Laser-diode interferometry and phase-conjugate optics

摘要

Laser diodes have been applied to a phase-measuring interferometer with conventional mirrors and a phase-conjugate interferometer with cat mirrors through the wavelength tunability of laser diodes by controlling their currents. Features of the combination of phase shifting and heterodyning by laser-diode modulation in the interferometer with cat mirrors are reviewed. The wavelength is scanned by the laser injection current and is stepwise or rampwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. Cancellation of phase distortions in the interferometer can be performed with wide measurement range. Experimental results are shown.