Commissariat a L'energie Atomique

Guy Labrunie

Joseph Borel

Jacques Robert

Engin Molva

Jean-Claude Deutsch

Bruno Dargent

A laser having a volume of less than 1 cubic centimeter comprises a semiconductor constructed to permit the emission of a coherent beam of electromagnetic radiation upon the application of an electron beam to one of its surfaces, and an electron bombardment pumping device for applying the electron beam. The electron bombardment device includes at least one microdot emissive cathode cold electron source having a volume less than 1 cm.sup.3. In a preferred embodiment the laser comprises a plurality of electron bombardment devices formed into a matrix or row of microdot cathodes. A focusing device is provided for focusing the electron beams onto a plurality of excitement strips corresponding to a plurality of semiconductors.

Compact electronic pumping-type semiconductor laser

The invention relates to a method of controlling an optical characteristic of a material and it is concerned also with devices and image-forming means for carrying out the method. The method of control is particularly advantageous in devices comprising a plurality of points distributed in the form of a matrix. The optical characteristic K of the material is controlled by an energization having a magnitude G for a duration t, the values G and t being so selected as a function of the time response K (G, t) of the characteristic K at an energization stage of magnitude G that K (G.sub.O, t.sub.O) is equal to K.sub.O.

Method of controlling an optical characteristic

A method for controlling an optical characteristic of a material which is intercalated between two electrodes driven by periodic excitation signals having a zero mean value consists in applying to the electrodes signals having the same time-duration and the same recurrence frequency but in which one signal has a phase shift .phi. with respect to the other, the phase shift being modified in order to adjust the optical characteristic.

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Seyssinet, France

Guy Labrunie