A sinusoidal phase-modulating (SPM) laser diode (LD) interferometer for real-time surface profile measurement is proposed and its principle is analyzed. The phase signal of the surface profile is detected from the sinusoidal phase-modulating interference signal using a real-time phase detection circuit. For 60*60 measurement points of the surface profile, the measuring time is 10 ms. A root mean square (RMS) measurement repeatability of 3.93 nm is realized, and the measurement resolution reaches 0.19 nm.
© 2007 Chinese Optics Letters
Guotian He, Xiangzhao Wang, Aijun Zeng, and Feng Tang, "Sinusoidal phase-modulating laser diode interferometer for real-time surface profile measurement," Chin. Opt. Lett. 5, 164-167 (2007)