Laser system

摘要

1,060,055. Lasers. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 17, 1965 [June 25, 1964; June 26, 1964], No. 20844/65. Addition to 1,055,840. Heading H1C. The active medium of a laser is common to. a plurality of optical cavities angularly displaced from each other, an electro-optical light shutter being included in each cavity so that an effective output may be obtained along a single selected light path. As shown in Fig. 1, the active medium 9 may be a spherical solid such as ruby, the medium serving as a lens which directs light between plane mirrors 6a, 6b, 6c and corresponding focal points in a spherical mirror 7. All the light paths 5a, 5b, 5c so defined include.a light shutter comprising a polarizer 20 and a nitrobenzine Kerr cell 15 having electrodes 16, 17, the paths 5b, 5c including, in addition, respective compensators 25, 26 which introduce different degrees of fixed phase delay. As the Kerr cell itself causes a phase delay of polarized light which is related to the potential applied to electrodes 16, 17, all but a selected one of the paths are " Q-spoilt " by appropriate selection of the Kerr cell potential. Either the mirror 7 or the mirrors 6a-6c may be partially light transmitting, and where the various light paths are located in a single plane the active medium need not be fully spherical. In a modification, Fig. 3 (not shown), the mirror 7 is formed as a coating 71 on a part-spherical end surface of an active medium in the form of a cylinder with domed ends. In an alternative arrangement plane reflecting surfaces are formed by facets on the active medium, a Kerr cell being common to all the light paths in Fig. 5 (not shown), while each light path has a respective Kerr cell 17a, 17b in Fig. 4 (not shown). The latter Figure includes a thyratron 31 and associated resistancecapacitance circuit 29, 37, 38 which enables two light paths 5a, 5b to be alternately operable in response to signals applied to a control terminal 33. Polarizers need not be used in the embodiments if the active medium emits polarized light. Two light pumping sources 10, 101, Fig. 1, are described, but as an alternative a helical light tube may be used.