GB1289095A - - Google Patents

Abstract

1289095 Holography AGFA-GEVAERT N V 25 Sept 1969 [2 Oct 1968] 46847/68 Heading G2J A hologram is recorded in a medium 10 in optical contact with one face 11 of a prism, a reference beam 14 and an object beam 16 each entering the prism through different faces 12, 13, which faces are also different from that in contact with medium 10. Preferably the reference beam is totally internally reflected on at least one prismair interface, e.g. the face 13 before reaching the recording medium 10. The reference beam falls on the recording medium 10 at an angle of incidence greater than the critical angle of the medium/ air interface. To prevent interference by total internal reflection the medium contains absorbing dyes which are bleached out when the hologram is developed. In another embodiment to prevent aberration a second prism 22 is located in the object beam path, whereby the object beam enters prism 22 through a face parallel to the recording layer and the exit face is parallel to the entry face of the first prism. If desired the recording medium 20 may be in contact with the prism through a liquid, gaseous or adhesive interlayer 21. The prisms may be any desired shape. In reconstructing an image a reconstruction beam is used which follows the same path relative to the hologram as the reference beam and so forms a vertical image, the reconstruction beam being totally internally reflected as shown by broken lines.