Defect detection system based on space step-by-step frequency shift illumination

Abstract

The invention discloses a defect detection system based on space step-by-step frequency shift illumination. The system comprises a light source, a microscope objective, a tube lens, an image detector,a control module and a data processing module, and the light source comprises a vertical illumination light source and an inclined illumination unit. Emergent light of the vertical illumination lightsource and the inclined illumination unit can irradiate an observed sample to excite a scattering field, and the scattering field is collected by the microscope objective, shaped by the tube lens, incident to the image detector and converted into a far-field intensity graph by the data processing module. The control module controls the lightening of each light source and the acquisition of an observed sample scattering field signal by the image detector under the illumination of each light source according to a time sequence. The data processing module reconstructs the spatial frequency spectrum information of the observed sample, and finally realizes detection imaging of complex defect feature contour information and detail feature information of the surface of the observed sample no matter under a transmission type illumination condition or a reflection type illumination condition.

Description

Technical field[0001]The invention relates to a product surface defect detection device and belongs to the field of surface defect detection.Background technique[0002]Defect detection on product surface is one of the important means to achieve product quality control, improve production technology, and optimize product performance. Manual inspection is the traditional method of product surface defect inspection, but with the development and progress of society, traditional inspection methods can no longer meet the requirements of inspection speed and inspection accuracy. With the development of industrial automation, with the advantages of non-contact, no damage, safety and reliability, wide spectral response range and high production efficiency, defect detection technology based on machine vision has developed rapidly. For example, the patent document with publication number CN105973912A discloses a leather surface defect detection device based on linear array light source illumina...

AI Technical Summary

Problems solved by technology

However, the methods proposed in relevant patent documents are all transmissive illumination, which is not suitable for microscopic observation of non-transparent sample surfaces

At the same time, when the LED lighting unit is far away from the center, the divergence angle of the incident light is large, and the accuracy of the sub-aperture spectrum information obtained by Fourier transform will be reduced.

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