Double exposure ESPI for non-contact surface topography tracking

Hui Wang; Parsa Omidi; Mamadou Diop; Jeffrey J. L. Carson

doi:10.1117/12.2651328

8 March 2023 Double exposure ESPI for non-contact surface topography tracking

Hui Wang, Parsa Omidi, Mamadou Diop, Jeffrey J. L. Carson

Proceedings Volume 12445, Practical Holography XXXVII: Displays, Materials, and Applications; 124450K (2023) https://doi.org/10.1117/12.2651328
Event: SPIE OPTO, 2023, San Francisco, California, United States

Abstract

In this paper, we introduce an electronic speckle pattern interferometry (ESPI) method for rapid assessment of transient deformations on an opaque object. The method records the change in speckle patterns over time, which relate to the change in phase of the reflected light. The system was capable of high-speed recordings enabled by a camera capable of double exposure and external triggering. Experiments were performed on an opaque PDMS phantom to track rapid surface movements from a piezoelectric acoustic driver located at the back of phantom. Acoustic pulses of different period and amplitude were tested. In each double exposure recording cycle, the image pair were digitally subtracted to reveal the change in the speckle pattern, which represented the change in phase of the object beam relative to the reference. We developed custom software to process the data, including an algorithm to unwrap the phase maps. Experiments revealed an ultimate sensitivity to displacements of approximately 1 nm for signals ranging in period from 50 μs to 200 μs. Future work will examine the capabilities of the system with respect to surfaces with different optical absorption and scattering characteristics.

Conference Presentation

Citation Download Citation

Hui Wang, Parsa Omidi, Mamadou Diop, and Jeffrey J. L. Carson "Double exposure ESPI for non-contact surface topography tracking", Proc. SPIE 12445, Practical Holography XXXVII: Displays, Materials, and Applications, 124450K (8 March 2023); https://doi.org/10.1117/12.2651328

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