| 摘要 |
1,157,735. Holography. RADIO CORPORATION OF AMERICA. Aug. 16, 1967 [Sept. 15, 1966], No.37629/67. Heading G2C. In an arrangement for making a hologram on a medium 22, a source of coherent light is positioned in front of an expander to provide a parallel-ray single beam, one portion 18 of which is used as the reference beam and the other portion 24 of which impinges on a light diffuser 26 and the object 28 to be hologrammed. The source may be a laser 10 whose output is focused by lens 12 at a pinhole in element 14 which is at the focus of a lens 16, the light being polarized in a plane parallel to surface 37 of diffuser 26 to minimize reflection losses. The diffuser 26 is at an angle α to the incident beam and consequently the principal component of the emitted light is not in the direction towards the medium 22. To obviate this, the diffuser may be in the form of a deflecting prism (32, Fig. 2, not shown) which deviates a parallel ray of the beam towards the medium (22) the rear surface (34) of the prism being roughened to form a diffuser. All the apparatus may be mounted on an aluminium slab supported on a bed of sand which is itself supported on two further beds of sand to avoid vibrations being communicated to the apparatus. It is shown in the Specification that since the maximum difference in length between the path taken by the reference and information beams d - b is quite small, e.g. 13 mm., it is possible to use cadmium or mercury light sources instead of lasers if the pinhole diameter is about 2 microns. |
