US3057258A - Still camera lens attachment - Google Patents

Description

Oct. 9, 1962 A. S. MILINOWSKI, JR., ETAL STILL CAMERA LENS ATTACHMENT Filed July '7, 1960 2 Sheets-Sheet 1 lim Edward Eloyd de Cariky BY Fe/)fwn Fsk Oct. 9, 1962 A. s. MlLlNowsKl, JR., ETAL 3,057,258

STILL CAMERA LENS ATTACHMENT 2 Sheets-Sheet 2 Filed July 7, 1960 f. 04 Jv, f www W jmzrk OSafS W j Twcl.. N C 1 E0 F .LVMH- ,W 1.2% uw WLM M/ 2 7 S 9 ,.0 ndm/ l vri a@ a au Novlws T AEW HTTRNY STiiiji CAMERA LENS ATTACEMENT Arthur S. Miiinowsiri, lr., Nerv/alli, and Edward L.

This invention relates to a still camera attachment usable in an airplane for the purpose of combining images from a sight reticle of the cross hair or concentric circle type and a gunnery practice target. That is, the invention is intended to combine the image of a reflex sight reticle and that of a plane which is to be shot down by practice fire, so that the actual guns are not fired, but where instead a picture or a series of pictures of the target and the reticle are taken in order to determine Whether or not the student gunner has in fact aligned the target and his gun.

During peace time there exists the problem of keeping military pilots and gunners in practice as to shooting down what would be, in war-time, enemy planes. Of course, in peace time no such targets exist, and a substitute means such as a camera must be used in place of the cannon or machine guns which would normally be used in War-time in order to provide the practice and the training necessary for the pilot and/ or gunner to become and stay proficient in shooting down enemy planes when the real occasion arises.

Generally a practice camera is used in such a manner that a picture of the target and the sight are taken in order to record what the actual relationship of the target and the gunners or pilots sighting means Were at the time the operator pulled the trigger of what would be in War-time an actual rocket tiring mechanism, cannon or machine-gun. Thus, a record of Whether or not the operators firearm actually was on target, at the time that he decided it Was in fact so, is preserved so that both both his instructors and superiors may determine his proliciency and also so that the gunner or pilot himself may determine in What manner his firing is inaccurate.

In planes of the pursuit or tighter type, the usual sighting means is a so-called reex sight, that is, the type of sight in which the reticle is projected at infinity indirectly into the eyes of the pilot, so that the pilot may see in the same plane, i.e., at optical infinity, both the target that he is firing at and the reticle of the sight. In such type of planes the gunner is, of course, the pilot himself and the sole means usually used for aligning the firearms of the pursuit plane and its target is reorientation of the Whole plane so that the planes axis is pointing at the target.

Since the pilots job in a fighter plane is then basically to align the axis of his plane (and therefore the axis of the rockets, cannon or machine-guns carried thereby) with the target, typically the type of sight is a center reticle sight; that is, that type of sight which marks either by concentric circles or cross hairs, the center line or axis of the plane. Because this sight is of the reflex type, the actual reticle is not seen directly by the pilot but, on the contrary, is actually projected into the pilots eyes through an optical system, of which the reticle is at the focal point, so that the reticle itself is seen as if it were at optical infinity. When the axis of the plane as determined by the center of this projected reticle and the target which the pilot intends to shoot-down are aligned, the pilot of course would normally fire the rockets, machine gun or cannon mounted in his plane thus to bring down the enemy.

yIn order to adapt such a system to training and refresher practice type of operation, a means must be provided to Cil 3,057,258 Patented Oct. 9, 1962 combine the target and the reticle image in the same relationship as normally seen by the pilot and to record these permanently on a photographic film. Combining these images and keeping both the target and reticle images in exactly the same optical and apparent spatial relationship as they would appear to the pilot is a problem, which is difficult to solve, since not only is precise optical alignment of the sight, camera and pilots line of vision required, but also because such a system must be capable of withstanding the high inertial loads sustained by a modern pursuit plane in flight. That is, such a system must not only be optically true when it is installed, but it must remain so after repeated landings and take-off, or at least be capable of adjustment to be once again accurate with only a reasonable amount of maintenance.

Further, such an apparatus must be quite small in order to fit into the already cramped cockpit of a modern fighter plane of the jet type. The present invention is directed to such an apparatus and accomplishes a specific solution to an extremely difficult technical problem by comparatively straight-forward and therefore easily adjustable optical means. In accordance with the invention, an optical system having the general properties of a telescopic periscope but of quite small dimensions and an extremely high precision (as to alignment of the images therein and to resolution ability of the optical system) is provided for the purpose fully described above.

Although the specific system illustrated in the accompanying drawing and described hereinafter in detail is intended for an F104 fighter plane, the invention is of course not limited to such a specific embodiment but on the contrary is only exemplified by the disclosed specific optical system and mounting means therefor hereinafter fully disclosed. The general problem which the invention solves is rather the provision of an optical system of high precision, which can combine very accurately and with virtually no angular error, two images (i.e., the target and the reticle image) along a reference line (i.e., the pilots vision line) without obstructing the pilots view and Without impeding in any manner the operation of the reticle sight and further enabling a picture to be made of the exact orientation of the rellex reticle sight and the target at the time that the pilot decides he is in fact on target and therefore shoots An object of the invention is therefore to provide a camera attachment for combining the images from a reticle and from a target so that a photograph of this combined field of view may be taken.

Another object of the invention is to provide a device of the above type which is very compact so that it does not interfere with the normal line of View of the adjacently seated pilot.

A further object is the provision of a device having not only an accurate optical system which is carefully aligned so that the reticle and target images are kept in the same relationship as they were originally seen by the pilot, but also one which is comparatively strong mechanically so that the system does not go out of adjustment upon use and exposure to extreme inertial loads of acceleration and deceleration type.

Another object of the invention is the provision of a device of the above type which is not only small in those parts which interfere with the pilots line of view but is also small in overall dimension, that is, does not occupy too much general space of the cockpit so that it does not interfere with the other controls of the cockpit or any part of the pilots body.

A further object of the invention is to provide a device of the type described above in which there is an economy of optical elements, mechanical mounting means, and in which the number of precision parts necessary to establish and maintain precise optical alignment of the enclosed parts is kept to a minimum, thereby making the manufacture and maintenance of the instrument comparatively inexpensive for the precision desired. Y

Other objects and advantages of the invention will be obvious to one skilled in the art upon reading the fo-llowing specification and upon studying the accompanying drawing, in which:

FIG. 1 is a side view, part elevational and part sectional, of the camera attachment, also showing the general arrangement ofl the reflex sight assembly and the combining glass used for combining the image thereof with the pilots line of View;

FIG. 2 is a rear elevational view of the attachment which forms the subject matter of the invention;

FIG. 3 is a schematic optical diagram of the elements in the periscope taken from the rear, i.e., looking in the same direction as the pilot would be in the aeroplane in which it is used;

FIG. 4 is a plan schematic optical diagram of the optical system, that is, looking down from the top of FIG. 3.

Although the invention is not limited by the specific embodiment shown and hereinafter described, nevertheless, in order to comply with the patent statutes, a specific structural embodiment is shown and described in detail.

Referring to FIGS. l and 2, the existing reflex reticle sight supports, by circular mounting flange 12 and mounting bracket 13, the camera attachment generally shown at 14. The camera attachment generally comprises a pri-sm mounting head assembly 16, an objective tube `18, and an elbow tube 20. Suitable attaching means,

such as screws 22, are used to attach these last two mentioned tubular assemblies together. Connected to the end of elbow tube 20, which is remote from objective rtube 18, is the second objective tube 24, which in turn is connected to the camera lens tube 26. At the right- =hand end ofthe camera tube 26 (see FIG. 2), the camera 200 used with the attachment is connectedr thereto such that the film plane -thereof lies below the extreme righthand end of said tube 26. Combining glass 30 is so arranged (see FIG. l) that the image reflected by reflex sight 10 is reflected by plate 30 into the left-hand surface 32 of prism head assembly 16. The light rays from the reticle follow the path 34 upward, are reflected from right side 36 of plate 30, and then follow the path 38 to so reach the prism head assembly 16.

FIGURE 3 shows more clearly the path of light through the camera attachment and shows the optical elemen-ts lcontained therein. No .attempt has been made to show the exact internal mounting of these elements since any conventional means may be used.

The light entering the prism housing head |16 along path 38' is reflected by prism 40 such that it is deviated in a downward direction along path 46 to first lens group 50 of the first objective lens assembly, thence to second lens group 60, and then to right-angle prism 68. This right-angle prism reflects the light rays to the right as seen in FIG. 2 to the third group 70 of the second objective lens assembly, then to prism and lens assembly 150 (see FIGS. 3 and 4). This prism and lens assembly 150 is composed of prisms 154 and 172, first group 160 of the second objective lens, Petzval curve corrector 80, and third group 90 of the second objective lens. The rays then enter the final prism and lens assembly 100 which is generally comprised of right-angle prism 100 and the camera lens assembly 110.

In detail, the optical system generally just described is comprised as follows. Prism 40 is of the single-reflecting type and its general shape is best seen in FIG. l. The first group 50 of the first objective lens assembly is composed of double convex lens element 52, negative meniscus lens 54 cemented thereto, air space 56, and nearly plano-convex lens 58. The first objective Petzval curve corrector 60 is of little dioptric power and is composed of first Petzval corrector 62, air space 64, and second 1 Petzval lens element 66. After being reflected by the right-angle prism 68, the rays encounter lens element 72 of the third group of the first objective 4lens assembly, pass therethrough and then through air space 74, meniscus concave lens element 76 and then double convex lens 78.

The rays then enter the lefthand surface 152 of Abbe prism 154, are reflected upward (see FIG. 3) by surface 153 along line 155 and then strike surface 156. This surface 156 is angled (at 45 to the plane of the paper in FIG. 3 in such rela-tionship as to reflect verticle rays 155 directly into the plane of the paper as seen in FIG. 3 (and therefore apparently upward in the plan view of FIG. 4). The rays then encounter the first element 162 of the rst group 160 of the second objective lens assembly (see FIG. 4).

After passing through the first double convex element 162 of said first group, the rays then pass through the second element, concave meniscus lens 164, air space 166, and then the third and last element, almost plano-convex element 168 of said first group 160 of the second objective. Emerging from this group, the rays are reflected by right-angle prism 174 to the second Petzval curve corrector 80, which is comprised of rst Petzval element 84, air space 86, and second Petzval element 88. The rays then encounter the third group of the second objective assembly, which comprises plano-convex lens 92, air space 94, and a doublet consisting of a negative meniscus lens element 96 andthe double convex last element 98.

The rays emerging from this second objective lens assembly are then refiected by right-angle prism to the final lens assembly 110, which acts as the objective lens of the camera 200, see FIG. 2. The camera objective is composed of first plano-convex lens 102, large air space 104, double concave lens element 106 and, separated therefrom by air space 107, plano-convex lens 108. The diaphragm of the camera lens itself is schematically shown at and actually passes 4through air space 107; and the film plane, which of course has the final image projected thereon by the optical system, is shown sche,- matically at 130.

The general koperation of the system will now be explained. Referring-back to FIG. 2, the operator of the pursuit airplane, i.e., the pilot, sits with his eyes essentially level (in the horizontal plane) with the left top of the camera attachment (that is, in the neighborhood of the prism head assembly 16; but, of course, with one eye t'o the left and one eye to the right of the prism head). In this position, the pilot will see the target through the `combining glass plate 36 and at the same time will see projected upon this combining glass an image of the reticle of the reflex sight. At such time as the operator believes that the project reticle and the target are lined up, he will press a trigger (which would in war-time fire a rocket, a cannon or a set of machine guns). In training the effect of firing this trigger is only to take the picture of the scene seen by the pilot at the time that he decided that he should fire The above-described attachment accomplishes the purpose of bringing to the film plane in the camera both the -imagesy of the target and the image of the projected reflex 4sight reticle as seen by the pilot at the exact time that the pilot considered himself ina position to make a kilL As previously explained, the manner of accomplishing this purpose is -to unite, by means of the combining glass 36, the reticle of the reflex sight projected along line 34 (sce FIG. l) and then along line 38 into the camera attachment proper. Since the optical system must keep both the reflected reticle image and `the. more direct image ofv the target (iLe., the enemy plane) always coincident, the optical system must not only be aligned with `the pilots normal line of view but also must be so designed that it maintains this relationship despite relatively high inertia-l loads impressed upon the camera attachment by the acceleration and Ideceleration of the plane.

This is accomplished by the invention as will be explained below in connection with the operation of the optical system itself.

In FIG. 1, the reflex sight 10, projects as parallel rays 34 (i.e., at optical infinity) an image of the reticle, which is then reflected by combining glass 3ft into the prism head 16 through window 32. These parallel rays are reected by the single-reliecting surface 42 of prism 4t) to emerge at the lower face of the prism along path 46. These parallel rays then encounter and are converged by the first group of the first objective lens (i.e., lens elements 52, 54 and 58 and air space 56) to a focus at the first image plane Il. The first Petzval corrector element 62 assists in making the Petzval sum of the first half of the first lens assembly (i.e., lens group 50 and corrector 62) a minimum, thereby making the lens anastigmatic, i.e., yielding a fiat-field image.

This image of the reticle, I1, is at the first focal point of the third group 7l) of the first objective lens assembly, taking into account the effect of the second Petzval corrector 66. In other words, lens elements 66, 72, 76 and 78 and air space 74 are of such curvatures and spacing that the image formed at I1 is at the focal point of this part of the lens system. Therefore the light emerging from the right-hand surface (see FIG. 3) of the last element 7S is parallel once more. It should be noted that the right-angle prism 68, although of course deviating the light rays 9() degrees, does not affect in any substantial manner the dioptric effect of the second Petzval element and the third group of the first objective lens assembly.

rThe parallel rays emerging from last element 78 then enter left-hald surface 152 of Abbe prism 154, are refiected upwardly by surface 153 thereof to strike surface 156 so that the rays then travel into the paper as seen in FIG. 3. These parallel rays, now traveling along line 157 in FIG. 4 are then converged by the first group ( elements 162, 164 and 16S and air space 166) of the second lens assembly and strike the refiecting surface 172 of the right-angle prism 174, thereby being reflected to the right (as seen at FIG. 4). The rays are slightly refracted as they pass through the first Petzval curve corrector element 84, and come to a focus in the second image plane I2.

As in the case with the second half of the first objective system, the second half of the second objective system is also so positioned relative to image plane I2 that the rays eventually emerging from the last element of this half-lens system are also parallel. In other words, the image plan-e I2 is at the first focal plane of the combined optical elements 88, 92, 96 and 98, including air space 94. The parallel rays finally emerging from the right-hand surface of the last lens element 98 are parallel as they enter right-angle prism 100 (see FIG. 3). These parallel rays carrying the image of the refiex sight reticle are then finally focused onto the film plane 130 by means of the camera objective lens assembly 110. Therefore, the focal point of this camera objective, composed of lens elements 102, 106, and 10S and air space 104, previously described, coincides with the film at the film plane 130.

Thus a permanent photographic image of the reticle is placed upon the film in the camera by means of the optical system of invention.

The two objective lens assemblies are quite similar, and each is almost symmetrical through its respective image planes, Il and I2. In fact, the first lens system ( groups 50, 60, and 70) has a magnification power of unity (and is perfectly symmetrical), although the second lens assembly (groups 16), 180 and 196) has a magnification power of 1.4 and is, therefore, obviously not symmetrical. Therefore, the number of different types of lens elements (and lens groups) needed to be manufactured is kept to a minimum.

Since the optical path of the image rays from the target (i.e., the/enemy plane) is substantially the same as that of the reticle of the reflex sight, such path will not be described in detail, but rather only the differences between the two paths are hereinafter described. Entering light rays 32', carrying an image of the enemy plane, enter the cockpit of the fighter plane and encounter first left-hand surface 35 of the combining glass 3f). The rays 32', though slightlyy refracted by this surface 35, proceed in a slightly deviated straight line 33 through the glass and out the right-hand side 36 of the combining glass plate as rays 37, optically aligned with the rays 38 from the reticle sight which have been reflected by the same right-hand surface 36. Since the target is, of course, at a great distance away from the combining glass, the enemy plane is in effect an optical infinity so that the light rays from both the reticle of the reflex sight and the target are parallel and therefore are treated by the rest of the optical system (to the right of the combining glass) in the same manner, both in alignment and in dioptric convergence.

The disclosed camera attachment therefore makes it possible to align both of these images in an optically true manner without any unnecessary elements, adjustments, or mechanical complications. The sole optical adjustments are accomplished by having the first single-reflecting surface prism 46 mounted in an adjustable manner. In order to accomplish vertical or elevation adjustment, adjustment plate 182 which determines the angular position of the prism 40 is pivotally mounted about axis 184; and adjustment screws 186, 188 are provided for pivoting this plate. By tightening one of the adjustment screws and loosening the other, the prism 4f! is thereby rotated by a small, precise amount about axis 184 (i.e., perpendicular to the paper in FIG. l) thus enabling the installation and adjustment of the camera attachment. This adjustment centers the optical axis of the rest of the optical system with the images of the target and the reflex sight reticle in the vertical plane. Similarly, should the mechanical elements of the system become dislodged because of vibration or inertial loads, caused by the operation of the plane or other causes, the prism adjustment enables the maintenance crew to re-adjust the system so that the target and the reticle sight images are once again made to coincide with the optical axis of the whole camera attachment.

In order to enable adjustment of the line of sight in the horizontal plane (see FIGS. l and 2), the prism head assembly is preferably mounted so that it is rotatably adjustable about a Vertical axis. Therefore, prism head assembly 16 is rotatable with respect to first objective tube 18 about the vertical aXis thereof. Since it is, of course, necessary to maintain the prism head in one specific position, once the initial adjustment has been made, set screw (see FIG. 2) is provided to clamp the prism head firmly in the correct position about this vertical axis.

The initial adjustment of the correct sight picture to be seen by the pilot is made by slight rotation of the combining glass 30 about its center along a horizontal axis perpendicular to the plane of the paper in FIG. l. The effect of such rotation is to deviate through an angle, twice that of the rotation, the reticle rays 38 which have been reflected thereby; but this rotation displaces the target rays 33, 37 only a slight amount. Therefore, the reflex sight reticle image (see ray 38) can be reoriented so that it precisely represents the axis of the firearms intended to be used therewith, without this substantially changing the position of the target image. For this adjustment, means (not shown) similar to that used to pivotably mount prism 40 are utilized.

Since both mechanical rigidity and optical alignment are important, in fact, crucial, to the operation of the entire system, circular mounting flange 12 is so shaped as to make good mechanical contact with the top of the reticle sight 10. (See FIG. 1.) Further, mounting bracket 13 is provided with a large number of attaching screws, arranged in groups 192, 194 and 198. As

eresmas shown in FIG. 2, the camera 200 is also firmly mounted to the camera attachment, thereby affecting a good mechanical connection and thus a true optical alignment. Screw 202 (FIG. 2) and screw 214 are venting port cover screws. In order to firmly attach the elbow part of the mounting tube of the camera attachment to stationary parts of the cockpit of the airplane, a second mounting bracket 210 (see FIG. l) provided with attaching bolts 212 are provided at the. lower part of this elbow tube 20. Set screw 214 (see FIG. 2) is provided to hold tubes 18 and 20 firmly together, as do screws 220 with respect to tubes 24 and 26.

The invention therefore accomplishes the` desired results set out in the above objects, of providing a strong, precise, comparatively easily manufactured, and readily adjusted optical instrument for relaying the images (as seen by the pilot) of the reticle in the reflex sight and the target onto a photographic film; and this is accomplished without any unnecessary waste of space in the cramped quarters of the modern pursuit plane cockpit. Further, no interference with the pilots normal sight is caused by use of this device.

Of course, a motion picture camera (with a similar lens) may be substituted for the still camera box (200) and lens (110) disclosed, especially since the camera lens is really not a part of attachment itself. Similarly other changes and modifications of the disclosed embodiment will be obvious to one skilled in the art upon seeing this disclosure, and this patent is intended to encompass all such changes. Therefore, the invention is not limited to the disclosed embodiment, but rather is defined in the appended claims and their equivalents.

We claim:

1. A camera attachment for relaying at least one image from at least one distant object to a remotely located film plane inside a light-tight still camera box, comprising:

a first reecting element 40 positioned so as to receive and redirect the parallel rays emanating from such distant object, said received and redirected rays determining a first plane;

a first achromatic positive lens group 50 in said redirected parallel rays for focusing said parallel rays t a first image at a rst image plane I1;

a first Petzval curve corrector element 62 positioned between said first group and said first image, for reducing the Petzval sum of said first lens group, to thereby render said image flat at said image plane;

a secondkPetzval curve corrector element 66 and a second positive achromatic lens group 70 positioned on the side of said first image remote from said first lens group, andv at such distance that said first "image is at the principal focal plane thereof, the rays from said image plane thereby being rendered parallel once again;

both said first and second Petzval curve corrector elements, on the one hand, and said first and second lens groups, on the other hand, being symmetrically arranged about said first image plane and being identical;

a second reflecting element 68 positioned between said second Petzval curve corrector element and said second positive achromatic lens group, saidk second reflecting element being disposed to redirect the rays perpendicular to said first plane;

a third reflecting element 153 positioned to receive and redirect the rays from the second positive achromatic lens group, said received and redirected rays from the third reflecting element determining a second plane;

a fourth reflecting element 156 positioned to receive and redirect rays in a direction perpendicular to said second plane;

a third positive lens group 160l and a third Petzval corrector element 84 positioned in the parallel rays emanating from said second positive group to focus said rays to a second image and to make said image anastigmatic respectively;

a fourth Petzval corrector element 8S and a fourth positive lens group positioned with their focal point at said second image plane thereby to render again parallel the image carrying rays from said second image;

said third and fourth lens groups, on the one hand, and said third and fourth Petzval correctors, on the other hand, being symmetrically arranged about the image plane;

and a camera objective lens positioned in the parallel rays emerging from said fourth lens group so that said rays are focused at a third and final real image at the film plane.

2. Apparatus as definedin claim 1 including first mount.- ing means for rigidly mounting the attachment to adjacent structural members and second mounting means for connecting the attachment to a camera to be used therewith.

Davies et al. May 5, 1959 Baker Aug. 18, 1959

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