out as desired by each of the optical devices (2, 3, 21, 32, 33), either directly by via an eyepiece (6, 37) placed on the device, either indirectly via the screen (36) of a cathode ray tube   (35), passing through a return prism (43) or a deflection mirror tion (9).   4. Device according to any one of the preceding claims.   teeth, characterized in that the first optical device (2,   32) is a thermo-vision device provided with a cathode ray tube   dique (35) to reproduce the thermal image, that the second optical device * 30 is a telescope (3, 33), that a third optical device is a television camera (21), and that a fourth optical device is a goniometer (22).