Dynamic wavefront measurement with a pinhole linear polarizer point-diffraction interferometer

Zhou, Xiang; Guo, Ran; Zhu, Weiliang; Zheng, Dong; Chen, Lei

doi:10.1364/ao.56.008040

Cited by 8 publications

(3 citation statements)

References 24 publications

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“…However, its reference wavefront is obtained by using a part of the wavefront to be measured for small aperture diffraction. Introducing a phase shift in the optical path is difficult, and this limits the further improvement of its detection accuracy [14]. In this paper, we use an orthogonal polarization common optical path PDI, which can introduce a four-step phase shift in a single shot in order to obtain high-precision dynamic wavefront measurements.…”

Section: Point Diffraction Interference Systemsmentioning

confidence: 99%

Design and Analysis of Orthogonal Polarization Point Diffraction Pinhole Plate

Han,

Feng,

Zhang

et al. 2024

Photonics

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The pinhole plate is a key component of the point diffraction interferometer (PDI). The reasonable improvement and simulation of this device would enhance the application of point diffraction interferometry technology during the measurement of wavefronts. The traditional point diffraction interferometry measurement method is easily disturbed by environmental noise, making it difficult to obtain high-precision dynamic measurements. This paper introduces a four-step phase-shift PDI that can be employed in a common optical path. By using the principle of the finite-difference time-domain method (FDTD), a simulation model of the orthogonal polarization point diffraction pinhole plate (OP-PDPP) structure is established. The results show that when Cr is used as the film material in the pinhole plate, the parameters include a film thickness of 150 nm, a pinhole diameter of 2 μm, a wire grid period of 150 nm, and a wire grid width of 100 nm; in addition, the comprehensive extinction ratio of the pinhole plate is the greatest and the diffraction wavefront error is the smallest. Finally, the constructed experimental system is used to test the wavefront of a flat sample with a 25.4 mm aperture, and the test results are compared with those of the ZYGO interferometer. The difference in the peak-to-valley (PV) value between the OP-PDI and the ZYGO interferometer measurement is 0.0028λ, with an RMS value difference of 0.0011λ; this verifies the feasibility of the scheme proposed in this paper. The experimental results show that the proposed OP-PDPP is an effective tool for high-precision dynamic measurement.

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Section: Point Diffraction Interference Systemsmentioning

confidence: 99%

Design and Analysis of Orthogonal Polarization Point Diffraction Pinhole Plate

Han,

Feng,

Zhang

et al. 2024

Photonics

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“…As an advanced technique for high-precision optical metrology, phase-shifting interferometry (PSI) plays important roles in optical shop testing, 1 laser wavefront diagnosis, 2 and threedimensional shape measurement, [3][4][5] among others. In standard PSI, multiple interferograms with known phase steps (typically, e.g., p=2 rad) are required to extract the underlying phase related to the physical quantities to be measured.…”

mentioning

confidence: 99%

“…Figure 1(e) shows the CVs of the retrieved modulation terms [Eqs. (2) and 3] using different phase steps based on the interferograms in Figs. 1(a) and 1(b).…”

mentioning

confidence: 99%

Random two-frame phase-shifting interferometry via minimization of coefficient of variation

Cheng

Liu

Zhang

2019

Applied Physics Letters

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Random two-frame phase-shifting interferometry (PSI) is an advanced technique to retrieve the phase information from as few as two interferograms with unknown phase steps. Because of the advantages of no requirement for accurate phase shifters and much less time for data acquisition and processing, random two-frame PSI is attracting more and more interest in fast and high-precision optical metrology. However, reconstructing the phase from only two interferograms is challenging because it is an ill-posed problem in essence, especially when the phase step is unknown. Although some solutions have been proposed for this problem to date, most of them require complicated preprocessing or special usage preconditions for interferograms to be demodulated. In this letter, we developed an elegant phase reconstruction method for random two-frame PSI, which is much different from frameworks of existing methods. In the proposed approach, the phase of random two-frame PSI can be accurately reconstructed using the phase step value which minimizes the coefficient of variation (CV) of the modulation term of interferograms. Sufficient numerical simulations and experimental data demonstrate the high accuracy and high efficiency of this CV minimization (CVM) method. Moreover, its performance is not limited by the number of fringes in interferograms, in contrast to existing state-of-the-art approaches. We anticipate extensive applications of the CVM method in random two-frame PSI in the future.

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