GB662803A - Device for four colour stereoscopic cinematography - Google Patents

Abstract

662,803. Optical systems. CRISTIANI, L. Oct. 7, 1949, No. 25847/49. Class 97 (i). Four images, forming two stereoscopic lefteye and right-eye colour component pairs, are produced by a system including means for producing first a pair of images, with a stereoscopic separation, which means divides the entry pupil of the system into two parts used by the two corresponding light beams which are then collimated and fall on pairs of faces of a pyramidal prism with which are associated pairs of complementary colour filters, the four light beams from the prism being used to form four adjacent images on a film. In the form shown, pairs of reflectors are disposed in front of an. objective 1 and comprise outer mirrors 3 and the faces of a prism 31. Separate mirrors or two rhomboidal prisms may be used instead. The objective produces stereoscopic images in superposition in the aperture 2<SP>1</SP> of a diaphragm 2. A field lens 4 and an objective 5 together have a principal focal plane at the diaphragm and, accordingly, parallel light falls on a pyramidal prism 6, with each face of which is associated a colour filter 7. Four images are formed in a normal film frame space at 9 by an objective 8. The four filters may be so chosen that their transmissions lie in four consecutive spectral zones so overlapping that the colours of the first and third, and second and fourth respectively form complementary pairs for use in the light beams from the two stereoscopic images. For projection the same optical system is used with polarizing filters for polarizing differently the light beams from the left- and right-eye colour component images. Polarizing spectacles are used for viewing wherein the polarizing material may occupy only a small area in front of the eye pupil.