Highly sensitive shearing interferometer.
A shearing type scanning interferometer is presented. The polarization modulation technique and homo-dyne detection of the first harmonic component of intensity carrying information about a phase shift between interfering beams were used. The interferometer has a variable measuring range, max +/- lambda/4, and sensitivity of the order of lambda/10,000. The modulator is based on the Faraday cell making possible a simple calibration of the interferometer. Measurement results of the refractive-index profile in optical fibers are presented. A detailed analysis of the systematic errors of the interferometer is also performed.
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