US3191305A - Sighting device - Google Patents

Description

SEARCH ROOM 33-242. Cm 2,191.305 June 29, 1965 e. R. GAMERTSFELDER 3, 91,30

SIGHTING DEVICE Filed Nov. 29. 1961 4 Sheets-Sheet l I NVEN TOR. GEORGE R. GAMERTSFELDER ATTORNEY J1me 1965 a. R. GAMERTSFELDER 3,191,305

SIGHTING DEVICE 4 Sheets-Sheet 2 Filed Nov. 29. 1961 ATTORNEY Jun 29; 1 65 e. R. GAMERTSFELDER 9 ,30

SIGHTING DEVICE 4 Sheets-Sheet 3 Filed Nov. 29. 1961 INVENTOR.

GEORGE R. GAMERTSFELDER ayy/7ya ATTORNEY ,1965 G. R. GAMERTSFELDER 3,191,305

SIGHTING DEVICE Filed Nov. 29. 1961 4 Sheets-Sheet 4 INVEN TOR.

GEORGE R. GAMERTSFELDER ATTORNEY United States Patent 3,191,305 SIGHTING DEVICE George R. Gamertsfelder, Pleasantville, N.Y., assignor to General Precision, Inc., a corporation of Delaware Filed Nov. 29, 1961, Ser. No. 155,705 7 Claims. (CI. 3347) This invention relates to sighting devices for aiming by eye at a selected object.

Sighting devices are widely used on ordnance and on surveying, astronomical and nautical instruments. The simpler sighting devices include the open and peep sights of rifles, the rib and bead of shotguns, the iron sights used on some machine guns, and the marine pelorus. For more accurate sighting and for collimation to avoid parallax error, low-power telescopes containing cross-hair reticles are sometimes employed for these uses and others, such as by surveyors in the transit and by astronomers in the finding telescope.

The present invention provides an improved sighting device for these uses. It combines advantages of the open sight While it provides the collimating eflect of the telescopic sight, but with a wider field of view. Like the telescopic sight, the present invention places the reticle, in appearance, at infinity on the axis of the sight. An unique advantage of the sight of the present invention over both the open and the telescopic sight is that it may be made as large, transversely, as desired, within the limit of permitted transverse displacement error. That is, while the telescopic sight exit pupil is, ideally, of the same diameter as the pupil of the users eye, and to that extent restricts transverse movements of the users head, the present sight may if desired be made an inch or more in diameter, so that freedom is given for large sidewise displacements of the eye of the user.

A disadvantage of open sights, such as the front and rear sights of a rifle or pistol, is that one or the other of the rifle or pistol sights or the target may appear blurred. The present invention overcomes this difficulty because the eye does not focus on the elements of the sight but only on the target. A disadvantage of telescopic sights is that, in order to eliminate parallax completely, they must be adjusted at each target distance so that an image of the target falls exactly on a reticle. The present invention overcomes this difliculty since it involves no refractive optics and no intermediate images.

The sighting device of this invention occupies a space defined by the surface of a prism or cylinder with its axis in the direction of the line of sight between the eye and the target object. The prism or cylinder is bounded at its two ends by planes which generally are at right angles to the axis. The space is partly occupied by opaque, or partly opaque, elements so arranged that the light transmitted in a direction parallel to the axis, or in certain selected directions related thereto in a specified way, in less than the light transmitted in any oher arbitrary direction. Hence, rays from a distant point on the axis of the sight are highly attenuated. These rays pass through the sight as a bundle of rays parallel to the axis and are brought to a focus on the retina of the user. Conversely, rays from distant points not on the axis, passing through the sight as bundles of rays not parallel to the axis and focused on the retina, are not as highly attenuated. The user thus sees a dark spot superimposed on that point of the field which lies on the axis of the sight.

In another embodiment the opaque, or partly opaque, elements are so arranged that the light transmitted in a direction parallel to the axis, or in certain selected directions related thereto in a specified way, is more than the light transmitted in any other arbitrary direction. Thus rays parallel to the axis are less highly attenuated, in

Patented June 29, 1965 general, than any other rays and the user sees a light axial spot superimposed on a darker field.

The principal object of this invention is to provide a simple, lensless, collimating sighting device.

Another object of this invention is to provide a sighting device which is as simple as an open sight but which has many of the advantages of a telescopic sight.

Another object of this invention is to provide a collimating sight containing no refractive optical elements but containing elements having various degrees of opacity, such elements being so placed that the light transmission in a preferred direction is either less or more than in all or most other directions, as the case may be.

A further understanding of this invention may be secured from the detailed description and associated drawings, in which:

FIGURES 1 and 2 are side and end views of a form of sighting device embodying the invention.

FIGURE 3 is an isometric view of the inside of a sighting device indicating a method of generating multiplane elements for use with the sight of FIGURES 1 and 2.

FIGURES 4, 5, 6 and 7 are patterns for use in a fourplane sight similar to that shown in FIGURES l and 2.

FIGURE 8 illustrates the reticle image formed by the four patterns of FIGURES 4, 5, 6 and 7 when employed in a multiplane sighting device.

FIGURES 9 and 10 are the positive and negative of a pattern of small circular areas randomly placed for use in a two-plane sighting device to produce an opaque round dot reticle.

FIGURE 11 is an optical diagram illustrating the use of a two-plane sighting device.

FIGURE 12 is a positive pattern similar to that of FIGURE 9 except that the individual circular areas are smaller.

FIGURE 13 is a pattern having elements consisting of crosses and having the pattern of their placements the same as that of FIGURE 10.

An embodiment of this invention employs a space in the form of a right circular cylinder with the opaque elements distributed throughout the volume. The external appearance of such a cylindrical sighting device is shown in FIGURES l and 2. The cylinder 11 is mounted by means of its base 12 and screw holes 13 and 14 on the receiver of a rifle or other device to be sighted. The cylinder contains a plurality of glass discs, four of which are indicated by the dashed lines, 16, in a spaced apart parallel configuration. One side of each disc contains a pattern of opaque elements applied thereto by a photographic process. The appearance to an eye, at position 17, of the cylinder and its contained transparencies 16 is indicated in FIGURE 2 except for the patterns, which are not shown.

A method of developing the patterns is indicated in FIGURE 3, which shows a prismatic space with square ends 18 and 19. Twenty-two opaque elements such as element 20 have approximately the same area, each area being a small fraction of the cross-sectional area of the cylinder. These elements may be irregular, as shown, and varying randomly in both shape and area or they may be regular in shape and either vary in area or have the same area. In FIGURE 3, all of the opaque elements were generated by dividing the end plane 18 into elements having random shapes, then moving the elements by randomly selected distances to or toward the other end plane '19, .the movements all being parallel to the axis. In the illustration of FIGURE 3 two elements were moved to the end plane 19, and 20 elements were moved to 20 different intermediate planes. Thus these 20 planes, together with the end planes, would be represented in FIGURE 1 by one surface of each of 22 glass discs such as discs 16. In each transverse plane containing one or more elements the pattern is a random one, but is related to the patterns on the other planes in such a way that the projection of the areas of the totality of opaque element-s onto a plane perpendicular to the axis of the cylinder or prism just fills the entire cross-sectional area. Therefore, in a direction parallel to the axis of the cylinder or prism the optical transmissivity is zero. In any other direction sufliciently different from the axial direction, the patterns in the several planes will, owing to their random nature, appear unrelated, and in these directions the total transmissivity will be simply the product of the transmissivities of the individual discs or planes. in each case this transmissivity is just the fraction of the tot-a1 area of the plane which is transparent.

For example, if there be three discs in the sight of FIGURES 1 and 2, each having one-third of its area opaque, the transmissivity of each disc will be /3 and the total transmissivity in other than the axial direction will be /s /2.= If there be a number, n, of discs each having a fraction l/n of its area opaque, the total transmissivity in an oblique direction will be (l-l/n) which, if n be large, approaches the value 1/ e, where e is the Napierian base.

An observer looking through this sight will see a scene or object at a reduced brightness, with a blank spot superimposed on it at the point where the scene or object is intersected by the axis of the cylinder.

FIGURES 4, 5, 6 and 7 illustrate another way of composing a multiplane pattern for use in the sight of FIG- URES 1 and 2. Each of these four figures is composed of short vertical and horizontal lines so placed that if all of them should be projected on one plane they would fit together to form an opaque disc.

The apparent size of the black reticle image in the case of either of these patterns is determined by the departure from the axial direction required for the patterns on the several discs to become uncorrelated, which in turn depends upon the sizes of the individual opaque elements and upon the separations of the discs. The angular spread, or size of the black spot, will decrease as the sizes of the opaque elements are reduced and will decrease as the separations of the discs are increased.

The lateral extent of the opaque elements may be made larger in certain preferred transverse directions which will give rise to a spot which itself is of greater angular spread in these same preferred directions. For example, the elements of the four patterns on FIGURES 4, 5, 6 and 7 have generally greater extent in the vertical and horizontal directions and will produce a reticle spot in the shape of a cross as shown in FIGURE 8.

It is not required that the projection of the areas of the opaque elements onto a plane perpendicular to the axis completely fill the cross-section, but only that these projections be essentially non-overlapping. Thus, the total area of all of the opaque elements contributes to the attenuation of light energy travelling parallel to the axis, whereas in oblique directions a large measure of overlapping of the opaque elements occurs and only a fraction of the total area of the opaque elements is effective in attenuating the light energy. By making the total area of the opaque elements less than the cross-sectional .area of the cylinder or prism, the overall light transmission of the sight is increased at the expense of making the spot or reticle less dense. This may be desirable for applications involving a low level of illumination.

A particularly simple arrangement results if only two discs, or pattern planes, are used. If the projected areas of the opaque elements fill the cross-section of the cylinder or prism completely, the patterns on the two discs or planes must of necessity be complementary. That is, an opaque element in one disc corresponds exactly in size, shape, transverse position and orientation to a transparent element in the other disc. One disc can 4 thus be produced from the other by simple photographic printing. In this case the transmissivity of the sight as a function of the angle of transmission measured from the axis of the cylinder is just an analog representation 'of the autocorrelation function of the pattern on one of the discs.

When only two pattern planes are used, one being the inverse or negative of the other, it is possible to position them so that they are not normal to the lines of sight and/ or so that they are not mutually parallel, only providing that the images tend to obliterate.

FIGURES 9 and 10 represent a pattern made of small circular areas randomly positioned, one figure being the negative of the other. This pattern produces a reticle consisting of a single black spot or dot surrounded by a light field. The pattern of random position may be termed the gross pattern, while the shape of each element, here a circular area, may be termed the fine pattern.

When such a pair is used in the sight of FIGURES 1 and 2, the pattern diameters may be, for example, onehalf inch, the distance between the two pattern planes one inch and the distance between the rear plane and the eye one inch. These dimensions are not critical. The closer the eye is placed to the sighting device the better, one inch being deemed near enough to the sighting device for proper operation but far enough for suitable design and comfortable operation. One-half inch diameter of the patterns is deemed enough to permit considerable latitude in transverse placement and movement of the head and eye of the observer. It will permit a lateral aiming error of A inch at the target at all ranges, which will in many cases be negligible. The longitudlinal spacing of the two patterns influences the reticle dot size, as described. However, the forward pattern must not be positioned so far from the eye as to enable the eye to focus on it. Although this distance is different for different eyes, a maximum of two-inch distance of the forward pattern from the eye is deemed reasonable.

The lateral aiming error due to sideways movement of the eye within the width of the sight can be eliminated for any single range by making the front pattern slightly smaller in scale than the rear transparency, so that any line from the eye to the target center, at any eye position, encounters an opaque element in one transparency and a transparent element in the other.

The optics of this embodiment of the sighting device are indicated in FIGURE 11, in which the arrow 24 indicates a distant target object. The lens of an observers eye is indicated at 26, with the retina at 27. The edge views of the two pattern planes of a sighting device such as shown in FIGURES 9 and 10 are indicated by the rectangles 28 and 29. These patterns are to the same scale. The rays from the ends of the target object 24, crossing without refraction at the center of the lens 26, define an image 31 of the target object on the retina. The two patterns, 28 and 29, are congruent in the direction of the axis 32 and in the directions of all rays parallel to axis 32. Therefore, any such ray is interrupted by an opaque element of either one or the other pattern. This interruption constitutes the reticle dot.

FIGURE 12 is a pattern similar to but not identical with FIGURE 9. The positions of the dots are identical but the dots in FIGURE 12 are smaller than those in FIGURE 9. Therefore, when FIGURES 12 and 10 are used together as the patterns of a two-plane sight, their projection on a transverse plane will not fill the cross-section of the cylinder. As a result, both the dark reticle and the surrounding light field will be lighter, as was mentioned earlier.

It is possible to emply two patterns in the two-plane sight which are not the photographic positive and negative of the same pattern and which employ elements different in shape in the two patterns. For example, the pattern of FIGURE can be employed with a pattern shown in FIGURE 13. This patterns consists of many crosses composed of vertical and horizontal lines. Their placements are such that the position of each cross exactly corresponds to the position of one of the transparent discs of FIGURE 10. When FIGURE 10 is used as one of the patterns of a two-plane sight, preferably the rear pattern, and the pattern of FIGURE 13 is used as the other, maintaining its orientation as described and shown, a reticle will be formed consisting of a single dark cross on a light field, as shown in FIG- URE 8. The transmissivity of the sight is an analog representation of the cross-correlation function of the two patterns.

Many other forms of reticles can be generated by similar means such as, for example, a reticle consisting of a dark dot surrounded by several dark, concentric circles.

It is possible to generate a light reticle superimposed on a dark field, if selected lines drawn parallel to the axis of the sight intersect at least two opaque elements. In addition, it is neecssary that the opaque elements, when projected to a single transverse plane, do not cover it completely. This form of sight is preferable in some cases but generally the dark reticle form is preferable because the contrast between the reticle and the surrounding field can be high, while in the light reticle case the contrast is on the order of two to one.

When the simplified, two-plane sight is considered, it is evident that, in order to generate a light reticle on a darker field, the two patterns must not be positive and negative of the same pattern, but both must be either positive or negative. For example, two copies of the pattern of FIGURE 12 could be employed to generate a light reticle on a darker field.

It is possible to employ patterns tinted with transparent colored dyes to form colored reticle images, both in the two-plane case and when more than two planes are used. For example, when employing the positive and negative reproductions of a pattern in a two-plane sighting device to form a dark reticle image on a lighter field, various parts of the pattern reproductions can have selected degrees of light transmissivity and can be tinted, to form various color combinations in the observed reticle image and surrounding field.

What is claimed is:

1. A sighting device comprising, a number of substantially opaque elements positioned in at least two spacedapart limited planes in space, the areas of said planes not occupied by said opaque elements being substantially transparent, said spaced-apart limited planes intersecting the same straight line, the transverse arrangement of elements in each said plane composing a gross random pattern occupying at least a substantial central area of each plane, a holder for said elements, said elements being so positioned and oriented that the gross patterns of all said elements in all said planes when projected to a single transverse plane do not substantially overlap.

2. A sighting device comprising, a first sheetlike member bearing a random pattern of cruciform elemental areas thereon, a second sheetlike member bearing a plurality of dotlike elemental areas thereon arranged in a gross pattern identical to that of said first member, a holder, said members being positioned in said holder in spaced- 6 apart relation and so oriented that the patterns of said members are congruent with respect to parallel lines of sight passing corresponding elemental areas of each.

3. A sighting device comprising, a plurality of members each bearing a pattern of substantially opaque and substantially transparent elemental areas thereon, the elemental areas of each being arranged in a gross random pattern occupying at least a substantial central area of each member, and a holder therefor, said members being positioned in said holder in spaced-apart relations and each being so oriented that the gross patterns of all of said members are congruent with respect to parallel lines of sight passing through corresponding elemental areas.

4. A sighting device comprising, a pair of sheetlike members each bearing a random pattern of substantially opaque and substantially transparent elemental areas occupying at least a substantial central area of each sheetlike member, the elemental areas of one member being similar in size, shape and location to those of the other, a holder therefor, said members being positioned in said holder in spaced-apart parallel relation and each being so oriented with respect to the other as to have identical attitudes.

5. A sighting device comprising, a pair of sheetlike members each bearing a random pattern of substantially opaque and substantially transparent elemental areas occupying at least a substantial central area of each sheetlike member, the elemental areas of one member being the same in size, shape and location as those of the other, a holder therefor, said members being positioned in said holder in spaced-apart parallel relation and each being so oriented with respect to the other that corresponding elemental areas of each are intersected by lines parallel to the longitudinal axis of said holder.

6. A sighting device comprising, a pair of sheetlike members each bearing an identical random pattern of substantially opaque and substantially transparent elemental areas occupying at least a substantial central area of each sheetlike member, a holder therefor, said members being positioned in said holder in spaced-apart parallel relation with each being so oriented with respect to the other that like corresponding elemental areas are intersected by lines parallel to the longitudinal axis of said holder. 1

7. A sighting device comprising, a plurality of members each bearing a pattern of substantially opaque and substantially transparent elemental areas, the pattern of elemental areas occupying at least a substantial central area of each member, the area of each elemental area being small compared to the area of the pupil of the human eye, the elemental areas of each member being arranged in a gross pattern, and a holder therefor, said members being positioned in spaced-apart relation and each being so oriented that the gross patterns of all of said members are congruent with respect to parallel lines of sight passing through corresponding elemental areas.

References Cited by the Examiner UNITED STATES PATENTS 2,418,436 4/47 Talbot 88-1 2,553,540 5/51 Beckerman 33-47 ISAAC LISANN, Primary Examiner.

Claims (1)

1. A SIGHTING DEVICE COMPRISING, A NUMBER OF SUBSTANTIALLY OPAQUE ELEMENTS POSITIONED IN AT LEAST TWO SPACEDAPART LIMITED PLANES IN SPACE, THE AREAS OF SAID PLANES NOT OCCUPIED BY SAID OPAQUE ELEMENTS BEING SUBSTANTIALLY TRANSPARENT, SAID SPACED-APART LIMITED PLANES INTERSECTING THE SAME STRAIGHT LINE, THE TRANSVERSE ARRANGEMENT OF ELEMENTS IN EACH SAID PLANE COMPOSING A GROSS RANDOM PATTERN OCCUPYING AT LEAST A SUBSTANTIAL CENTRAL AREA OF EACH PLANE, A HOLDER FOR SAID ELEMENTS, SAID ELEMENTS BEING SO POSITIONED AND ORIENTED THAT THE GROSS PATTERNS OF ALL SAID ELEMENTS IN ALL SAID PLANES WHEN PROJECTED TO A SINGLE TRANSVERSE PLANE DO NOT SUBSTANTIALLY OVERLAP.

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