A large field of view measurement method for surface topography of microspheres based on microscopic interferometry

Abstract

The invention discloses a method for measuring microsphere surface topography with a large field of view based on micro-interference. Four-step phase-shifting method and unwrapping to obtain its surface topography distribution; for the defocused blurred imaging area in the microscope imaging field of view, first calculate the test light field distribution of the CCD surface, and then calculate the image of the microspheres imaged by the microscope The surface is divided into a series of inclined micro-surface elements, and then the focus phase distribution of each surface element is calculated by inverse diffraction calculation and combined to obtain the phase distribution of the entire image surface, and then the actual microsphere surface of the blurred imaging area is obtained from the object-image relationship Morphology distribution; finally, the clear imaging area and the fuzzy imaging area are stitched together to obtain the microsphere surface morphology distribution within the entire field of view. The invention can realize the measurement of the surface topography of the microsphere in a single large field of view, and is beneficial to improving the measurement efficiency of the entire surface of the microsphere.

Description

technical field [0001] The invention relates to the field of precision optical measurement engineering, and more specifically, to a method for measuring microsphere surface topography with a large field of view based on microscopic interference. Background technique [0002] The traditional surface topography measurement method adopts point-by-point scanning method, which has low detection efficiency and low lateral resolution, and is easily affected by environmental vibration, temperature and humidity changes, etc., and is easy to scratch the surface of the component. It mainly includes various profilers, atomic force microscope (AFM) and so on. Initially in China, the atomic force microscope was mainly used to observe the surface of the target capsule, and a relatively accurate surface profile of the target capsule was obtained, but it could only obtain local information on the surface of the target capsule. Optical interferometry has the advantages of non-contact, high s...

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Problems solved by technology

[0005] Wei Cong and others from Nanjing University of Science and Technology used zero interferometric microscopy to achieve high-precision measurement of the surface morphology of microspheres with different diameters in the article "Null interferometric microscope for ICF-capsule surface-defect detection", but they used large values The aperture of the microscope, which corresponds to a shallow depth of field, limits the effective measurement range in the microscope imaging field of view, and its effective range is only located in the central clear imaging area

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