PERITELESCOPE

Abstract: A peritelescope comprising elevation scanning appar­ atus (30) and azimuth scanning apparatus (32), the elevation scanning apparatus (30) and azimuth scanning apparatus (32) being operative and cooperative to provide a 360 degree field of view in elevation and a 360 degree field of view in azimuth.

Description: FIELD OF THE INVENTION The present invention relates to optical apparatus providing selectably directional viewing along an azimuth generally and more particularly to peritelescopes. BACKGROUND OF THE INVENTION Various types of peritelescopes are known in the art and are available on the market. Most of the peritelescopes presently on the market have limitations in their range both in azimuth and in elevation. In order to overcome the limitations in elevation range, most of the devices employ a pivotable elevation scan mirror or prism which pivots about an axis extending through the mirror and extending perpendicularly to the beam of light reflected or refracted thereby. This prior art structure imposes a limitation at high elevation angles, approaching 90 degrees to the horizontal, wherein the dimensions of the mirror or prism limit the extreme elevation angles which can be realized. There is also known peritelescope apparatus wherein azimuth scanning is provided by rotation of the elevation mirror assembly about a rotation axis which is parallel to the beam reflected by the elevation mirror assembly. The image distortion produced thereby is corrected by means of a rotating prism which rotates in the azimuth by an angle equal to one-half of the rotation of the elevation mirror assembly from a predetermined reference. SUMMARY OF TtlE INVENTION The present invention seeks to provide an improved peritelescope having significantly enhanced performance as compared with the prior art. There is thus provided in accordance with a preferred embodiment of the present invention a peritelescope comprising elevation scanning apparatus and azimuth scanning apparatus, the elevation scanning apparatus and azimuth scanning apparatus being operative and cooperative to provide a 360 degree field of view in elevation and a 360 degree field of view in azimuth. Further in accordance with a preferred embodiment of the present invention there is provided a peritelescope comprising elevation scanning apparatus and azimuth scanning apparatus, the elevation scanning apparatus comprising pivotable beam reflecting means which are pivotable about an axis parallel to the beam reflected thereby. Additionally in accordance with a preferred embodiment of the present invention there is provided a peritelescope comprising elevation scanning apparatus and azimuth scanning apparatus, the elevation scanning apparatus comprising pivotable beam reflecting means which are pivotable about an axis parallel to the beam reflected thereby. Additionally in accordance with a preferred embodiment of the present invention, there is provided a peritelescope comprising elevation scanning apparatus and azimuth scanning apparatus, the azimuth scanning apparatus comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an elevation scanning axis and the azimuth scanning apparatus comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis and wherein the elevation beam reflecting means is spaced from the azimuth scanning axis. Further in accordance with an embodiment of the present invention, there is provided a peritelescope comprising elevation scanning apparatus, azimuth scanning apparatus, and image orientation correction apparatus, the elevation scanning apparatus comprising pivotable elevation beam reflecting apparatus arranged for pivotal motion about an elevation scanning axis and the azimuth scanning apparatus comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis and wherein the image orientation correction apparatus comprises a rotating optical element, and apparatus for causing rotation of the rotating optical element as a function of the rotation of the elevation beam reflecting apparatus about the elevation scanning axis and of the rotation of the azimuth beam reflecting apparatus about the azimuth scanning axis. Further in accordance with an embodiment of the present invention, the apparatus for causing rotation comprises a differential. Still further in accordance with an embodiment of the invention there is provided a peritelescope comprising elevation scanning apparatus, azimuth scanning apparatus, image orientation correction apparatus, and a movable exit pupil, the elevation scanning apparatus comprising pivotable elevation beam reflecting apparatus arranged for pivotal motion about an elevation scanning axis and the azimuth scanning apparatus comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis and wherein the movable exit pupil is pivotable about the azimuth scanning axis. Additionally in accordance with a preferred embodiment of the present invention, there is provided exit pupil differential coupling apparatus for coupling the movable exit pupil to the image orientation correction apparatus, whereby rotation of the exit pupil about the azimuth scanning axis does not affect the image seen therethrough. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Fig. 1 is a block diagram mechanical illustration of a peritelescope constructed and operative in accordance with a preferred embodiment of the invention; Fig. 2 is a schematic illustration of the peritelescope of the present invention indicating the mechanical linkages between the various elements; Fig. 3 is an optical diagrammatical illustration of the peritelescope illustrated in Fig. 2; Fig. 4 is a pictorial illustration of a portion of the peritelescope illustrated in Fig. 2; and Fig. 5 is a pictorial illustration of another portion of the peritelescope illustrated in Fig. 2. DETAILED DESCRIPTION OF THE INVENTION Reference is now made to Fig. 1, which is a block diagram - illustration of the peritelescope constructed and operative in accordance with a preferred embodiment of the present invention. The peritelescope comprises elevation scanning apparatus 10 which is operative to orient an elevation beam reflecting surface, such as a mirror or prism, at a predetermined angle o( about the y axis. The peritelescope also comprises azimuth scanning apparatus 12 which is operative to orient an azimuth beam reflecting surface, such as a mirror or prism, at a predetermined angle ss about the z axis. Apparatus 10 and apparatus 12 are mechanically coupled by a mechanical summing device 14, preferably a differential which provides a rotational mechanical output about the z axis which may be expressed as: EMI6.1 The mechanical output from summing device 14 is supplied to a second mechanical differential 16, which is operative to provide a rotational mechanical output / to a rotatable image orientation compensation prism 18 and is also mechanically coupled to a rotatable exit pupil 20, whose orientation about the z axis is indicated as The angular relationship between A, f and W is given as follows: : EMI6.2 Reference is now made to Fig. 2 which is a schematic illustration of a preferred embodiment of the peritelescope of the present invention indicating the mechanical linkages between the various elements. Reference is also made to Figs. 4 and 5 which are pictorial illustrations of portions of the apparatus of Fig. 2. An elevation mirror 30 is seen to be mounted for selectable rotation about the Y-axis. The Y-axis is defined to lie in a plane perpendicular to the Z-axis, which extends vertically. The orientation of elevation mirror 30 with respect to the Y-axis is defined by an angle An azimuth mirror 32 is arranged to receive radiation reflected from elevation mirror'30 and is mounted for rotation about the Z-axis. The orientation of azimuth mirror 32 about the Z-axis with respect to a predetermined reference is indicated by Fixedly mounted onto aximuth mirror 32 for rotation together therewith about the Z-axis is a right angled rotational mounting element 34, including a first portion 36 extending parallel to the' Z-axis and a second portion 38 extending in a plane parallel to the Y-axis. Coupled to elevation mirror 30 for rotation together therewith about the Y-axis is a gear or gear equivalent 40. Element 40 engages an intermediate gear element 42 which is rotatably mounted with respect to portion 38. Fixedly mounted with respect to intermediate gear element 42 and rotatably mounted with respect to portion 38 is a bevel wheel type gear 44, which in turn engages a summing bevel wheel type gear or equivalent 46, which is arranged for rotation about the Z-axis. The effective gear ratio between element 40 and summing gear 46 is +1 : +1. It may be appreciated that elements 34, 110, 42, 44 and 116 perform a summing function in accordance with the following equation: EMI8.1 where 5 is the angular orientation of element 116 about the Zaxis with respect to a predetermined reference. Element 46 is fixedly coupled to a parallel bevel gear type or equivalent element 118 which also rotates about the Zaxis,together with element 46. Element 48 defines one gear of a differential 50, which also comprises an intermediate gear 52 and a terminal gear 54, which is also arranged for rotation about the Z-axis. Rotatably mounted with respect to intermediate gear 52 is a rotation prism 56 which is operative to correct the received image for distortions produced by image rotation. The mounting of prism 56 is such that it is rotatable about the Z-axis, its orientation about the Z-axis being given by4 Fixedly mounted onto element 54 for rotation about the Z-axis is a movable exit pupil assembly 58 comprising a viewing mirror 60, or its equivalent. The orientation of the viewing mirror 60 about the Z-axis is indicated by -if . The differential 50 is arranged to define the following relationship between the elements and orientations defined hereinabove: EMI9.1 <tb> ss <SEP> ¯¯¯¯¯¯¯¯¯¯¯¯¯ <SEP> + <SEP> o <SEP> + <SEP> Constant <SEP> (4) <tb> <SEP> 2 <tb> It may be appreciated that the movable exit pupil assembly 58 may be moved to any desired position about the Z-axis and the viewer will see the same scene, since the appropriate corrections to the image are being made automatically by suitable rotation of the rotating prism 56, through operation of the differential 50. Reference is now made to Fig. 3 which is an optical diagrammatical illustration of the peritelescope illustrated in Fig. 2. For simplicity, the same reference numbers are used in Fig. 3 as in Fig. 2 to indicate corresponding elements. It is seen that an important feature of the present invention lies in the fact that the reflected beams lie parallel to the rotation axes of the rotating elements. Particularly it is seen that the elevation mirror 30 is oriented such as to provide a reflected beam along the Y axis to the azimuth mirror 32, which, in turn, provides a reflected beam along the Z-axis to the viewing mirror 60 or its equivalent. The feature that the reflected beams lie parallel to the rotation axes of the rotating mirror elements is important .] since it enables 360 degree scanning by each of the elements. Correction of image distortions produced by rotation is provided by a dove prism 56, or its equivalent, which is rotatably mounted about the Z-axis in a manner described hereinabove. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow:

Claims: CLAIMS 1. A peritelescope comprising: elevation scanning means; and azimuth scanning means, said elevation scanning means and azimuth scanning means being operative and cooperative to provide a 360 degree field of view in elevation and a 360 degree field of view in azimuth. 2. A peritelescope comprising: elevation scanning means; and azimuth scanning means, said elevation scanning means comprising pivotable beam reflecting means which are pivotable about an axis parallel to the beam reflected thereby. 3. A peritelescope comprising: elevation scanning means; and azimuth scanning means, said elevation scanning means comprising pivotable elevation beam reflecting means arranged for pivotal motion about an elevation scanning axis and the azimuth scanning means comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis and wherein said elevation beam reflecting means is spaced from said azimuth scanning axis. 4. A peritelescope comprising: elevation scanning means; azimuth scanning means; and image orientation correction means, said elevation scanning means comprising pivotable elevation beam reflecting means arranged for pivotal motion about an elevation scanning axis, said azimuth scanning means comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis, and said image orientation correcting means comprises a rotating reflecting element, and means for causing rotation of the rotating reflecting element as a function of the rotation of the elevation beam reflecting means about said elevation scanning axis and of the rotation of the azimuth beam reflecting means about said azimuth scanning axis. 5. A peritelescope according to claim 4 and wherein said means for causing rotation comprises a differential. 6. A peritelescope comprising: elevation scanning means; azimuth scanning means; image orientation correction means; and a movable exit pupil, said elevation scanning means comprising pivotable elevation beam reflecting means arranged for pivotal motion about an elevation scanning axis, said azimuth scanning means comprising pivotable azimuth beam reflecting means arranged for pivotal motion about an azimuth scanning axis; and said movable exit pupil being pivotable about the azimuth scanning axis. 7. A peritelescope according to elaim 6 and also comprising exit pupil differential coupling means for coupling the movable exit pupil to the image orientation correction means, whereby rotation of the exit pupil about the azimuth scanning axis does not affect the image seen therethrough.

Inventors: DAGAN, JACOB
Applicants: STATE OF ISRAEL MINISTRY OF DEFENCE ARMAMENT DEVELOPMENT AUTHORITY
Application year: 1985
Main classification: G02B23
IPC codes: G02B17, G02B23, G02B7, G02B27