US3588250A - Telemetric telescope for direct firing arms - Google Patents

Abstract

RESPONDING TO THE RANGE OF THE POINT FOR WHICH THE TELEMETER IS ADJUSTED THROUGH IMAGE COINCIDENCE.

A TELEMETRIC TELESCOPE PROVIDING COINCIDENCE BETWEEN TWO IMAGES ENSURING ON THE ONE HAND THE OBSERVATION OF AN AREA TO BE WATCHED AND ON THE OTHER HAND THE MEASUREMENT OF THE DISTANCES OF TARGETS LYING IN SAID AREA, THE TELESCOPE IS ADAPTED TO GIVE THROUGH A MERE SIGHTING AND WITHOUT ANY FOCUSING THE DISTANCE OF AT LEAST ONE PREDETERMINED POINT OF THE FIELD OF FIRE AND ACCORDING TO A MODIFICATION THE TELESCOPE MAKES THE ARM CARRYING IT ASSUME THE ANGLE OF ELEVATION COR-

Description

D United States Patent 11113533350 [72] lnventors Francois Arene [56] Reference Cited 46 Besslerw UNITED STATES PATENTS Rue 2,401.705 6/1946 Mihalyi 356/9 2,632,357 3/1953 Mihalyi 356/8 P 613396 2964991 12/1960 Coeytaux etal. 356/9 [22] PM 1967 1 429 981 9/1922 Taylor et al 356/7 [45] Patented June 28, 1971 [32] Priority Feb. 9, 1966 Primary Examiner-Ronald L. Wibert [33] France Assistant Examiner0rville B. Chew ll [31] 49,011 Attorney-Young & Thompson m ABSTRACT: A telemetric telescope providing coincidence between two images ensuring on the one hand the observation {541 TELESMETRIC TELESCOPE FOR DIRECT FIRING of an area to be watched and on the other hand the measure- 4 D F ment of the distances of targets lying in said area; the rawmg telescope is adapted to give through a mere sighting and [52] U.S.Cl 356/8, Without any focusing the distance of at least one predeter- 356/247 mined point of the field of fire and according to a modification [5 1] Int. Cl G0lc 3/04 the telescope makes the arm carrying it assume the angle of [50] Field of Search 356/7, 8, 9, elevation corresponding to the range of the point for which 255 the telemeter is adjusted through image coincidence.

TELEMETRIC TELESCOPE FOR DIRECT FIRING ARMS BACKGROUND OF THE INVENTION Our invention relates to telemetric telescopes that is to optical instruments adapted on the one hand to ensure observation of an area to be watched and on the other hand to mea sure distances within said area.

Our invention relates ,chiefly to the application of telemetric telescopes to fire arms provided for direct firing and more particularly to infantry arms.

Our improved telescope is designed so as to provide through a mere sighting and without any focusing the range of at least one predetermined point of the field of fire and according to a modification it gives the arm carrying it the angle of elevation corresponding to the range of the point with reference to which the telemeter has been adjusted through coincidence of images.

PRIOR ART Telemetric telescopes are already known which allow when taking aim and giving the arm the desired angle of elevation for ensuring telemetric coincidence of the two images of a target as seen by the marksman to obtain the angle of elevation or sight corresponding to the range of said target.

Such a telemetric telescope forms the object of the French Pat. No. 1,117,609 filed on Dec. 29, 1954 in the names of Coettaux, Deramond (one of the present applicants) and Hugues and entitled Optical laying instrument for the direct firing of arms.

The invention underlying said patent has'also formed the object ofthe US. Pat. No. 2,964,991 of Dec. 20, 1960.

The telemeter disclosed in said prior patent forms-in the observer's eye two images of the field of fire through two optical paths or systems the axes of which directed towards the field are vertically shifted with reference to each other as already known in the art. The coincidence between the images of different targets at different distances is obtained by giving the telemeter rigid with the arm a slope corresponding to the angle of elevation.

The coincidence between the images is obtained through a distortion of the magnification as to sight of a lens in one of the optical paths. Said distortion consists in giving a slope by a given angle to the aiming line directed towards the target along said optical path with a view to obtaining thus an optical coincidence between the two images. Calculation allows matching with a predetermined accuracy the distortion obtained through the slope of the telemeter with reference to the target aimed at with a modification of the parallaxis between the lines of sight in the two telemetric paths. This allows thus the images to coincide in the observers eye while giving the arm rigid with the telemeter the angle of elevation corresponding to the target aimed at.

Our invention covers modifications of such a type of telemetric telescope. The optical system is different and it may be given different shapes one of which provides telemetric coincidence between the images for a single distance of the target in the field of fire while another provides coincidence for a larger number of different distances.

Furthermore, our invention associates an optical system providing observation within a large field of fire with such a telemetric telescope.

SUMMARY OF THE INVENTION In principle, the telemetric telescope includes two vertically shifted optical paths providing each an image of the field of fire and the sighting axes of the said paths in said field converge through the very structure of the telescope at a predetermined unvarying distance from the telescope. Furthermore, a third optical system forming the actual observing telescope produces an image which is independent of those produced through the telemetric paths, the system constituted by all said images being observed through a single eyepiece.

In a preferred embodiment, a concave mirror forms the common objective for both telemetric paths.

In a more complete modification, the telescope rigid with an arm and serving as a sighting glass for the latter includes in one of the telemetric paths ahead of the objective-forming mirror a group of anamorphosing prisms the magnification of which varies with the sight in accordance with a law defined by a conventional optical calculation which causes the deflection of the aiming axis in the telemetric track considered and which defines the range of the location to be observed in the field of fire to correspond to the angle of elevation equal to said sight of the fire arm rigid with the telescope.

Preferably, the achromatic group of anamorphosing prisms operating in the vicinity of the minimum deflection is constituted by three prisms cut out of a common block of glass having acute optical angles and arranged symmetrically with reference to a plane, the first prism lying to either side of said plane of symmetry while the other prisms the apical angles-of which are smaller than that of the first prism are spaced with reference to the latter in head to tail relationship with said first prism.

DRAWINGS Our invention will be better understood from inspection of the accompanying drawings illustrating an embodiment of said invention:

FIG. 1 shows the compound image formed by the telemetric telescope as seen by the observer.

FIG. 2 is a perspective diagram of an embodiment of our improved telemetric telescope.

FIG. 3 is a perspective view of a multiple prism incorporated with the diagram according to FIG. 2.

FIG. 4 is a vertical sectional view of a group of anamorphosing prisms incorporated with the diagram illustrated in FIG. 2 according to a modification of our improved telemetric telescope.

EXAMPLES OF THE INVENTION The telemetric telescope illustrated in FIG. 2 includes a first telemetric path A defined by the path of an axial luminous ray, a second telemetric path B and the actual observation telescope C, which latter are also defined by the path of the corresponding axial luminous rays.

The upper telemetric path A includes a front lens [0 beyond which the luminous rays are reflected by the total reflection prisms l1 and 12 spaced by a distance T equal to the telemet ric base as well known in the art. It is important that the reflecting surfaces of said prisms may form with each other a constant angle approximating 0 whatever may be the shocks and differences in temperature to which the telescope is submitted; this result is achieved for instance by gluing the prisms l1 and 12 on a silica support of an unvarying shape. The constancy of said angle may also be obtained by replacing both prisms by pentagonal prisms according to a further conventional solution.

Beyond the prism 12 at the input of which is located the pupil or diaphragm forming the input 32 of the upper telemetric path A, the latter reaches the objective-forming mirror I3. The latter is common to both the upper path A and the lower path B of the telemeter which tracks are still separate, although their axes lie in a common horizontal plane ahead of the objective 13. The horizontal diameter of the mirror 13 is for this reason equal to twice the span of the beams following the telemetric paths and its optical axis is shifted with reference to the medial rays of the two beams by about one quarter of the opening corresponding to its horizontal diameter. In the case illustrated although this cannot be considered as a limitation, the objective 13 forms a catadioptric system. Generally speaking, such a system has the drawback of leading to the closing off of the central part of the pupil. Now, this drawback does not appear in practice in the present case by reason of the small telemetric field inherent to our invention since as will be shown the same eyepiece collects preferably both the very reduced field of a telemeter providing a large magnification and the large field with a low magnification of the actual telescope. In contradistinction, the catadioptric ob jective shows numerous advantages such as a better correction of spherical aberrations and of chromatism than in the case of a dioptric objective for a predetermined opening and a predetermined focal length and the reflection of the beam leads to a smaller bulk for the apparatus without this requiring the incorporation of any further reflecting parts.

After reflection on said catadioptric objective 13, the upper telemetric path reaches the focal plane of said objective which is caused to lie in the vicinity of the prism 12.

In said focal plane, the path is shifted by means of a total reflection prism 14 which is positioned so that the focal plane of the objective 13 may be preferably but not of necessity located along the output surface of said prism 14.

Considering now the lower telemetric path B, it begins with the front lens 15, passes through the input diaphragm 16 located approximately in transverse registry with the prism 12, after which it impinges on the half of the catadioptric objective 13 serving for said track B, which finally reaches the focal plane of said objective 13 lying on the output surface of the total reflection prism 14.

Thus, the two field images obtained by the two telemetric paths A and B are superposed on the output surface of the prism 14. To allow seeing through the eyepiece only one of the two images in the corresponding sections 1 and 2 of the telemetric field illustrated in FIG. 1, prismatic blades 17 illus trated in FIG. 3 are located in the plane common to the two images formed on the output surface of the prism 14, said blades producinga slight deflection of the medial rays in both paths, so that the pupils in the telescopic tracks A and B may register after they have passed through said blades.

' Beyond said prismatic blades 17, both telemetric tracks pass through a common centered system comprising prisms and two groups oflenses; a diaphragm 20 is inserted at the location corresponding to an intermediate plane common to both telemetric tracks, so as to cut out completely any parasitic rays as well known in the art.

Said arrangement is designed so as to produce two erect images of the landscape or field of fire, which images are distributed between the sections 1 and 2 of the telemetric field (FIG. 1) corresponding to the two telemetric tracks A and B and are located on the output surface of the total reflection prism 21. Said latter surface corresponds to the upper section of the object field of the eyepiece 22 common to the telescope and t the telemeter and lies in principle substantially in its object focal plane.

The micrometric lines 4,7,8 are engraved on the output surface of the prism 21 at suitable locations in the section 2 of the telemetric field as shown in FIG. 1.

The sighting telescope associated with the above-described telemeter includes the above-referred to eyepiece 22 and an image-erecting objective system including the objective 23 and the erecting prism 24 which may obviously be of a type different from that illustrated in FIG. 2. Said image-erecting system provides an image of the landscape on the rear surface of the glass blade 25 which surface forms a lower extension of the output surface of the prism 21 and carries an engraved micrometric scale as illustrated in FIG. 1. Said output surface registers with the focusing plane of the eyepiece 22, in principle its focal object plane.

The positioning and centering of the output planes of the sighting telescope and of the telemeter are ensured for instance by deflecting prisms located in the focal plane of the eyepiece.

The upper section of the focal object plane of the eyepiece corresponding to the output surface of the prism 21 shows the telemetric fields 1 and 2 and underneath same on the output surface of the blade 25 there lies the field 3 of the actual telescope. It is thus possible to obtain the general appearance of the field illustrated in FIG. 1.

In said field, the lower telescopic section 3 provided with a small magnification and a large field corresponds to the actual observing or sighting telescope, while the upper section corresponds to the large magnification reduced field telemeter. One of the telemetric paths A produces an image on the area ll while the other telemetric path B forms its image on the area 2 lying to either side of the area 1 corresponding to the path A. Coincidence is to be obtained between the section 38B of the image of the target formed on the area 1 and the remainder of the image 38A of said target formed on the area 2.

In a first type of telemetric telescope, the telemetric coincidence is ensured structurally for a predetermined distance d which may be termed the fighting distance by causing the axes A and B of the object space to slope with reference to each other by a predetermined angle a equal to the parallactic angle through which the telemeter base that is the distance separating the centers of the input glasses 10 and 15 as seen at the distance to be considered. The two images of the object in the field of fire located at said fighting distance are seen as in coincidence.

This is the case for instance of the horizontal lines of the landscape located at a fighting distance.

In the simplest embodiment of our invention illustrated in FIG. 1 a reference mark constituted by a horizontal line 4 in the telemetric field corresponds to another reference mark forming the apex of the angle 5 in the observation field or field of fire. These reference marks are such that when the target lies at fighting distance, the two lower lines of the images 37 and SBA-38B of the target register respectively with the reference marks 5 and 4.

It is also possible in such very simple telemetric telescopes to include a reference mark 7 adjacent the reference mark 4. Said reference mark 7 is positioned in a manner such that the angular spacing of the object space corresponding to the spacing of said two reference marks 4 and 7 in the image plane may be equal to the difference in parallaxis of the base seen from the distances d and d. Thus, if a horizontal line of the image of the target registers in the field 2 with the reference mark 4 and in the field l with the reference mark 7, the range of said target will be exactly equal to d.

The apparatus described may also carry corresponding spaced reference marks 8 and 9,8 and 9', etc....as illustrated in FIG. 1. Each of the couples 89 or 89 corresponds to same points of the object in the fields 2 and 3 under a succession of ballistic angles of sight of the arm corresponding to different ranges higher than d. Said lines 478,8 etc....on the one hand and 5,9,9 on the other hand may form a scale of ranges.

Obviously, the telemetric diaphragms may be simplified and include only a separating line in which case each telemetric path leads to the corresponding half, the left-hand or the righthand half of the field defined by the diaphragm.

An improvement in the telemetric telescopes described hereinabove consists in providing coincidence between the images of straight horizontal lines of the object space in the sections 1 and 2 of the telemetric field exactly in registry with the sighting lines 4,8,...corresponding to distances d d,...of said horizontal lines from the telemeter.

Said improvement consists in introducing a prismatic system providing an anamorphosis of the landscape in a vertical direction. Such an optical anamorphoser may be located in either of the telemetric tracks A or B ahead of the input pupil.

FIG. 4 relates to the case where the anamorphising system 26 is inserted between the prisms 11 and 12 at a point where the telemetric path A has not yet met any convergent optical element. The selected anamorphoser constituted solely by prisms is an afocal system and it has to optically satisfy the conditions referred to in the preceding paragraph and to this end it produces through its introduction in one of the telemetric paths a modification in the magnification which becomes a function of the sight in a manner equivalent to a variable inclination for each sight with reference to the object axis in the track B. The anamorphoser is designed and positioned in a manner such that when following for instance the luminous rays starting from the ends of the lines 4,8 of the section 2 of the telemetric field in a direction opposed to the progression of the light along each of the paths A and B, there is obtained a convergence of the luminous rays at object points located ahead of the telemeter respectively at distances (1,. and d corresponding to the ranges defined by the lines 4 and 8. The convergence of said luminous rays in the object space at predetermined points of said object space is measured by the parallactic angle under which said points seek the vertical base of the telemeter. in practice, the unvarying character of the telemeter should be such that said angle may be measured with an accuracy of a magnitude of a sexagesimal second. Of course, when following a luminous ray in a direction opposed to the progression of light starting from the line 9 of the telescope micrometer, which line corresponds to the line 8 of the telemeter micrometer, there is obtained beyond the image erecting prism 24 and its objective 23 a luminous ray passing in the vicinity of the point aimed at the distance d, within the accuracy of the desired aiming. that is of a magnitude ofa few sexagesimal minutes. Thus, the association of the telemeter with the telescope need not be executed mechanically as carefully as the association between the two telemetric paths A and B.

The telemetric method which allows aiming directly a gun by giving it a sighting angle corresponding to the telemetrically measured distance after a preliminary adjustment of the axes has already formed the object as mentioned hereinabove of the prior French Pat. No. 1,1 17,609 with a different optical system.

However, in accordance with our present invention the selected anamorphising system is constituted in an original manner by three prisms 27,28 and 29 characterized by the corresponding apical angles C,D,Ev The ridges of said prisms are perpendicular to the vertical plane containing the base of the telemeter in a manner such that they may produce a cylindrical anamorphosis extending in a vertical direction. The preferred data for said anamorphiser are as follows:

the bisecting plane of the angle D of the intermediate prism 28 forms a plane ofsymmetry for the anamorphiser C=E which is a result of the preceding condition the ridges C and E are located on the side of the optical path opposed to the ridge D; in other words, the prisms 27 and 29 are set in head to tail relationship with reference to the prism 28 the empty angular space F between the prisms 27 and 28 and the empty angular space G between the prisms 27 and 29 are equal.

the three prisms 27,28 and 29 are cut out of a single block of optical glass.

a luminous ray passing through the prism 28 perpendicularly to the plane bisecting the angle D follows a path corresponding to a minimum deflection in the prismatic system considered as a whole.

The empty angular spaces F and G are selected after D and C=E have been defined, in a manner such that the whole system is substantially achromatic for the'luminous path corresponding to a minimum deflection.

This leads to the possibility of an infinite series of anamorphosers satisfying the preceding conditions for predetermined values ofD and ofC=E.

The anamorphoser to be chosen is that which is capable of producing under the best conditions an anamorphosis such that when following a direction opposed to the progression of the luminous rays, a bundle of planes adapted to be superposed over the bundle of the planes P4,P5,P8,...passing through the optical center of the objective l3 and the horizontal lines 4,8,...defining the sights in its focal plane may be transformed into a bundle of planes P'4,P'8,...which is closer while any two planes P4,P8 for instance form with each other an angle P4, P'8 equal to the angle P4,P8 ininus the difference between the parallactic angles under which the verti- LII cal base of the telemeter is seen from the points 0c, Oi of the object space corresponding to the sights defined by said lines 4 and 8.

The anamorphoser being thus selected, its angular setting is adjusted with reference to an axis parallel with the ridges of the prisms so that said setting with reference to the bundle of planes P4,P8 produces the precedingly defined anamorphosis. Said angular setting is always very near that which causes the luminous rays following the telemetric path to pass in the vicinity of the path corresponding to a minimum deflection.

Finally, the prism 11 is rocked by a small amount so as to produce through a general shifting of the planes in the direction opposed to the direction of the light, the suitable convergence of the luminous rays which have passed along the two telemetric paths through object points Oc,Oi as disclosed hereinabove.

The advantages of said prismatic anamorphoser are as follows:

it allows comparatively large modifications in the anamorphosing magnification as provided by the large angles of incidence of the luminous rays while said magnification remains approximately equal to l for minimum deflection conditions the possibility of obtaining said modifications in the anamorphotic magnification associated with the possibility of interpolating numerous solutions depending on the initial selection of the two parameters D and C=E lead to an anamorphotic law which matches suitably the law defining the angles of elevation of the arm as functions of range within the scale of ranges selected say between 200 and 600 meters the possibility of keeping a magnification approximating unity allows providing for the two telemetric tracks juxtaposed objectives of same focal length or even a common objective-forming mirror, as disclosed, which ensures the unvarying adjustment ofthe telemetric structure defining materially the telemetric base lastly, there is obtained through the inverted arrangement of the prisms having the same index of refraction a substantially complete correction of the apparent primary and secondary chromatism which would otherwise act detrimentally on the accuracy of the telemeter.

It is apparent that the optical system associated with the arm allows:

watching the firing field in front of the arm for which an optical system with a large field is required an estimation of distance with a suitable accuracy i.e. with a sufficient telemetric power a laying with one or more reference marks carried by the spider lines of the telescope for predetermined ballistic angles of sight.

It is of advantage to provide an apparatus with a sufficiently small bulk for it to be permanently secured on the fire arm without it being necessary to fold or dismantle the telemetric structure.

It is also of advantage to execute in a substantially simultaneous manner the telemeter and laying operations:

either in the case of a grazing fire executed with an unvarying sight or fighting sight for which the marksman must make sure that the distance of the target is not greater than the maximum distance defined by regulation or else, in the more general case, of a direct firing executed with a varying sight according to opportunity taking into account the distance at which the target is estimated.

The optical systems known hitherto and associated with infantry arms used for direct firing do not provide such combined possibilities.

In contradistinction, our improved type of apparatus is designed so as to allow:

watching the field of fire of the arm the simultaneous execution of telemetric and aiming operations in particular when firing with a fighting sight the permanent transportation of the apparatus on the arm without any folding or dismantling of the telemetric structure. The starting points of the invention are as follows: it is sufficient to provide a very broad field with a moderate magnification for it to be possible to watch the field of-fire for telemetric purposes, a narrow field is sufficient if the aiming has been first made in a rough manner with the ac tual telescope the small bulk requires a short telemetric base and consequently a large magnification for the telemeter in order to obtain a sufficient telemetric power.

Three types of apparatus have thus been designed starting from such principles:

firstly a simplified apparatus adapted to produce a single telemetric result and characterized by a harmonious association of two telemetric tracks for a single range, in principle the maximum range d of firing with a fighting sight, which range is associated in the telescope with a ballistic sighting reference mark which may be a single mark or a main mark secondly an apparatus directly derived from the preceding one and adapted to provide two telemetric results, in which apparatus the telemetric tracks are harmonized for a single first range, in principle the maximum range 11,. of firing with a fighting sight, while it allows furthermore comparing the difference in parallaxis between the images of the target seen through the two telemetric paths, with the parallactic spacing corresponding to a second range d slightly greater in principle than d thirdly, a more intricate apparatus providing a multiplicity of telemetric data and ensuring, in proximity with each of a number of sighting reference marks, a correspondence between the telemetric data and the ballistic sighting angle, which result is obtained with the system of prisms referred to hereinabove.

For the execution of an arm incorporating optical apparatus of any of the three above-disclosed types, the marksman should:

observe the target or the point of passage to be watched on the area 3 of the eyepiece provide a rough aiming by resorting to the reference mark finish the aiming by resorting to the reference mark 4 while examining the coincidence between the horizontal lines in the vicinity of last-mentioned reference mark in the fields it and 2, said telemetric observation being executed without any substantial further delay.

When the comparison between the horizontal lines is satisfactory the marksman may fire immediately by making the reference mark 4 for instance corresponding to a fighting sight register either with the lower part of the target or with its center. Otherwise, the marksman attempts firing by resorting to one of the reference marks 8 corresponding to the range he has to estimate.

More particularly, in the case of apparatus of the third type referred to, the marksman resort to the reference mark 8 in the vicinity of which coincidence is obtained between the horizontal lines in the two telemetric areas 1 and 2. When said telemetric operation has been executed the marksman can:

when firing on a target, he may aim at it by resorting to the reference mark 8, said aiming operation being performed almost without any further delay or else, if it is desired to watch a point of compulsory passage, he notes the reference line 9 corresponding to the abovementioned reference mark 8.

We claim:

1. A telemetric telescope comprising means defining two optical paths including an objective common to said two paths and an eyepiece common to said two paths with the lines of sight of the two paths vertically spaced apart and converging and crossing each other a predetermined distance forwardly of the telescope, means to dispose the images along said two paths viewed through said common eyepiece in register with each other vertically at said predetermined distance and vertically displaced from each other at distances other than said predetermined distance, a further objective so disposed as to form a further image of the sighted object in the focal plane of said common eyepiece, the image formed by said further objective being substantially smaller than the images formed by said first-mentioned objective, at least two fixed reference marks, and means for forming in said focal plane of the eyepiece images of said fixed reference marks one of which occupies the same position relative to one of the images along said two paths as does the other reference mark image relative to said further image,

2. A telemetric telescope as claimed in claim 1, in which said common objective is a concave mirror whose surface is intersected by said paths at laterally spaced locations.

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