Digital holographic detection device for subsurface defect of optical element

Abstract

The invention relates to a digital holographic detection device for a subsurface defect of an optical element. A light beam in the device is divided into a measuring light beam and a reference light beam, so that a measuring light path is obliquely incident to an object to be measured and symmetrically receives reflected light, the reflected light interferes with reference light, scattered light information of the subsurface defect is acquired from an interference pattern, the direct reflected light on the surface and stray light in a system are inhibited, and the scattered light information of the subsurface defect of the optical element is acquired. The detection device has the characteristics that: (1) a light source is a short coherent light source, so that the stray light in the system can be inhibited; (2) the measuring light path in the device is obliquely incident and symmetrically receives the reflected light, so that the direct reflected light on the surface of the optical element can be inhibited, only scattered light from the subsurface defect is received, and the signal-to-noise ratio of a signal is improved; (3) an optical fiber probe in the device is used for receiving the scattered light information, so that the limitation that a high-rate microscope objective is used for receiving the subsurface defect is overcome; and (4) the acquired image is analyzed and processed according to a digital holographic calculation principle, so that the quantitative depth information of the subsurface defect is acquired.

Description

technical field [0001] The invention relates to a digital holographic detection device for optical element subsurface defects. The invention uses a short coherent light source to obtain the scattered light information of the subsurface defect of the optical element through oblique incidence and symmetrical reception, and interferes with the reference beam; then uses the principle of digital holography to calculate and analyze the morphology and depth distribution of the subsurface defect quantitative information. The device of the invention is mainly used to realize the detection of subsurface defects of smooth optical elements. Background technique [0002] Subsurface defects of optical components are tree-like complex structures located in submicron to micron depths below the surface of the component. They are mainly divided into scratches, cracks and impurities, etc., and the extension depth can reach tens of microns to hundreds of microns. High-precision and efficient ...

AI Technical Summary

Problems solved by technology

The current detection methods include: (1) The detection method based on the combination of acid etching and confocal microscopy technology, although it is easy to observe the existence of defects, but due to the inhomogeneity of acid etching rate and surface roughness, it can only be used for isotropic Homogeneous materials have poor applicability, and the acid etching process will bring unpredictable damage to the components; (2) The method based on the combination of quantum fluorescence and confocal microscopy detection technology has high precision, but it needs to be combined with component grinding, The polishing process is integrated, the structure is complex, and the detection efficiency is low; (3) the polarized light non-destructive testing method, which judges subsurface micro-cracks through internal stress, is fast, but the beam needs to be injected from the side of the workpiece, so the practicability is limited, and the defect shape cannot be realized at present. (4) The internal reflection method is currently only suitable for the detection of thinner workpieces, and it is difficult to obtain defect quantitative information

Images