Holographic recording and related reading process

[54] HOLOGRAPHIC RECORDING AND RELATED READING PROCESS

[75] Inventors: Jean-Pierre Huignard; Herre Arditty, both of Paris, France

[73] Assignee: Thomson CSF, Paris, France

[21] Appl. No.: 394,723

[22] Filed: Jul. 2, 1982

[30] Foreign Application Priority Data

Jul. 7, 1981 [FR] France 81 13322

[51] Int Cl.< G42B 5/32

[52] U.S. CI 350/3.61; 350/3.64;

350/3.67; 350/3.81; 350/162.2

[58] Field of Search 350/3.64, 3.77, 3.81,

350/3.67, 3.68, 3.85, 162.2

[56] References Cited

U.S. PATENT DOCUMENTS

FOREIGN PATENT DOCUMENTS 2802594 8/1978 Fed. Rep. of Germany 350/3.64

OTHER PUBLICATIONS

Gulanyan et al., "Nondestructive ... Crystals", Sov. J. Quantum Electron., vol. 9, No. 5, May 1979, pp. 647-649.

Huignard and Herriau, "Real-Time ... Configuration",
Applied Optics, vol. 16, No. 7, Jul. 1977, pp. 1807-1809.

Primary Examiner—John K. Corbin
Assistant Examiner—William Propp
Attorney, Agent, or Firm—Cushman, Darby & Cushman

[57] ABSTRACT

A holographic process is provided for recording-reading by means of index strata in the volume of a photoexcitable storage medium. This process consists in causing two beams to interfere in this medium during two successive writing steps by using writing radiations of different wavelengths. The reading of this medium is then effected by means of a third coherent radiation having for wave vector in the medium a linear combination of the wave vectors of said writing radiations.

9 Claims, 9 Drawing Figures