1 August 1975 Sensitivity Improvement by Step-Biasing in Holographic Interferometry
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A technique of holographic interferometry yielding a one-order-of-magnitude increase in sensitivity over conventional techniques is described. The method, based on the superposition of a calibrated quarter-wavestep motion on the motion to be detected, is designated as step-biasing. The sensitivity improvements are due to a reversal of the brightness distribu-tion, so that vibrating points appear lighter, nodal points darker. A theoretical discussion of the technique, as applied to the detection of vibration by time-average holographic inter-ferometry, is offered and experimental verification with a 30A peak amplitude of vibration is presented, together with comparison with conventional techniques. The method was originally devised for application to real-time holographic interferometry. This is done easily, yielding the same sensitivity improvement.
Mauro H. Zambuto, Amin Hanafy, "Sensitivity Improvement by Step-Biasing in Holographic Interferometry," Optical Engineering 14(4), 144372 (1 August 1975). https://doi.org/10.1117/12.7971847 . Submission:

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