Far-infrared radiation generated from the difference frequency between two temperature-tuned ruby lasers has been observed over the frequency range from 1.2 to 8.1 cm^-1. Lithium niobate and quartz were used as mixing crystals. The conversion efficiency was measured as a function of angle around the phase-matched direction. The expected spectral content and frequency of the far-infrared radiation has been verified using a far-infrared Fabry-Perot interferometer.
No takes yet. Share an insight, caveat, or question.
Faries et al. (1969) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: