Self-heterodyne detection of backscattered radiation in single-mode CO₂lasers

Self-mixing detection of backscattered radiation in single-mode pulse-periodic CO2 lasers

“…We based our theoretical analysis on the model suggested by Gordienko, et al [4] for the self-mixing effect in continuously pumped CO 2 lasers, which adequately describes the amplitude-frequency characteristic (AFC) of autodyne amplification, the depth of modulation, and also the nonlinear distortions of the autodyne signal in the case of high backscattering/reflection levels. In the case of short distances from the output mirror to the scattering object that allow the variation of the instantaneous resonator frequency during the delay time of the echo signal to be disregarded, the equations for the given model of the self-mixing effect effect in CO 2 lasers have the form [4] …”

“…In the case of short distances from the output mirror to the scattering object that allow the variation of the instantaneous resonator frequency during the delay time of the echo signal to be disregarded, the equations for the given model of the self-mixing effect effect in CO 2 lasers have the form [4] …”

“…These lasers have a high spatial beam quality at high average output power. Gordienko, et al [4] theoretically and experimentally studied the autodyne effect in single-mode, continuously pumped CO 2 lasers in a wide range of levels of backscattered/reflected radiation. Their investigations have shown that the self-mixing effect in a single-mode CO 2 laser is sufficiently stable to high levels of backscattering [4].…”

“…Gordienko, et al [4] theoretically and experimentally studied the autodyne effect in single-mode, continuously pumped CO 2 lasers in a wide range of levels of backscattered/reflected radiation. Their investigations have shown that the self-mixing effect in a single-mode CO 2 laser is sufficiently stable to high levels of backscattering [4]. This opens the possibility of using the autodyne effect in the problems of remote and online monitoring of destructive action of laser radiation on condensed media, in particular for diagnostic and control of tissue ablation by radiation of CO 2 lasers and for monitoring of laser materials processing.…”

“…The autodyne regime is of great practical importance and is used for solving such problems as speed measurements [1,2], small oscillation detections, distance measurements [2], and atmospheric gas analysis [3]. For intracavity detection of reflected or scattered radiation, one uses semiconductor [2], solid-state, gas lasers [1,4], and, more recently, diodepumped chip lasers [5] and fiber lasers [6].…”