GB345907A - - Google Patents

Abstract

345,907. Stereoscopic apparatus. ZEISS, C., Carl-Zeiss-Strasse, Jena, Germany. July 12, 1930, No. 21148. Convention date, July 26, 1929. [Class 97 (i).] In a binocular observing instrument for stereogrammetric measuring - apparatus, having exchangeable reflectors to enable the observer to obtain at will either a stereoscopic image or a pseudo-stereoscopic image (i.e. one in which the right eye sees the image appropriate to the left eye and vice versa), the reflectors comprise two differently constructed prism systems mounted on a carrier which can be moved so as to bring either system into the path of the rays. In the form shown the two systems are mounted on a rotatable carrier, one system comprising two single-reflecting prisms e<1>, e<2> which, in conjunction with fixed prisms cl, c<2> and objectives b<1>, b2 render the half images E<1>, E<2> visible in the eyepieces a<1>, a2 respectively, a stereoscopic image being thus obtained. The second system comprises prisms f<1>, f<2>, f<3>, the prism f<3> having surfaces f<3'>, f<3>" which are parallel to the reflecting surfaces of the prisms e<1>, e2 respectively, and are separated from the prisms f<1>, f2 by thin air layers. This system is inserted in the ray paths by turning the carrier through 180‹ from the position shown, and renders the images E<1>, E<2> visible in the eyepieces a2, a<1> respectively. Lenses g<1>, g<2> compensate for the altered lengths of the ray paths. In another form the two systems are mounted at different levels on a vertically-displaceable carrier.