Point diffraction in terference detection technology

Yao, 李瑶 Li; Yongying, 杨甬英 Yang; Chen, 王晨 Wang; Yuankai, 陈元恺 Chen; Xiaoyu, 陈晓钰 Chen

doi:10.3788/co.20171004.0391

Cited by 4 publications

(2 citation statements)

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“…The point diffraction interferometer is well developed [20][21][22]. A near-ideal spherical wave produced by pinhole diffraction is employed as the reference wave surface [23][24][25][26]. That is a plane wave focused by an objective lens and then across a circular aperture [27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Two-Step Converging Spherical Wave Diffracted at a Circular Aperture of Digital In-Line Holography

Tian

Guo

et al. 2022

Micromachines

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The aspheric light emitted from a pinhole restrains the reconstruction quality of a digital in-line hologram. Herein, the Fresnel-diffracted spot from the first step converging spherical wave diffracted at a rough circular aperture is collimated and expanded to generate an even plane wave, which is converged again by an objective lens and matching a minimum aperture while the central spot is varying from light to dark. We observed that the collected background hologram is filled with a round spot with high contrast as an ideal spherical wave. The resolution board and biology experimental results demonstrated a distinctively reconstructed image without any image processing in a single exposure. The adjustable field of view and magnification, single exposure, and noncontact make it suitable for an online microscope.

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Section: Introductionmentioning

confidence: 99%

Two-Step Converging Spherical Wave Diffracted at a Circular Aperture of Digital In-Line Holography

Tian

Guo

et al. 2022

Micromachines

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“…Reference wavefront used in traditional interferometers [1] such as Twyman-Green interferometer and Fizeau interferometer is generated by reflection of a standard reference mirror, so accuracy of the reference wavefront is limited by fabrication accuracy of the standard reference mirror which is usually not better than λ/40 (λ = 532 nm). Different from above interferometers, reference wavefront used in the point diffraction interferometer (PDI) [2][3][4][5][6][7] is generated by a diffraction element called reference wavefront source (RWS). RWS generates a nearly ideal spherical reference wavefront by diffraction at a small aperture of micrometer diameter, so accuracy of the reference wavefront is not limited by a standard reference mirror and can reach sub-nanometer scale.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Fiber-to-Waveguide Couplers in Point Diffraction Interferometer Based on Waveguide Reference Wavefront Source

et al. 2020

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To improve the power of reference wavefront generated by reference wavefront source (RWS) based on silicon nitride (SiN) waveguide in point diffraction interferometer (PDI), we design the Y-branch coupler and grating coupler, and then compare the maximum coupling efficiency, 3 dB fabrication tolerance, 3 dB alignment tolerance and polarization dependent loss of two couplers. Our results show that grating coupler has higher coupling efficiency, lower etching difficulty and alignment difficulty, while Y-branch coupler has lower coating difficulty. To get the maximum efficiency, mode in the fiber must be TE mode no matter for grating coupler or Y-branch coupler. This paper improves the power of the wavefront by selecting appropriate fiber-to-waveguide couplers for waveguide RWS. PDI based on the power improved waveguide RWS is expected to be used in many measurement fields.

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Improved phase-shifting method for pinhole point diffraction interferometer based on a precise driving of the substrate

Lu¹,

Li²,

Zhao³

et al. 2022

Opt. Lett.

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We report a phase-shifting method based on a pinhole point diffraction interferometer. Using the random two-frame phase-shifting algorithm, the piezo electric transducer (PZT) drives the pinhole moving a certain step length along the axis of the tested aspheric mirror. In each step, the CCD collects an interferogram. Then two interferograms are processed by the phase-shifting algorithm. After that, we can acquire the phase map of the interferograms. This technique has great potential for increasing the measuring aperture of the aspheric mirror in the pinhole point diffraction interferometer (PPDI) under the premise of keeping the advantages of PPDI of which the optic devices, as well as error sources, are few behind the substrate.

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Point diffraction in terference detection technology

Cited by 4 publications

References 0 publications

Two-Step Converging Spherical Wave Diffracted at a Circular Aperture of Digital In-Line Holography

Two-Step Converging Spherical Wave Diffracted at a Circular Aperture of Digital In-Line Holography

Comparison of Fiber-to-Waveguide Couplers in Point Diffraction Interferometer Based on Waveguide Reference Wavefront Source

Improved phase-shifting method for pinhole point diffraction interferometer based on a precise driving of the substrate

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