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提出了一种对材料表面平度进行测量和评价的光学和数字相结合的新方法。建立了表面水平侧影在非相干光学成像系统中的数学模型，把侧影看成是放在空间不变线性系统中的阶跃函数，在非相干光学成像系统中其图像输出即是在空间频率意义下阶跃函数的傅立叶交换。设计了一套实现上述测量的光学数字系统。并用数字信号处理技术消除背景噪声，对表面的不平斑粒进行模式识别和统计分类。最后实测衍射强度的纹波，分析成像系统的冲激响应，计算该系统的光学传递函数，从而评价整个系统的成像质量和精度。
A new method combining optical and digital measurement and evaluation of material surface flatness is proposed. The mathematical model of surface-level silhouette in incoherent optical imaging system is established. The silhouette is regarded as a step function in the space-invariant linear system. In non-coherent optical imaging system, the image output is in the sense of spatial frequency Fourier Transform of Next Step Function. An optical digital system was designed to achieve the above measurements. And use digital signal processing technology to eliminate the background noise, the pattern of uneven surface speckle pattern recognition and statistical classification. Finally, the ripple of the diffraction intensity was measured, the impulse response of the imaging system was analyzed, and the optical transfer function of the system was calculated to evaluate the imaging quality and accuracy of the whole system.