| 摘要 |
1,081,011. Lasers. GENERAL ELECTRIC CO. Aug. 20, 1964 [Sept. 4, 1963; Sept. 25, 1963], No. 34137/64. Heading H1C. In a laser a disc of laser active material and a light pumping source are positioned in a housing having a reflective inner surface so that the end surfaces of the disc are pumped. In the arrangement shown in Fig. 1 a disc 1 of neodymium doped lanthanum borate glass is supported in a metal housing 2 with its longitudinal axis perpendicular to the longitudinal axis of the housing 2 and aligned with apertures 4, 5. A plurality of lamps 8 are disposed adjacent each other to form a plane passing through the centre of the disc 1 and adjacent lamps are separated by reflector members 10 which direct the lamps' radiation toward particular areas of the reflective inner surface of housing 2 and thence to one or both of the end faces of disc 1. If the lamps are flash operated the reflectors 10 also function as trigger electrodes. The terminals and wires are brought out through removable panels 7 in end walls 6. If the housing is elliptical the lamp-reflector plane and the laser disc are positioned at the conjugate focii of the ellipse. A selective radiation filter may be provided between the lamps and disc to reduce heating of the disc or forced air or liquid coolants may be provided. The end faces of disc 1 are coated with a low reflection coating and need not be optically flat, and the housing is contained in an optical cavity formed by a plane mirror and a prism, Fig. 3 (not shown). In the embodiment of Fig. 2 the housing 2 is a sphere and the lamps 8 are curved. A glass filter 33 divides the housing into two parts. The disc-shaped laser members may be of generally square or rectangular cross-section, Fig. 3 (not shown). In Fig. 4 (not shown) a plurality of housings (2) and associated apparatus are arranged in an optical cavity and optically coupled to adjacent housings so as to provide an oscillator. The oscillator of Fig. 5 offers a higher degree of mode selection than that of Fig. 4 and comprises a plurality of housings 2 arranged between two crossed Porro prisms 15 and 16. The energy is extracted from the cavity by means of partially reflective mirror 17 and prism 18, and mode selection is achieved by rotating prisms 15, 16 about the axis defined by the roof edge 19 so that the on-axis mode falls within the critical angle of the total internal reflective surfaces formed by the prism and the off-axis modes are not reflected. In an amplifier, Fig. 6 (not shown), a Q-switched laser oscillator (30) has its output amplified by a chain of lasers in housings (2), no optical cavity being provided in this case for the single pass lasers. The lasers shown in Figs. 1, 2, 3 may be pulse operated or continuously operated. The reflective inner surfaces of the housing may comprise a plurality of small flat mirrors to provide controllable focusing of the lamps' radiation upon the end faces of the disc. Ruby can be used as the active material and the cross-section of the disc need not be circular, other configurations being disclosed. |
