A Novel Approach for Measurement of Free-Form Optical Elements with Digital Holographic Microscopy

Zhang, Xuhui; Wu, Chonglin; Chen, Lei; Chen, Gengliang; Zheng, Guoliang

doi:10.3390/mi13101719

Cited by 1 publication

(1 citation statement)

References 24 publications

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“…Digital holography (DH) has become a rapidly developing technique for 3D shape measurement in recent years and is increasingly used in the fields of microscopic imaging [1,2], microstructure surface measurement [3], and living cell analysis [4,5]. Slightly off-axis digital holography (SODH) has gained increased attention because it is faster than on-axis DH in reconstructing images and achieves better resolution of reconstructed images than off-axis DH.…”

Section: Introductionmentioning

confidence: 99%

Slightly Off-Axis Digital Holography Using a Transmission Grating and GPU-Accelerated Parallel Phase Reconstruction

Bai,

Chen,

Sun

et al. 2023

Photonics

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Slightly off-axis digital holography is proposed using transmission grating to obtain quantitative phase distribution. The experimental device is based on an improved 4f optical system in which a two-window input plane is used to form the object beam and reference beam. Then, the two beams are diffracted into multiple orders by the transmission grating placed at the Fourier plane. By applying a modified Michelson configuration, the interference patterns can be generated by the object and reference beams from different diffraction orders. After translating the grating, a random phase shift can be introduced to the hologram. To demonstrate the feasibility of our method, both thick and thin phase specimens are retrieved using two carrier phase-shifting holograms. Furthermore, we use the phase reconstruction algorithm based on the NVIDIA CUDA programming model to reduce the retrieval time. Meanwhile, we optimize the discrete cosine transform (DCT)-based least-squares unwrapping algorithm to unwrap the phase. By porting the entire phase reconstruction process to the graphics processing unit (GPU), the phase retrieval acceleration and execution efficiency significantly improve. To demonstrate the feasibility of our method, it is found that our method can measure the surface profiles of standard elements, such as a plano-convex cylinder lens and a microlens array, with a relative error of about 0.5%. For holograms with a different phase shift, the root-mean-square (RMS) value of the phase difference for the main imaging region is about 0.2 rad. By accelerating the phase reconstruction with GPU implementation, a speedup ratio of about 20× for the thick phase specimen and a speedup ratio of about 15× for the thin-phase specimen can be obtained for holograms with a pixel size of 1024 × 1024.

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