This contribution introduces a novel approach for phase retrieval of smooth surfaces based on parameter estimation in the two beam interference equation. Perturbation resistance is achieved, by sampling of the required interference images in separated color channels of a 3-Chip-CCD camera, using pulsed LED illumination with pulse width and interval in the range of microseconds. Therefore, two interference images are captured with an extremely short delay compared to the camera frame rate, making the measurement quasi single-shot with respect to low frequency perturbations. An optical path difference is introduced to one of the recorded images, by an oscillating mirror in the reference path. This is required to determine the correct sign of the retrieved phase. The theory of phase reconstruction based on the two beam interference equation is outlined in detail. Experimental results are presented, which indicate a strong influence of dispersion effects on the achievable results.
Markus Schake and Peter Lehmann, "Perturbation resistant RGB-interferometry with pulsed LED illumination," Proc. SPIE 10678, Optical Micro- and Nanometrology VII, 1067805 (Presented at SPIE Photonics Europe: April 25, 2018; Published: 24 May 2018); https://doi.org/10.1117/12.2306221.
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