A two-wavelength sinusoidal phase-modulating (SPM) laser diode (LD) interferometer for nanometer accuracy measurement is proposed. To eliminate the error caused by the intensity modulation, the SPM depth of the interference signal is chosen appropriately by varying the amplitude of the modulation current periodically. Then, the refine theory is induced to the measurement, and the two-wavelength interferometer (TWI) is combined with the single-wavelength LD interferometric technique to realize static displacement measurement with nanometer accuracy. Experimental results indicate that a static displacement measurement accuracy of 5 nm can be achieved over a range of 200 \mu m.
© 2012 Chinese Optics Letters
(070.6020) Fourier optics and signal processing : Continuous optical signal processing
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(350.2460) Other areas of optics : Filters, interference
Instrumentation, Measurement, and Metrology
Bofan Wang, Zhongliang Li, and Xiangzhao Wang, "Two-wavelength sinusoidal phase-modulating interferometer for nanometer accuracy measurement," Chin. Opt. Lett. 10, 071202-071202 (2012)