Rapidly tuning miniature TEA CO2 laser - rotating mirror and grating mechanism

In this research, directed toward using differential absorption lidar (DIAL ) for measuring concentrations of pollutant gases, a device for rapidly tun ing a transversely excited atmospheric-pressure (TEA) CO2 laser is presente d. It is shown that it is possible to utilize a rotating six-sided scanning mirror and a fixed diffraction grating to rapidly switch wavelength over r andomly selected lasing transitions in the 9-11 mu m region of the spectrum . The scanning mirror and an optical encoder ale driven by a hysteresis syn chronous motor at a speed of 1500 rpm. A surface-wire-corona preionization was utilized in a cavity. The laser system is highly automated with micropr ocessor-controlled laser line selection. Single-branch emission at two wave lengths with time interval less than or equal to 10 ms has been obtained fr om a single cavity TEA CO2 laser. An accurate line selection has been demon strated in over 40 transitions at a pulse repetition frequency of up to 100 Hz. The laser energy at first-order couple output was up to 20 mJ per puls e and the pulse width is about 60 ns in an active volume of 36 cm(3). (C) 2 000 Elsevier Science B.V. All rights reserved.