An optical heterodyne interferometer with a frequency-ramped laser diode has been constructed. The effect of the beat frequency on the measured phase has been theoretically investigated in the frequency domain and experimentally verified. Phase errors caused by the difference between the ramp frequency and the beat frequency alter sinusoidally in accordance with the π periodicity of the interferogram. The error can be eliminated by the electronic calibration technique of the beat frequency.
© 1996 Optical Society of America
Ribun Onodera and Yukihiro Ishii, "Effect of beat frequency on the measured phase of laser-diode heterodyne interferometry," Appl. Opt. 35, 4355-4360 (1996)