Two mode internally reflective laser for length measurement - has wavelength absolute controlled by measuring mode intensities for absolute frequency valve

摘要

To control the absolute value of the frequency of a two mode internally reflective laser using a filler gas mixture of helium and isotope containing Neon the difference in intensity of the modes is measured, and the calibration measurement of the frequency of the actual absolute value of the laser frequency is determined. For the laser mirror, isotope reflectors with R less than 0.1 percent are used. The mode intensities are separated by a polariser and measured and with a photoreceiver followed by an electronic display. ADVANTAGE - High absolute accuracy.