Method for measuring surface defects based on spectral confocal sensor

Abstract

The invention discloses a method for measuring surface defects based on a spectral confocal sensor. A plane reflector is installed on an angular displacement table, the distance between a spectral sensor and a to-be-measured workpiece is adjusted, the acquisition of spectral peak intensity data at a set inclination angle is finished, the angular displacement table is adjusted to be at different inclination angles, until the acquisition of the spectral peak intensity data at all specified inclination angles is finished; a "steepness-distance-spectral peak intensity" characteristic curve is established; scanning measurement is performed on the to-be-measured workpiece, spectral peak intensity data of return light on the surface of the workpiece is acquired, and a reflectivity matrix of the surface of the to-be-measured workpiece is calculated; and a reflectivity threshold value is set, and a reflectivity sudden change region is identified by setting a reflectivity threshold value region,so that a defect region and a normal region are distinguished, and defect positioning and contour extraction are completed. A mathematical model between the spectral peak intensity and the surface reflectivity is built by an experiment method, and the surface defects are positioned by the reflectivity, so that a novel method is provided for the detection of the surface defects of optical elements.

Description

technical field [0001] The invention relates to the field of surface defect measurement, in particular to a surface defect measurement method based on a spectral confocal sensor. Background technique [0002] Ultra-precision optical components are widely used in civilian and military defense fields. Typical applications in the civilian field include lithography exposure mirrors, camera zoom lenses, optical instrument lenses, medical endoscopes and progressive mirrors, etc.; military and defense applications include astronomical telescopes such as the Hubble Telescope, laser weapons , infrared thermal imager, laser nuclear fusion, etc. The processing of ultra-precision optical components is inseparable from precision measurement technology. At this stage, the processing of ultra-precision optical components not only requires higher-precision surface measurement technology, but also requires the detection of surface defects. Surface defects have become an important indicator...

AI Technical Summary

Problems solved by technology

Using an interferometer equipped with a 1024×1024 pixel CCD to detect optical components with a caliber of 1m, its lateral resolution can only reach about 1mm, and it is difficult to detect submillimeter-level defects

[0007] 3) Although some defects are large in scale, it is difficult to distinguish them by traditional image processing methods, and the workload of manual detection is heavy, and it is prone to false detection and missed detection

High-end large optical components are difficult to handle, and there is a risk of additional defects or damage during the handling process

In addition, the handling process will also cause secondary clamping errors, which is unfavorable to the processing process

The visual method relies on manual screening with a magnifying glass or a microscope, which is inefficient and has the risk of missed and false detections

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