Due to the improvement in the acquisition speed and stability, single-shot PSH has become a hot topic recently. A research team from Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), has proposed a method of single-shot radial-shearing broadband PSH with assist of a holographic grating and a phase-shifting Fibonacci-sieve array.
Researchers found that the holographic grating as a beam splitter does not need to be calibrated for the introduction of phase shifts or elimination of absolute phase errors, because the phase shifts are only determined by the Fibonacci sieve, and the radial-shearing PSH uses relative phase shifts.
Figure 1 illustrates the principle diagram of the proposed PSH. Figure 2 indicates the experimental results between the Mach–Zehnder setup and our proposed method. The interval between the two rounds of experiments is more than 24h.
Apparently, the result of the double-path shows an unexpected conjugate image, because the OPD between the two paths changes due to the vibration of the system and the environment. After 24h, the OPD of the system has changed and the twin image cannot be eliminated by using the previously set phase shift. Conversely, there is no substantial change in the results of radial-shearing holography and no additional phase shift induced even if the grating is moved, the preset phase shift works well. The comparison of the results shows that the proposed method is more robust than the traditional phase-shift holography. Obviously, the proposed common-path system is high-speed, simple in operation, and insensitive to vibration; hence, it is applicable to real-time measurements with high precision, such as dynamic imaging of the fluctuation of micro-objects, especially living cells.
This research, entitled "Single-shot phase-shifting radial-shearing digital holography with Fibonacci-sieve array irrespective of initial phases" has been published in Applied Physics Letters on June 28, 2021.
This work was supported by National Natural Science Foundation of China, Youth Innovation Promotion Association of the Chinese Academy of Sciences and the Strategic Priority Research Program of Chinese Academy of Sciences.
Fig.1. The schematic diagram of the single-shot phase-shifting radial-shearing digital holography with a Fibonacci-sieve array. (Image by SIOM)
Fig.2. The phase comparison of robustness between two-step phase-shifting holography and our method. (a). Phase distribution of PSH. (b). The differences between the results in (a). (c). Phase distribution obtained by our method. (d). The differences between the results in (c). (Image by SIOM)
Article website:
https://doi.org/10.1063/5.0050681
Contact:
WU Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn
Web: http://english.siom.cas.cn/
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