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Shanghai Opto-Mechanical Research Progress in Taiji Phase-Shift Holographic Imaging
[ China Instrument Network Instrument New Product ] Zhang Junyong, the high-power laser physics joint laboratory of Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, for the first time constructed a multifocal phase-shifted Chinese Taiji lens for X-ray phase-shift holography, which was verified in the optical segment experiment. Phase-shifted lensless Fourier transform holographic imaging technology based on Chinese Taiji lens.
Tai Chi lens schematic structure
Due to the objective existence of diffraction limits, one of the most straightforward and simple ways to achieve higher resolution optical imaging is to use light sources with shorter wavelengths. With the rapid development of synchrotron radiation, free electron lasers and nuclear-excited X-ray lasers in recent years, coherent X-rays have been widely used in non-destructive testing of materials, diffraction analysis of crystal structures, and X-ray microscopy.
As a type of diffractive lens, the band plate is difficult to achieve direct imaging of weak phase objects, which is attributed to the fact that the detector can only respond to changes in light intensity. Holography is undoubtedly one of the preferred methods for measuring and imaging many phase objects. The lack of various versatile X-ray devices makes the lensless Fourier transform hologram of the common optical path become a holographic technology applied to the X-ray band earlier, and the optical segment Commonly used phase shift holograms are difficult to achieve in X-rays.
Based on the Chinese Taiji diagram, the research group introduced the diffraction competition concept of yin and yang phase, and designed a kind of Chinese Taiji lens with multi-layer phase-shifted focal spot. It is an amplitude-type diffractive lens suitable for phase-shift X-ray holography. For EUV and longer coherent light bands, phase-diffraction lenses with high diffraction efficiency can be designed to facilitate the detection and imaging of weaker signals. The proposed phase shift holography technique was verified by experiments such as discrimination rate plate and elliptical vortex focal spot.
The research was supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences Youth Innovation Promotion Association. The above related work has been published in the academic journal OpticsLetters (Opt. Lett. 43, 4085, 2018).
(Original title: Progress in China's Taiji phase-shift holographic imaging research in the X-ray band of Shanghai Opto-mechanics)