GB1453020A - Scanning system including a holographic spinner - Google Patents

Abstract

1453020 Optical scanning PERKIN-ELMER CORP 23 May 1974 [29 May 1973] 23132/74 Heading G2J A line scanner e.g. a high resolution high bandwidth laser scanner comprises Fig. 9 means 48 for producing a beam of e.m. radiation; a spinner 60 located in the path of the beam to redirect at least a portion of the beam, and at least one hologram secured to the spinner for rotation therewith and positioned to receive the radiation and reconstruct an image e.g. a spot on film 62. Facet surface and angular errors can be tolerated and no lens is needed. In one form Fig. 2 the spinner has a reflecting pyramidal surface 18 surrounded by a transparent cylindrical tube 20 to the outer surface of which is attached a hologram 12 opposite each facet of the pyramid. The hologram 12 is pre-made using an object beam from a point source and a reference beam which beams have similar wavefronts and intersect 12 at the same spatial orientation. In a modification Fig. 3, (not shown) the holograms are sequentially exposed on photo-sensitive material applied to the outer surface of the tube. The object beam falls on the material from outside while the reference beam is reflected from the surface of the spinner (which may be a cone, pyramid or hemisphere), through the tube 20 and on to the material. In another embodiment Figs. 4, 5 (not shown) an axially symmetrical surface is ground into a solid glass cylinder mounted on a rotatable shaft. The surface may be given a reflective coating. Photosensitive material is deposited on the outer surface of the cylinder and the holograms are made as for Fig. 3. In a still further embodiment Figs. 6, 7 (not shown) the photo-sensitive material is applied directly to the surfaces of a six-sided pyramidal spinner. Both object and reference beams arrive from outside the spinner. In a modification Fig. 8, (not shown) a spinner of good quality optical glass is used and the object beam passes through the spinner to interfere with the reference beam from outside to form a thick hologram. Types of holograms which may be used in appropriate embodiments are: thin transmission (amplitude or phase); thin reflection (phase); thick transmission or reflection (amplitude or phase) and blazed (phase). Types of recording materials usable are: silver halide emulsions; dichromated gelatines; thermoplastic-photo-conductor; photo-resist and photopolymer.