Optical EngineeringTwo-dimensional rotation angle measurement using a sinusoidal phase-modulating laser diode interferometer
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We propose a simple setup for measurement of a small 2-D rotation angle using a Twyman-Green laser diode interferometer. Sinusoidal phase-modulating interferometry is adopted to detect the phase of the interference signal with a high accuracy and to perform the phase lock to eliminate the phase fluctuation at the standard detection point. By detecting the phases at three points along an axis, the 1-D rotation angle is measured with an accuracy of 0.5 arcsec in the range of 282 arcsec and with a spatial resolution of 3 mm. The 2-D rotation angle measurement is easily made by adding two more detection points.