From Event: SPIE Defense + Commercial Sensing, 2019
A multi-axis heterodyne interferometer concept is under development for observations of five degrees of dynamic freedom using a single illumination source. This paper presents a laboratory system that combines elements of heterodyne Doppler vibrometry, holography, and digital image correlation to simultaneously quantify in-plane translation, out-of-plane rotation, and out-of-plane displacement at the nanometer scale. The sensor concept observes a dynamic object by mixing a single optical field with heterodyne reference beams and collecting these combined fields at the image and Fourier planes, simultaneously. Polarization and frequency multiplexing are applied to separate two segments of a receive Mach-Zehnder interferometer. Different optical configurations are utilized; one segment produces a focused image of the optical field scattered off the object while the other segment produces an optical Fourier transform of the optical field scattered off the object. Utilizing the amplitude and phase from each plane allows quantification of multiple components of transient motion using a single, orthogonal beam.
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James Perea, Brad Libbey, and George Nehmetallah, "Multi-axis heterodyne interferometric for simultaneous observation of 5 degrees of freedom using a single beam," Proc. SPIE 10991, Dimensional Optical Metrology and Inspection for Practical Applications VIII, 109910N (Presented at SPIE Defense + Commercial Sensing: April 17, 2019; Published: 13 May 2019); https://doi.org/10.1117/12.2519292.