Optoacoustic frequency stabilization of a carbon dioxide laser

Abstract

In this thesis a study has been made of the design, construction and, in particular, frequency stabilization of a d.c. excited carbon dioxide laser. The outline of the theory of the carbon dioxide laser is presented as a prelude to a detailed study of optogalvanic and optoacoustic effects. Experimental investigations have been made of both of these phenomena, and the results used for frequency stabilization of a conventional large tube diameter flowing gas type of carbon dioxide laser. A special feature of the work is intra-cavity optoacoustic detection of laser power by carbon dioxide gas absorption within the laser tube itself but outside the plasma region, for a new method of frequency stabilization. It is shown experimentally that this novel method is superior to the well established optogalvanic technique of frequency stabilization, in terms of signal to noise ratio and short response time.
Extension of the intra-cavity optoacoustic method to both d.c. and r.f. excited waveguide lasers is discussed.