MULTIPLEX H-2 COHERENT ANTI-STOKES-RAMAN SCATTERING THERMOMETRY WITH A MODELESS LASER

The use of a modeless laser as the Stokes source for multiplex coheren t anti-Stokes Raman scattering in molecular hydrogen is reported. The elimination of noise associated with mode competition in conventional standing wave lasers is shown to result in reliable and accurate singl e-shot thermometry of H-2 in a microwave-assisted diamond chemical vap or deposition plasma reactor. Single-shot temperatures are recorded wi th a precision of 7.3%. Possible improvements to this precision are di scussed and applications of the technique for on-line process monitori ng are briefly presented. (C) 1997 Optical Society of America