Zhejiang University

Yongying Yang

Yang Li

Dong Liu

Jian Bai

Fan Wu

Pin Cao

Fanyi Wang

Weimin Lou

Yubin Du

Pan Guo

Kaiwei Wang

Shiwei Chen

Huiting Chai

Yibing Shen

In a real-time traceability method of a width of a defect based on divide-and-conquer provided by the present invention, through the calibration transfer function, the multidimensional eigenvector analysis technology based on the electromagnetic field simulation database of defect scattered dark-field imaging and the adaptive threshold segmentation method, the real-time traceability of the width of the defect greater than and close to the diffraction limit of the system is performed, respectively. The extreme random tree regression model is trained by multidimensional eigenvector analysis technology based on the multidimensional eigenvectors in the electromagnetic field simulation database of the defect scattered dark-field imaging. The present invention solves the problems that the width of the defect in defect detection is difficult to be accurately measured in real time, and the conventional image processing algorithm is difficult to accurately identify the width of the defect close to the diffraction limit of the system.

Real-time traceability method of width of defect based on divide-and-conquer

A defects evaluation system and method are provided in the present invention. Based on the principle of the microscopic scattering dark-field imaging, the present invention implements a sub-aperture scanning for the surface of spherical optical components and then obtains surface defects information with image processing. Firstly, the present invention takes full advantage of the characteristic that the surface defects of spherical optical components can generate scattering light when an annular illumination beam irradiates on the surface, to implement the sub-aperture scanning and imaging that covers the entire spherical surface. Then, a series of procedures such as the global correction of sub-apertures, the 3D stitching, the 2D projection and the digital feature extraction are taken to inspect spherical surface defects. Finally, actual size and position information of defects are evaluated quantitatively with the defects calibration data. The present invention achieves the automatic quantitative evaluation for surface defects of spherical optical components, which considerably enhance the efficiency and precision of the inspection, avoiding the influence of subjectivity on the results. Eventually, reliable numerical basis for the use and process of spherical optical components is provided.

Surface defects evaluation system and method for spherical optical components

The present invention discloses a wavelength scanning interferometer and a method for an aspheric surface measurement. The wavelength scanning interferometer comprises a set of tunable lasers () used as a light source, a Twyman-Green interferometer used for generating interference fringes, a translation platform () used for scanning an optical path difference along an optical axis, an image card () used for converting interference data to a digital signal and transmitting the digital signal to a computer (), and a data card () used for synchronizing the actions of a CCD camera () and the translation platform (). Different from the traditional aspheric surface measurement method, the interferometer is capable of measuring a surface with a high aspheric surface degree or a wavefront, and without the need of a zero compensation mirror. In addition, the method does not need a complex and usually expensive multi-dimensional movement platform.

Wavelength scanning interferometer and method for aspheric surface measurement

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Zhejiang, China

Yongying Yang