Patent ID: 6111670
Filing Date: 2000-08-29
Classification: G02B,G03H

Abstract:
A method for producing a hologram comprising:generating a reference light;generating an object light passed through a light diffusing body;and exposing a photo-sensitive member by the reference light and the object and the object light so that interference occurs so that a diffraction grating corresponding to the light diffusing body is recorded on the photo-sensitive member;the size of the light diffusing body being such that the hologram has a spectral characteristic of a diffused light from the hologram such that, in at least the wavelength range of visible light, a desired efficiency is obtained;wherein the desired size of the light diffusing body which allows the hologram to have a spectral characteristic of a diffused light is of such a size that a difference m between the length S of a side of the light diffusing body and the length M of a side of the photo-sensitive member satisfies the following equation:m=S-M=S.sub.1 +S.sub.2 ;S.sub.1 .gtoreq.L.times.tan(sin.sup.-1 ((sin .theta..sub.1 -sin .theta.c).times.(.lambda..sub.0 /.lambda..sub.c2)+sin .theta.r)-M.sub.1, andS.sub.2 .gtoreq.L.times.tan(sin.sup.-1 ((sin .theta..sub.1 -sin .theta.c).times.(.lambda..sub.0 /.lambda..sub.c1)+sin .theta.r)-M.sub.2,Where:.theta.r is an incident angle of the reference light to the photo-sensitive member;.theta..sub.0 is an incident angle of the object light from the light diffusing body introduced into the photo-sensitive member;.theta.c is an incident angle of the regenerating light introduced into the hologram as produced;.theta..sub.I is an exit angle of the diffraction light from the hologram.lambda..sub.0 is a wavelength of the laser beam during the recording;.lambda.c is a wavelength in the diffracted direction .theta..sub.i, where .lambda.c is in a range .lambda..sub.c1 to.lambda..sub.c2 and .lambda..sub.c1 is 380 nm and .lambda..sub.c2 is 780 nm;L is a distance between the light diffusing body and photo-sensitive member during a recording to the photo-sensitive member;S.sub.1 is a difference in length between the light diffusing body and the photo-sensitive member on the side adjacent the inlet side of the reference beam;S.sub.2 is a difference in length between the light diffusing body and the photo-sensitive member on the side opposite the inlet side of the reference beam;M.sub.1 is a distance between an end of the photo-sensitive member adjacent the inlet side of the reference light and a point A on one of the photo-sensitive member and the hologram where the reference light is introduced, and;M.sub.2 is a distance between an end of the photo-sensitive member opposite to the inlet side of the reference light and the point A.