GB1420932A - Lasers - Google Patents

Abstract

1420932 Combustion apparatus of detonation type ROLLS-ROYCE (1971) Ltd 18 Jan 1973 [26 Jan 1972] 3801/72 Heading F1L [Also in Division H1] Laser radiation is produced by associating an electromagnetic wave resonator with a closed loop combustion channel in which at least one combustion-initiating detonation wave is circulated. The combustion channels are of the type described in Specifications 1069217 and 1213551, Figs. 1a, 1b, and 1c, respectively, and comprise a closed loop combustion chamber 19, 1 supplied with the mixture of an atomized fuel such as kerosene, and a pressurized gaseous reactant such as air, to produce laser action based on carbon dioxide, carbon monoxide or water transitions. The combustion chamber includes a detonation starter 31, and in Figs. 1a, 1b the fuel and reactant gases are passed into the chamber 19 between baffles 27 while the combustion gases are expelled between baffles 28. In Fig. 1c the combustible gases are introduced through ducts 2, 3 and the combustion gases expelled through a convergentdivergent nozzle 5. Several detonation waves may be circulated in the closed loop channel at the same time, Fig.2 (not shown). Stimulated emission may be obtained in the combustion gases behind a detonation wave, in which case infrared transmissive windows 9, Fig. 3c, and 11, Fig.4, are provided in the channel walls along the axis of the resonator. In Fig. 3c the resonator is formed by a mirror 7 and an apertured or partiallytransmissive output mirror 8, and its axis is transverse of the channel 1, while in Fig.4 the resonator formed by mirrors 12, 13 is elongated by arranging its axis to extend along a linear portion 10b of the closed loop channel 10. In an alternative arrangement the laser energy is obtained by expansion of the combustion gases from a nozzle 5, Fig. 3b, the resonator 7, 8 being arranged downstream of the nozzle and transverse of the gas flow. In a ring laser modification, Fig.5, the closed loop channel 16 has linear portions 16a-16d having nozzles directed towards a closed optical path formed by mirrors 14, 15. A further arrangement, Figs. 6b, 6c, comprises a closed loop channel the elongate portions 18a, 18b of which each comprise a respective nozzle directed in common to a region 21 along the optical axis, 25 of a resonator formed by mirrors 23, 24.