GB475808A - Light dividing device - Google Patents

Abstract

475,808. Optical systems; colour photography. TECHNICOLOR MOTION PICTURE CORPORATION. May 25, 1936, No. 14723. Convention date, Jan. 16. [Class 97 (i)] A light-dividing system for colour photography &c., of the type employing contacting prism elements with partly reflecting as well as totally reflecting surfaces, consists of a prism element receiving the incident light and forming with at least two additional prism elements at least two partly reflecting surfaces inclined to each other, at least one element having a totally reflecting surface inclined to the partly reflecting surfaces for deviating a component beam coming from a partly reflecting surface. The form shown in Fig. 1 consists of three similar right-angled prisms 1, 2, 3 placed in contact with each other, the contact surfaces 16, 17 being rendered partly reflecting. A beam R incident normallv on the surface 5 of the prism 1 is partly reflected at the surface 16, the reflected beam A being totally reflected at the surface 5 to emerge normally from the surface 11. The beam B transmitted by the surface 16 is again divided at the surface 17, the beam C reflected by the latter surface emerging normally from the surface 12 while the transmitted beam D emerges normally from the surface 13. In Fig. 2, the prism 3 is omitted and the prism 2 is divided into two prisms 32, 33 having a partly reflecting contact surface 37. In this form, total reflection occurs at the surfaces 5, 36. As shown in Fig. 1, the images a, c may be recorded on a double-width film W moving in a direction parallel to the apex line of the prism combination, the image d being recorded on an ordinary film F also moving parallel to this line. Alternatively, as in Fig. 2, the images a, c may be formed on successive spaces of an ordinary film 43 moving at right-angles to the apex line, the film 44 also moving at right-angles to this line. Fig. 4 shows a system producing four images and consisting of three similar isosceles prisms 61, 62, 63 placed in contact to form a combination of equilateral triangular section, the contact surfaces 64, 65, 66 being partly reflecting. The paths of the rays forming four images k, m, n, p are clear from the Figure. With this form the four images can be viewed simultaneously in superposition by a lens Q. U.S.A. Specification 1,738,095 is referred to.