| 摘要 |
1,042,463. Lasers; light modulation. C.S.F.- COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. June 25, 1963 [June 29, 1962], No. 25317/63. Headings H3B and H4F. A laser emits a scanning beam which is deflected by a variable reflecting system adjacent one face of the active medium 1, Fig. 1, the reflecting system comprising a Kerr cell 3 having a non-uniform electric field, a polarizer 6 and a reflecting surface 7. The active medium is pumped by a flash tube 8 and consists of a ruby the transmission face of which is a partial reflector 2. The non-uniform electric field is obtained in the Kerr cell by a plurality of longitudinal grid electrodes g, Fig. 2, having a non-uniform potential gradient, or by the use either of concentric electrodes A, B, Fig. 4, or the equivalent 101, 102 in part-cylindrical form, Fig. 6. These electrodes are connected to a source 50 or 103 of varying potential which permits light transmission to spread progressively across the face of the cell as the potential is reduced. Whenever the light permitted to pass through a region of the Kerr cell exceeds a critical value, stimulated emission takes place in that longitudinal part of the laser active medium receiving the reflected light as indicated by band Zi in Fig. 6. The position of this emission band determines the direction P of laser light transmitted by a lens 51. By using two part-cylindrical Kerr cells arranged orthogonally with respective electrodes 101, 102 and 201, 202, Figs. 8 and 9, connected to separate sources 51, 52 of varying voltage, two intersecting bands Zi, Zj are obtained which effectively permit stimulation to occur only at their intersection. This arrangement enables scanning movements of the emitted light beam to take place by appropriate control of the two voltage sources, the orthogonally-positioned Kerr cells 100, 200 being arranged at opposite ends of the active medium with their axes of symmetry at an angle of 45 degrees to the polarization plane of the emitted light. Quarter wave plates 301, 302 are provided to reverse the controlling action of the variable voltage sources 51 and 52. |
