Patent GB-1473537-A (GB)
Title: Stereo television microscope
IPC: G02B21/22
Filed: 1974-06-17
Abstract: 1473537 Stereo television microscope J F BUTTERFIELD 17 June 1974 26791/74 Heading H4F A stereo television microscope for providing a three-dimensional enlarged view of an object 7 comprises optical means 9-13 for optically picking up images of the article from two angles, these images being maintained separate and being optically channelled to a pick-up tube 6, the resulting video signals being displayed, e.g. on CRT5, as respective enlarged visual images which are channelled to the respective eyes of a viewer. The microscope is also provided with an arrangement for adjusting the stereo base for optimum perception of depth at adjustable working distances (distance between optics 9 and object 7). As shown, Figs. 1 and 5, light from object 7 passes through a plate 9 including wedge prisms 41 and 42 forming part of a beam splitter which picks up a stereo pair of images from slightly different angles, shutters 10 including a pair of blades 43 and 44 operated by control knob 38 which comprises the stereo base control, crossed polarizers 11a, 11b, and a lens system 12 including an iris 13, the two images then being reflected via mirror 14, crossed polarizers 15a, 15b, Fig. 7, and mask 16 on to a vidicon pick-up tube 6. The video signal derived from the two adjacent images is then displayed as two adjacent images on CRT5 and viewed via an apertured mask 4, a hood 1a, an optical plate 3 and a visor 2. Plate 3 includes two wedge prisms 39 and 40, Fig. 4, mounted adjacent apertures 27 and 28 in a mask plate, these prisms acting to superimpose the images. Pickup tube 6 may be moved horizontally in cradle 20 by turning focus control knob 21, and the carriage 17 and cradle 20 may be moved vertically by turning knob 22 to cause magnification variations i.e. zooming, the horizontal position thereof being simultaneously adjusted via mechanical linkages. The video signal may be connected to other stereo microscope displays or recorded on video tape, alternatively other external video signals may be displayed on the CRT. A mask divider (29, Fig. 2, not shown) ensures that each eye only sees one of the stereo image pair. Stereo base control knob 38 may be tied to control knob 22 so as to vary the stereo base at the same time as the magnification is adjusted. Prisms 41 and 42 may be replaced by Fresnel prisms, and lens 12 may be on a typical microscope turret. To increase the stereo base without reducing the working distance two additional prisms (45 and 46, Fig. 8, not shown) may be located between shutters 10 and lens 12; movable apertures may be located between polarizers 11 and lens 12 instead of shutters 10 (Figs. 9A, 9B, not shown); prisms 41 and 42 may be replaced by an adjustable reflective arrangement shown in Fig. 10; or lens 12 may be replaced by a matched pair of lens (52, Fig. 11, not shown) with or without a central baffle (53). Another embodiment using a matched pair of lens with an arrangement similar to Fig. 10 is described with reference to Figs. 12 and 13 (not shown). The microscope may include two pick-up tubes, one for each of the stereo pair, with two CRT displays. The images may be transmitted sequentially using an appropriate shutter or oscillating reflector, a rotating filter at the CRT and filters in front of the eyes being used. Reference is also made to the use of lenticular lenses. The object may be illuminated with infra-red or ultra-violet. Reference is also made to using mechanical scanning pick-up means, colour television pick-up and display, false colour display, polarity reversed display, photographing the stereo-pair displayed on the CRT, and removal of the stereo-optics to enable non- stereo viewing.