一种四波长轮换的表面形貌干涉测量系统

Four-wavelength switching interference measurement system for surface topography

针对相移干涉法测量表面三维形貌时深度测量范围受波长限制这一问题,提出一种四波长表面形貌干涉测量系统。通过滤波片的轮换,将白光LED光源的光切换出4个不同波长的光源,并依次进行单波长干涉。为解决多波长干涉图像数据处理,采用基于椭圆拟合的算法,在逐帧逐点的相位计算条件下,运用大小尺度相结合的算法实现高精度宽范围的表面形貌测量。实验结果表明:在深度测量范围扩大到约41倍的条件下,测量经中国计量科学研究院采用粗糙度国家基准校准的方波多刻线样板,得到的表面粗糙度数据与校准数据相比,相对误差为4.09%。说明在一定的深度范围内,该系统能够实现表面形貌的高精度测量。

Phase-shifting interferometry is an important measurement method for surface topography,but the depth measuring range is limited by the wavelength.A four-wavelength interference measurement system for surface topography was proposed.Through rotating the filters,4light sources with different wavelengths were switched out from LED light,and the single wavelength interference was conducted in turn.A data processing method for multiple wavelength interference images was put forward,which used the algorithm of elliptic fitting and the combination of varied scales to achieve wide-range high-precision surface topography measurement on the condition of calculating the phase point-by-point and frame-by-frame.Experimental results show that under the measurement depth expanded to nearly 41 times,the relative measurement error of surface roughness of square wave specimen with multiple grooves is only4.09%,compared to the data calibrated by China Institute of Metrology.Therefore,the system can realize high-precision measurement for surface topography in a certain range.