A lateral super-resolution differential confocal technology with phase-only pupil filter |
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Authors: | Lirong Qiu Zhengde Feng Xuemei Ding |
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Affiliation: | Automatic Measurement and Control Engineering Department, Harbin Institute of Technology, P.O. Box 718, Harbin 150001, P.R. China |
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Abstract: | In order to achieve a higher lateral resolution required for ultraprecision measurement of microstructural workpieces, phase-only pupil filtering differential confocal microscopy (PFDCM), a new approach is proposed based on the differential confocal microscopy (DCM), which uses a three-zone phase-only pupil filter with lateral super-resolution capability obtained through optimized design to change the distribution of DCM three-dimensional point spread function, so that the DCM lateral resolution is therefore significantly improved while its axial resolution is slightly improved. Preliminary experimental comparison and analyses indicate that, the lateral and axial resolutions of PFDCM are better than 0.2 μm and 2 nm, respectively, when wavelength of incidence laser beam , numerical aperture of measuring lens NA=0.85, and lateral spot size with a three-zone phase-only pupil filter GT=0.65. It is therefore concluded that PFDCM is a new approach to further improvement of lateral resolution in laser probe measurement systems. |
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Keywords: | Super-resolution Confocal microscope Phase-only pupil filter Surface contour Laser probe |
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