| 摘要 |
1,273,410. Holography. SIEMENS A. G. Nov.25, 1969 [Nov. 26, 1968], No.57561/69. Heading G2J. An arrangement for reproducing Lippmann- Bragg holograms wherein the hologram E is illuminated by a light source Q, and a given observer position B o is provided, from which position the line of sight S o is so chosen that the reconstituted image is seen in the zone of optimum sharpness S B , includes means to suppress or substantially reduce any unwanted reflection S r of the light source to the observer position, which reflection would at least partially overlap the image. Preferably the reflection suppressing means is a prism P a which contacts the hologramcarrier H t through an immersion liquid. The wedge angle of the prism may be chosen so that the reconstituted optimum wave S o exits from the prism unrefracted Fig. 7. Desirably a prism of similar geometric proportions contacts the hologram carrier during recording of the hologram. One alternative way of erradicating undesired reflection is to apply a non-reflective coating to the front surface of the hologram. In a further embodiment Fig. 7 the light source Q<SP>1</SP> produces linearly polarised light which is incident on the front face of the hologram at the Brewster angle Y. It is preferred to use a white light source Q a beam of which is split by a polarisation splitter. The reflected polarized component is further reflected to be parallel to the non-deflected component and has its plane of polarisation rotated through 90 degrees. |
