Development of Short-Wavelength Far-Infrared Lasers and Optical Elements for Plasma Diagnostics

Abstract

Powerful 48and 57-μm CH3OD lasers pumped by a 9R(8) CO2 laser have been developed to establish a new two-color FIR laser interferometer system for high density and large volume plasma diagnostics. To design the collimated beams for the interferometer, the beam profiles and the divergence angles have been measured for the 48and 57-μm CH3OD lasers oscillated simultaneously. Water vapor absorptions for the laser wavelengths have been measured at 22 ◦C to realize an efficient transmission line. Optical constants and transmittance and reflectance of crystal quartz, silicon, CVD-diamond, polyethylene sheet, Mylar film, TPX plate, metal mesh and wire grid have been measured to design the optical components (observation windows and beam splitters) in the 48and 57-μm laser interferometer system.