Paper
27 January 2023 Extended focusing in dual-wavelength digital holography
Sibing Hou, Haiyu Zhang, Bole Ma, Ping Cai, Jiamiao Yang, Hao Yan
Author Affiliations +
Proceedings Volume 12550, International Conference on Optical and Photonic Engineering (icOPEN 2022); 1255010 (2023) https://doi.org/10.1117/12.2667078
Event: International Conference on Optical and Photonic Engineering (icOPEN 2022), 2022, ONLINE, China
Abstract
Dual-wavelength digital holography (DH) extends the depth range of measurement, but it faces an issue that it can’t focus the whole extended depth range. In single-wavelength DH, the depth of focus of a correct reconstruction distance is usually sufficient to cover the whole depth range. Therefore, in single-wavelength DH, autofocusing algorithms which can obtain a correct reconstruction distance have been proposed and can solve the issue of focusing the whole depth range. But in dual-wavelength DH and even multi-wavelength DH, the extended depth range of the measurement often spans multiple depths of the focus of the optical system, which means that the depth of focus of a single reconstruction distance is not capable to cover the whole extended depth range, making part of depth out of focus. Therefore, in dual-wavelength DH, only autofocusing is not enough but extended focusing is demanded. However, we lack extended focusing approaches in dual-wavelength DH. Therefore, we propose an extended focusing approach based on correlation coefficient (CC) to focus the whole extended depth range in dual-wavelength DH. The proposed approach includes three steps: (1) dividing the extended depth range by the depth of focus of the system; (2) using the CC-based autofocusing approach to find the correct reconstruction distance of each divided region and reconstructing this region; (3) concatenating reconstructed image of each region and constituting the whole-depth-focused image. Through simulation experiments and practical experiments, the effectiveness and necessity of the proposed approach are verified.
© (2023) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sibing Hou, Haiyu Zhang, Bole Ma, Ping Cai, Jiamiao Yang, and Hao Yan "Extended focusing in dual-wavelength digital holography", Proc. SPIE 12550, International Conference on Optical and Photonic Engineering (icOPEN 2022), 1255010 (27 January 2023); https://doi.org/10.1117/12.2667078
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KEYWORDS
3D image reconstruction

Digital holography

3D image processing

Correlation coefficients

Image restoration

Image sensors

3D metrology

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