Patent GB-144269-A (GB)
Title: Improvements in devices for tracing from a photostereogram on a plane surface linearelements of the surface of a spatial form
IPC: G03F7/00
Filed: 1920-05-31
Abstract: 144,269. Zeiss, C., [Firm of]. July 8, 1918, [Convention date]. Stereoscopic apparatus.-Relates to apparatus by which linear elements of a spatial surface can be traced on a plane surface from a photostereogram the apparatus comprising a stereo-comparator consisting of a binocular double microscope M having two marks, and a system of four slides A, B, C, D carrying the photograms and connected by lever systems to the copying-slides A1, B1, C1. The invention consists in the adaptation of such apparatus to copying from a stereogram produced by an optical system in which the two optical axes are inclined at different angles (denoted by #1 and #2) to the horizontal, the base-line, i.e. the line connecting the centres to the objectives, is inclined to the horizontal at an angle E, the horizontal projections of the optical axes are inclined to each other at an angle y and the horizontal projection of the left-hand optical axis is inclined at an angle a to the horizontal line at right-angles to the base line. The adaptation is effected by so connecting the slide A1 with the points of application on the slide B1 of the lever systems connecting the slides B, B1 and C, B1 that these points receive, when the slide A1 is displaced, the required settings according to equations, given in the Specification, connecting the solid co-ordinates X, Y, Z of any point with its co-ordinates x, y, and x2, y2 on the photograms. In the form shown in Fig. 1, the microscope M is mounted on the slide A. displaceable in the depth-direction, the left-hand photogram on the slide B, displaceable in the breadth-direction, and the right-hand photogram on the cross-slides C, D, the slide C being displaceable in the breadthdirection and the slide D being manually adjustable over the slide C in the depth direction. The slide A1 is mounted on the slide C1 and is moved in the breadth-direction relatively thereto by a screw a, operated by gearing a2 - - a6 from a foot wheel a,. It is connected to the slide A by a lever system comprising a lever e1, e2, rod e4, bell-crank lever e5, e6, slide e8, and rod e9. The arms e1, e2 are set at an angle 180‹ + #1 to each other, this angle being indicated on the scale e15; the line joining the axes Q0, Q<1>0 lies in the breadthdirection, and the arms e2, e5 are of equal length. The arm e6 has a slot e7 engaging a pin Q on a slide e10 which is set so that the distance Q<1>0Q represents f, the focal length of the objectives. The slide B, is also mounted on the slide C, and is moved in the breadth-direction relatively thereto by a screw b1 operated by a hand-wheel b, through gearing b2 - - b7. This slide carries the tracing-point z1 moving over the surface z2. The slide C1 is moved in the depth-direction by screws c1, c2, connected by gearing c5, c7 and operated by a hand-wheel c3 and chain c4. The slides B, B1 are connected by a straight lever d1, d2 pivoted at O9. The arm d2 has a slot d4 engaged by a pin O on a slide d5 connected by an arm d6 to the slide B, and the arm d1 has a slot d3 engaged by a pin O1 on a block m1 mounted in a slide secured to the slide B. The depth component of the distance O0O is set to the value f/Cos#1 and the distance O1O0 is, when the indices m2m3 coincide, equal to the depth component of the distance Q1Q0, and represents the co-ordinate Z. The slides C, B, are connected by a lever h1, h2 the arms of which are set at an angle 180‹ + gamma to each other; the arm h2 has a slot h4 engaged by a pin P carried by a slide h5 which is set so that the depth component of the distant P0P represents f/Cos#2. The arm h1 has a slot h3 and is connected to the slide B, by a series of slides comprising a slide i, displaceable over the slide B1, a slide i5 displaceable in the slide i, a revolving slide i11 on the slide i5, and a slide i9 movable in guides i10 on the slide i11. The slide i9 carries a pin P1 engaging the slot h3. When the slides are in their zero positions the depth component of the distance P1P0 is equal to Z. The movements of the slide A, are transmitted to a slide A1<SP>1>, also mounted on the slide C1, through gearing a10, a9, and screw a8. The connexion between the slides A1<SP>1> and B1 comprises a pair of slides n1, o1 displaceable over the slide C, in the depth direction and having slotted portions n3, o3 respectively engaging the pins O1, P1. The slides n1, o1 also carry extensions n4, o4 passing through blocks n5, o5 mounted in slots n7, o7 in arms n8, o8 pivoted at n9, o9 on the slide A1<SP>1>. The arms n4, o4 can be secured in their respective blocks by clamps n6, o6. The arm n8 is set at an inclination #1 to the horizontal and the arm o8 is set to an inclination #, given by tan # = tan B2 Cos gamma ; these angles are indicated on scales n11, o11. The manner in which the photograms and the microscope are disposed on the slides A, B, C, D may be varied; for instance the microscope may be rigidly fixed and the stereogram carried by the slide A, the photograms being respectively carried by the slide B and by the cross-slide system C, D which are movable within the slide A; the linkage mechanism is then correspondingly altered. A modified form of the linkage mechanism is described which is arranged according to a set of equations which are equivalent to those referred to above but of different form. A modification is also described in which the point of application on the slide B of the lever system connecting the slides B and B1, and that on the slide C of the system connecting the slides C and B1, are respectively coupled with the slides A and D in such a manner that a displacement of either of the latter slides in the height-direction of the photograms causes a setting of the point of application coupled with it relatively to the respective slide B or C in the same direction. Specification 10645/14 is referred to.