基于多曝光图像融合的大动态范围散射信号获取

Large Dynamic Range Scatter Signal Acquisition Based on Multi-exposure Image Fusion

针对光散射法中散射信号的动态范围小影响光学元件表面粗糙度测量精度的问题,提出将图像融合技术应用到大动态范围散射信号的获取中。首先,采集光学元件同一位置处不同曝光时间的散射图像;然后,对其进行小波变换,分解后的低频分量采用散射信号最强原则、高频分量采用区域特性测量原则进行融合,经小波逆变换完成多曝光散射图像的融合;最后,将获取的大动态范围散射信号进行处理得到元件的表面粗糙度值。结果表明:融合后的散射信号与未经融合的散射信号相比,动态范围增加了3个数量级;融合后的散射信号计算得到的光学元件表面粗糙度值与白光干涉仪的测量结果一致,证明了该融合方法可用于大动态范围散射信号获取和光学元件的表面粗糙度测量。

In the light scattering method,the small dynamic range of the scattering signal will directly affect the measurement accuracy of optical element surface roughness.To solve the problem,the image fusion is applied to acquire large dynamic range scattering signal.First,the scattering images of different exposure times at the same position are collected.Then,it is transformed with wavelet transform,the decomposed low-frequency components are fused using the principle of strongest scattering signal,meanwhile highfrequency components are fused using the principle of regional characteristic measurement.The multiexposure scattering image fusion is completed by inverse wavelet transform.Finally,the large dynamic range scattering signal is processed to obtain the surface roughness value of the component.The results show that the dynamic range of the fused scattering signal is increased by 3 orders of magnitude compared with the unfused scattering signal.The surface roughness of optical elements calculated from the fused scattering signal is consistent with the measurement result of the white light interferometry,which proves the proposed fusion method can be used for large dynamic range scatter signal acquisition and surface roughness measurement of optical components.