Two noncollinear coherent light waves interfering inside a semi-insulating semiconductor form an optical pattern (grating). Transient photoelectromotive force (photo-EMF) current can be generated when the phase of the grating is changed. Attractive features of the photo-EMF technique include ruggedness and comparative simplicity of system setup and signal processing. It has been successfully incorporated in vibrometry, displacement measurement, etc. We report a novel scheme for wide range and the high-resolution displacement measurement with photo-EMF effect that requires no moving component or complicated signal processing.
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