US2045093A - Stereoscopic photography - Google Patents

Description

June 23, 1936. H. s. NEWCOMER STEREOSCOPIC PHOTOGRAPHY 4 Sheets-Sheet 1 Filed Sept. 30, 1933 INVENTOR 7 HAPPY 5. NEH (OM51? ATTORNEY J1me 1936. H. s. NEWCOMER STEREOSCOPIC PHOTOGRAPHY Filed Sept. 30, 1933 4 Sheets-Sheet 2 INVENTOR HARRY 5'. NEWCOMEI? figia J2 ATTO R N EY June 23, 1936. s. NEWCOMER 2,045,093

STEREOSCOPIC PHOTOGRAPHY Filed Sept. 30, 1935 4 Sheets-Sheet 3 INVENTOR I HARRY 5. NEWCOMER ATTORNEY Patented June 23, 1936 UNITED STATES PATENT OFFICE STEREOSCOPIO PHOTOGRAPHY Application September 30, 1933, Serial No. 691,604

5 Claims.

The invention relates to method and means for photographically producing an interlined stereogram which may be employed either as a still picture or as a motion picture.

It has heretofore been proposed to photographically produce an interlined stereogram by the use of an arcuate array of plane station mirrors arranged on a base line which is concave, as seen from the object to be photographed. In conjunction therewith is employed an arrangement of assembly mirrors which collects the refiected images in the station mirrors and diverts the same along optical paths having different horizontal inclinations to a lineater and a light sensitive surface.

In one aspect of the matter, this invention relates to improvements over the above proposal, and has for its object, to overcome certain defects therein, namely, to obtain a more uniform illumination of an extensive image field at the lineater than is possible with the above arrange ment wherein the objective lens receives light rays at substantially different angles for each discrete view of the object. This is accomplished by arranging the light rays for each discrete view of the object, to be received by the objective lens, along paths substantially parallel to the axis of the objective.

The advantage of photographing the object from a plurality of discrete viewpoints is to produce a stereogram wherein the picture line elements are what has heretofore been called stripes, in that the picture line elements contain no smeared record of the object as is the case when the object is photographed from an infinite number of viewpoints.

The ability to impress on the objective, light rays from the several discrete viewpoints along optical paths which are parallel to the axis of the objective, is enhanced by the use of an arrangement of assembly mirrors which is in close proximity to the objective lens and which assembly is preferably mounted on and forms a part of the objective. Preferably, the station mirrors are also mounted on, or are integrally united with the objective lens.

One of the advantages of the arrangement by which the light rays from the different stations come in parallel to the axis of the objective, is that the images of corresponding points of the object, at least the images of the central object point, lie within the same group of image stripes, whereas when the light pencils come in from different stations at substantially different angles, the image points of corresponding object points, or at least the images of the central ob ject point, lie at substantially different points in the image surface.

One disadvantage .of this displacement. of. images of corresponding object points taken from different stations failing to substantially coincide, which disadvantage I overcome, is that each such image as a whole will contain marginal portions not found on the other, or at least to a substantial extent. 10

In the particular embodiment herein disclosed,

I have arranged an arcuate array of station mirrors on a base line which is convex as seen from the object photographed. This has the disadvantage that the length of the optical path from 15 the object to the objective is diiferent for each discrete viewing station. I overcome this defect in several ways; for example, by employing station mirrors which are curved or spherical, or by employing a correcting lens or lenses in the path of the rays from one or more of the station mirrors.

The parallactic displacement of the images constituting the picture line elements, and the angular separation of the pencils from the diifer- 25 ent stations which this implies, is obtained by impressing the pencils of the different stations upon different zones of the objective, whereby these pencils emerge from the objective and converge upon the image point at different angles 30 to the axis of the objective in the horizontal plane.

For further details of the invention, reference may be made to the drawings wherein Figure 1 is a schematic plan view of a. photographing ar- 35 rangement according to the invention, certain of the station mirrors being not shown. Figure 2 is a schematic sectional view of an objective with means for correcting for non-uniformity in the length of the optical path for the several discrete viewpoints. Figure 3 is a modification of Figure 2. Figure 4 is a schematic perspective view of an objective lens which has integrally mounted therewith the station mirrors and also the assembly mirrors. Figures 5, 5A, 6, 6A, are plan views of different types of apertures employed to investigate the definition afforded by different zones of certain objectives, and the resulting definition of which is shown schematically in 50 Figures 53, 50, 6B, 60, respectively. Figure 7 is a sectional plan view on the optical axis of the objective in Figure 4. Figure 8 is a sectional elevation on line 8-8 of Figure 7. Figure 9 is a sectional elevation on line 99 of Figure 7. Fig. 55

10 gives the data for the objectives of Figs. 1, 2, and 3.

Referring to the drawings, there is provided an arcuate array of plane station mirrors, (1, 2, 3, the centers of which are arranged on a base line which is convex as seen from an object (not illustrated) to be photographed, and from which the lines of light emerge and reach each such mirror as illustrated. It will be understood that three other station mirrors not illustrated, are likewise symmetrically disposed on the opposite side of the optical axis 4 of the objective lens 3. Each station mirror I, 2, 3, etc., receives an image of the object from a substantially discrete viewpoint and reflects the same to its associated assembly or segment mirrors 6, I, 8, respectively, the other three station mirrors which are not illustrated, likewise reflecting discrete angular views of the objects to their associated assembly mirrors 9, I0, II, respectively.

The station mirrors I, 2, 3, etc., and their associate assembly mirrors 6, l, 8, etc., are angularly disposed so that the rays from the central object point, when reflected from the assembly mirrors 6, I, 8, etc., pass through the objective along lines substantially parallel to the optical axis 4 of the objective 5. The assembly mirrors 6, I, 8, etc., divide the anterior pupil of objective 5 into seven approximately equal areas, of which the central one is not covered by a mirror. The objective 5 focuses the several discrete angular images of the object, including the image which the objective receives directly without reflection between mirrors B and H, through an opaque line screen or other lineater I2, onto the light sensitive surface I3. The light sensitive surface I3 thus receives a multiplicity of parallactically displaced images corresponding to the difierent angular views of the object in horizontal extension as the several angular or station views of the object are focused by the objective 5 upon the lineater by pencils having different horizontal inclinations to the axis of the objective. For example, it will be seen that the central pencil from reflector 6 passes through an, outer zone of the objective 5, and is inclined to the axis more in being focused on lineater I2 than is the central pencil from the other assembly mirrors.

I have discovered that it is possible to place the station and assembly mirrors as illustrated in Figure 1, so that under conditions representing suitable relationships between the focal length, or what in motion picture photography is the same thing, the angular opening of the lens, and the number of station mirrors, there is no diaphragming or interference of the station mirrors, the one by the other.

also correspond in each instance to the margins of the image frame, are indicated by the numbers I6, I I, and I8. 0n the image side the principal rays from the central object point via the various stations are indicated in an entirely.

schematic fashion by the numbers I9, 20 and 2|.

The station mirrors I, 2, 3, etc;, of Figure 1 are shown with their centers equally spaced with respect to each other on a horizontal base line perpendicular to the optical axis and the ray from the central object point to the center of the outside station makes an angle of 1 4 with the axis at the central object point. Such an angle is small enough to make a reasonably compact drawing. In practice a somewhat larger angle will frequently be preferable. 5 is for instance The margins of the beams on the object side for each station, margins which a preferred angle. The preferred angle may increase with the number of stations.

As drawn in Figure 1, the station mirrors I, 2, 3, etc., do not diaphragm one another; that is, they do not interfere with one another. It will be found that when for any given arrangement such is the case, then the station angles may be in creased or decreased, maintaining the while the equi-angular spacing of the stations, without substantially altering this non-interference of the station mirrors with each other.

Similarly within reasonable limits the size of the lens opening and hence of the aperture mirrors is without important effect on the station mirror interference.

The number of station mirrors shown in Fig. 1 is 6. It is not however intende to limit the number to this figure. The number ofnon-interfering station mirrors which may be placed or used is, when equi-angular spacing is' required dependent upon the angular opening of the photographic lens. Since we may for practical purposes, at least for purposes of illustration, assume standard motion picture film and hence'flxed image dimensions, the number of non-interferring stations is dependent upon the focal length of the lens.

For standard film one may place 6 non-intering mirrors (7 stations) in the caseof a 3" lens,

and 8 non-interfering mirrors (9 stations) in the case of a 4" lens. Similarly greater focal lengths permit the placingof still more stations. However, it is a, general property of photographic objectives that the quality of the image decreases with increasing focal length and hence there is a limit beyond which increase in focal length is not practical. For usual so-called close-ups, this limitation is less operative, detail in the image being less necessary. Another limiting factor is the number of segment mirrors which can be placed in front of the objective and still provide sufliciently separate light paths through the objective, even when considerable blending is desired.

The aperture areas of lens 5 corresponding to the individual assembly mirrors 6 to II have been made substantially equal, thus providing substantially equal illumination of the corresponding image stripes on the sensitive surface; When the lens 5 of Figure 1 gives unequal transmission and light loss through the different segments thereof, this might be compensated for by an appropriate alteration in the segment area.

In Figure 1 the lens 5 is indicated as a 3" lens working at a numerical aperture of 72.8. A larger or smaller aperture could be used; but this is about the average largest aperture at which present day photographic objectives still give quite good definition. I

From simple inspection it is apparent that the optical path from the object to the objective 5, is longer by way of mirrors l and 6 than it is by way of any other pair of mirrors on the same side of the optical axis 4. The length of the optical path decreases for mirrors nearer the optical axis 4. I may substantially correct this difference in path,'either by a positive lenselement I4 placed in front of the central portion of the objective 5 as illustrated in Figure 1, or by separate positive or negative lens elements such as I5 for each zone of objective 5 is in Figure 3, or by curving the assembly mirrors such as 9' of objective 22 as in Figure 2, or by curving the station mirrors such as I in Figure 2. The curvatures are shown exaggerated for purposes of clarity of interpretation. The curvature or strengths necessary to neutralize the differences in light path is easily deduced from the elementary properties of image forming systems. It is naturally different for each pair of stations. The separate correct lens elements are preferably eccentrically cut so as to be concentrically surfaced with respect to the axis of the objective 22.

The objective lens 5 as employed herein, must meet requirements considerably more rigid than the requirements for commercial motion picture photography, in that each of the several segments of the objective, that is, seven segments in the case of Figure 1, must focus an image with good definition on the light sensitive surface i3. I have examined a large number of available objectives,-

and the conclusions drawn will now be explained. Using a typical motion picture lens of high quality, I have photographed an object comprising a screen with vertical rulings. When thus photographed through the diaphragm 8| having central aperture 82, the result is as shown in Figure 5B wherein the definition of the marginal portions 88 and 81 is, as is always the case, even with unsegmented aperture, not as good as the definition at the central portion 85. The amount of marginal image deterioration schematically indicated is such as is ordinarily found acceptable. Furthermore, when the ruled screen is photographed through the diaphragm 83 of Figure 5A, and having the marginal segment opening 84, the result is shown in Figure 50 wherein the definition at the margin 90 is very poor, the definition at margin 89 substantially as before, and the definition in the region 88 on the opposite side of the center from aperture 84 is normally good, the deterioration of the image margin 98 extending to beyond the center of the image field.

I do not intend to imply by this illustrative embodiment as shown in Figure 5 that a deterioration of motion picture images produced by lateral segmentation of the lens is always of the type described. There may be less marginal deterioration and more central deterioration, or there may be deterioration that will involve other portions of the image.

In addition, certain motion picture objectives which are otherwise very satisfactory for general motion picture purposes, give a definition too poor for the delineation of details required in panoramagrams.

In Figure 6, I showby way of illustration, and in schematic fashion, the manner in which certain satisfactory objectives can be segmented without appreciable deterioration of the image. In fact there may be actual improvement of the image as a result of segmentation.

At 9| I show a diaphragm with a central rectangular aperture 82, as in 8| and 82, Figure 5; and 93 a diaphragm with a lateral segmented aperture 94, as in 83 and 84, Figure 5A. As in Figure 5, below these segment apertures there are shown schematically the images formed by a lens suitable for the purpose of the invention when im aging an object, in this case a lined screen.

At 95 is shown the central portion of-the image resulting from the use of a centrally located segment, and at 98 and 91, the lateral portions of the same image. These lateral portions, 98 and 91,

are as is usual with motion picture lenses as nor-' mally used, somewhat less well defined than the I central portion, 95.

At 98 I show the central portion of an image of the same object using the laterally disposed segment aperture 84, and at 89 and I 00 the lateral portions of the same image. These lateral portions 98 and I00, may be substantially the same as 96 and 91, or they may show very slight less definition when satisfactory objectives are used.

In particular, there is an improvement of the region shown at I00 over the region 91 when an objective of the type shown in Figure 2 is used.

The drawing is a schematic representation of the type of images obtained with lens of the type 10 shown in Figures 1 and 3.

The lens shown in Figure 3 is the same as the lens shown in Figure 1. The characters refer to the characters used below to designate the numerical dimensions of the lens. 15

The lens shown in Figure 2 is also as in the case of Figure 1 a lens suitable for the purposes of the invention. This in common with the lens shown in Figure 1, consists of a negative element placed between and substantially spaced from two posi- 20 tive members anterior and posterior. The characters refer to the characters used below to designate the numeral dimensions of the lens.

Data for the objective of Figures 1 and 3 25 T1=+49.5 d1: 7.08 heavy crown v==56.3 nc=1.61045 ns=1.62136 r2: infinity 61: 22.1 39 7'3=-57.36 (12: 2.44 heavy flint v=28.2 nc=1.71878 r4=+63.21 1 e2: 16.76 T5=+467.8

d3= 6.3 heavy crown 1 :56.9 nc=1.61949 .nr=1.63044 T6=-57.6 63: 1.2

(14: 4.:s2 heavy crown 11:56.9 nc=1.61949 nr==1.63044 rs=-185.4

F=100 opening F/2.3

Data for the objective of Figure 2 T1=+32.48 di= 4.76' heavy crown v= 59.4 nc=1.6032

7lr=1.6134 r2= infinity 81: 5.63

ra=72.8 d2: 3.57 light flint v=40.9 n =1.5771 65 1lr=1.5913 r4=+29.56 62: 6.8 r5: infinity d3: 1.53 ex. light flint v=51.8 110:1.5255

nr=1.5357 r6= 29.56 d4: 8.25 heavy crown v=56.6 1Lc=1.6191

F= opening F/3.5

in Figure 4 is provided with two parallel shelves 7 Cal 23 and 24 between the station mirrors l, 2, 3, etc., and the assembly mirrors 6 to l I the permanently fixed relatively to each other and to the objective 5, the shelves 23 and 24 being suitably fastened, for example, by soldering or welding to the lens tube 25 of the objective 5. Also the shelves 23 and 24 may be further supported and spaced apart by means of posts 26, 21, 28, 29, 30, 3|, which are fastened to both shelves 23 and 24 in positions out of the lines of sight of the several mirrors.

For motion picture work, the sensitive surface l3 would comprise motion picture film operated at a motion picture speed to produce a stereoscopic record of the successive kinematic phases of a moving object. In this case the lineater I2, which may be integral with the film,

should preferably have more than 300 and less than 600 lines per inch.. Also the ratio of the transparent to the opaque portions of the lineater 12 should be substantially as one to the number of viewing stations, which in the case of Figure 1 is I, thus providing in the emulsion I3, picture line elements, in fact stripes, which are of the order of, or at least equal in width to, the average width of five silver grains in the emulsion as further described and claimed in the copending application of Arthur W. Carpenter, Serial No. 690,830, filed September 25, 1933.

The stereogram of this invention may be projected as illustrated in Figure 8 of the French patent to Bessiere, No. 590,853.

It will be apparent that the objective 5 with its associated station mirrors I, 2, 3, etc., and segment mirrors 6, 1, 8, etc., may be used for projection as well as for photography.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent, is:

l. Arrangement for photographically producing an interlined stereogram comprising means to support a light sensitive surface, a lineater, an objective lens having more than two zones adapted to transmit a corresponding number of discrete images of an object respectively with substantially equal light intensity and definition, and means comprising an arcuate array of a plurality of pairs of separate mirrors for admitting to the entrance pupil of said objective an 5 image of a different angular view of an object for each of said zones, said lineater and said light sensitive surface being on the opposite side of said objective from said admitting means.

2. Stereoscopic apparatus comprising an objective lens, a multiple station light transmitting device fixed thereto and portable therewith, said device comprising a pluralityof pairs of station mirrors and corresponding segment mirrors, and means for equalizing the intensities of the light 15 beams reflected by diiferent pairs of said mirrors.

3. Stereoscopic apparatus comprising an objective having a plurality of pairs of segments,

a segment mirror for each of said segments, a station mirror for each of said segment mirrors, said station mirrors being arranged on an arcuate horizontal-base line, and means for securing said segment mirrors and said station mirrors to said objective. I

4. Stereoscopic apparatus comprising an objective' having more than three segments, means comprising a segment mirror for each of said seg- -one mirror of said assembly on the same side of a plane passing through the center of said objective and said array of plane mirrors.

HARRY S. NEWCOMER.

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