A two-wavelength laser-diode interferometer that is based on heterodyne detection with one phasemeter has been constructed. Two laser diodes are frequency modulated by mutually inverted sawtooth currents on an unbalanced interferometer. One can measure the tested phase at a synthetic wavelength from the sum of the interference beat signals by synchronizing them with the modulation frequency. The experimental result presented shows a phase-measurement range with a 4.7-μm synthetic wavelength.
© 1995 Optical Society of America
Original Manuscript: August 9, 1995
Published: December 15, 1995
Ribun Onodera and Yukihiro Ishii, "Two-wavelength laser-diode heterodyne interferometry with one phasemeter," Opt. Lett. 20, 2502-2504 (1995)