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

Abstract

Powerful 48-and 57-µm CH 3 OD lasers pumped by a 9R(8) CO 2 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 48-and 57-µm CH 3 OD 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 48-and 57-µm laser interferometer system.

Electron concentration in the non-luminous part of the atmospheric pressure filamentary discharge

“…However, the recent advances in microwave technology (especially availability of coherent sources at THz frequencies) and computational power brought a renaissance of microwave techniques. Smaller wavelengths [21][22][23] give better spatial resolution and higher cut-off frequencies (i.e. the measured plasma density could be higher).…”

Stabilization of 48- and 57-μ m CH3OD lasers for plasma diagnostics

“…Atmospheric absorption of FIR light by water vapor is one of severe problems for beam transitions. The absorption of the 48-and 57-µm lasers is larger than that of the 119-µm laser [4]. This application requires that the two-color FIR laser should be a powerful and stable for a long time.…”