| 摘要 |
1,208,586. Uses of photochromism. TEXAS INSTRUMENTS Inc. 12 Dec 1967 [31 March, 1967], No. 56398/67. Heading C4S. [Also in Divisions G2 and H4] In making a hologram, a coherent signal 2, Fig. 8, is reflected or transmitted by an object 3 to form an information carrying beam 4 which is split, and the partial beams 115, 116, are recombined at the recording medium 5, e.g. a photochromic material. The coherent signal 2 may be obtained from a laser, maser, or a generator of sound waves, X-rays or microwaves. As shown, light from a laser 1 is passed through lens 9 to object 3 and the beam 4 impinges on a beam splitter 111, the partial beam 116 passing directly to the recording medium 5 and the partial beam 115 being concentrated by lens 112, redirected by mirror 113 and passed through a pinhole 114 to form a partial beam 117 which interferes with the partial beam 116 in the medium 5. In modifications, the lens 112 and pinhole 114 are omitted and the beam splitter may be in the form of a Wollaston prism or diffraction grating. Alternatively the medium 5 may itself form the beam splitter with the portion of the beam which passes through it, or is reflected by its front surface being reflected back by at least one external mirror to interfere with the original beam. Such an external mirror may be integral with the recording medium. If the Fourier transform of the object is to be recorded, the information bearing beam is directed through a lens which is a focal length from the recording medium. In the case of objects separated by a barrier from the light source, light pipes may be used to convey light to and from the object. The information carrying beam may be concentrated by means of a concave mirror before being split. |
