基于多光谱技术的光学元件表面疵病检测

Optical Element Surface Defect Measurement Based on Multispectral Technique

为实现对光学元件表面疵病的精确测量和计数,提出了一种基于多光谱技术的光学元件表面疵病检测方法,该方法采用不同波长的入射光源均匀照明光学元件表面,通过暗场显微成像系统获得不同波长下的表面疵病图像。基于该方法研制了多光谱光学元件表面疵病检测系统,获得了365,405,436,486,550nm单波长光以及白光照明条件下光学样品表面疵病和标准样品图形的检测实验结果。实验结果表明,相比传统的白光照明检测技术,多光谱检测技术根据不同的材料性质选用不同波长的光作为入射光源,可以明显提高系统对光学元件表面疵病的检测能力,不仅可以提高测量精度,而且可以获取白光照明下无法检测到的疵病信息。

In order to measure optical element surface defects accurately, a method of optical element surface defect measurement based on the multispectral technique is presented. Incident light sources with different wavelengths are used to illuminate optical element surface uniformly, and defects images are captured by a dark field microscopic imaging system for every wavelength. The multispectral optical element surface defect measurement system is developed. The experiments to detect optical element surface defects and standard test samples are performed under illumination of light with different wavelengths （365, 405, 436, 486, and 550 nm） and white light. The experimental results show that compared with the traditional measurement technology with white light, significant improvement on the measurement performance of optical element surface defects is observed by using the multispectral measurement technique where the wavelength of incident light can be selected according to the material characteristic of tested object. Furthermore, the defect rneasurement accuracy is improved and many defects which cannot be detected with the traditional method are also obtained.