GB1488937A - Lasers - Google Patents

Abstract

1488937 Lasers MAX - PLANCK - GES ZUR FODERUNG DER WISSENSCHAFTEN eV 27 Feb 1975 [1 March 1974 (2)] 8209/75 Heading H1C Laser output pulses are obtained by the photolysis of a gaseous compound of iodine which is combined with a buffer gas in a brewster-windowed container 1 at a total pressure of at least 80 Torrs, the photolysative decomposition and consequential population inversion of the freed iodine atoms being effected by a flash lamp producing substantial ultra-violet radiation in its output spectrum. The flash lamp is annular and is fired by triggering a spark gap 5, the duration of the pumping radiation being restricted to about 2 Ás to prevent self-excitation of the laser. The laser resonator is formed by a concave mirror 2 and plane mirror 3, the output modes being limited by diaphragms 4 and 6. A laser amplifier using the same iodine compound and buffer gas mixture in a container 11 may be included in the output path which includes a filter 9 for rejecting pumping light frequencies. The amplifier is pumped by a flash lamp 10 located in an elliptical reflector 13, the lamp being triggered by a spark gap with a delay of about 1 Ás relative to the firing of the laser generator. Output monitoring is effected by measuring devices 8 respectively coupled to the generator and amplifier outputs, by beam splitters 7. A further measuring device 15 is also provided. Both lasers are coupled to the same gas source through a gas circulating system which comprises a pressure gauge 16, valves 22, a cooling trap 20, a diffusion pump 21, and tanks 17, 19 containing the laser active iodine gas and the buffer gas, respectively. Tanks 18 are provided for forming the gas mixture required. The laser active iodine gas may be C 2 F 5 I, CF 3 I, perfluorine-tertiary butyliodine (t - C 4 F 9 I) or perfluorine - isopropyl iodide (i-C 3 F 7 I). The fluorine may be completely or partially replaced by bromine and/or chlorine. The buffer gas may be sulphur hexafluoride (SF 6 ), argon or CO 2 . The partial pressure of the iodine gaseous compound may be between 5 to 70 Torrs and the partial pressure of the buffer gas must exceed 30 Torrs and may reach 10 atmospheres.