Detection device for internal defects of object with smooth surface

Abstract

The invention relates to the technical field of optical detection, and discloses a detection device for internal defects of an object with a smooth surface. The detection device comprises a laser, a beam expanding mirror, a speckle generating device, a shearing interference device and a charge coupled device image sensor; a laser light emitted from the laser is expanded by the beam expanding mirror and irradiates the speckle generating device, speckles are formed by the speckle generating device and enters a smooth surface of a to-be-measured object, and the speckles carrying surface information of the to-be-measured object irradiate a target surface of the charge coupled device image sensor via the shearing interference device to form a speckle interferogram on the target surface of the charge-coupled device image sensor, wherein, the speckle generating device comprises a plurality of frosted glass, and rough surfaces of the plurality of frosted glass face the beam expanding mirror. The detection device does not change surface properties of the to-be-measured object, and is high in laser utilization rate and low in requirements on the laser.

Description

technical field [0001] The invention relates to the technical field of optical detection, in particular to a detection device for internal defects of objects with smooth surfaces. Background technique [0002] Since speckle can only occur on the surface of rough objects, the method of Michelson shear speckle interferometry is mainly used for the measurement of rough surfaces. In the measurement of smooth surface objects, the occurrence of speckle is generally adopted by spraying the imaging agent to change the smooth surface into a rough surface where speckle can occur; Rough surfaces reflect to smooth surfaces. [0003] However, the method of spraying the imaging agent may lead to changes in the surface morphology of the measured object. Uneven spraying or too little spraying will result in the failure to detect defects in the end. In practical applications, spraying on a smooth surface may cause the measured object to The physical and chemical properties of the surface c...

AI Technical Summary

Problems solved by technology

[0003] However, the method of spraying the imaging agent may lead to changes in the surface morphology of the measured object. Uneven spraying or too little spraying will result in the failure to detect defects in the end. In practical applications, spraying on a smooth surface may cause the measured object to The physical and chemical properties of the surface change, making the measured object unusable, so in actual measurement, it is not applicable

However, if the laser is used to irradiate the rough surface and then reflect from the rough surface to the smooth surface of the measured object, since the rough surface forms diffuse reflection, the light beam reaching the smooth surface is very small, and the utilization rate of the laser is extremely low. Even if it is a high-power laser, it may Due to placement reasons, the speckle received on the smooth surface cannot be measured, or most of the light reflected on the smooth surface comes from the laser or surrounding objects, and there is less useful information

Images