Abstract

An unexpected phenomenon has been observed which triggered an investigation into the lensing effect of a CO₂ laser plasma. This effect, so far thought to be negligible in a conventional CO₂ laser of, for example, 2-m length, produces a focal length in the order of magnitude of −20 m. In view of this experimental observation, the focal length of the plasma lens, as well as the stability condition for an optical resonator with a plasma lens within its plane concave mirror system, are determined and expressed in terms of plasma and resonator characteristics as well as of the electrical power dissipated in the plasma. The analysis reveals that the semiconfocal configuration is most adverse for a frequency-stabilized laser. The overall result of this investigation suggests that the optimum configuration of a conventional CO₂ laser for maximum output power is obtained when the negative focal power of the plasma lens precisely compensates for the positive focal power of the slightly curved mirror.

© 1970 Optical Society of America

Plasma Self-Q Switching in Far Infrared Lasers

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Low Voltage CO₂ Laser Excitation

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A Scanning Spherical Mirror Interferometer for the Analysis of CO₂ Laser Radiation

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