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为提高哈特曼-夏克波前传感器(HS-WFS)的光斑质心探测精度以实现光学系统的高精度波前检测,提出了一种有效的质心探测方法。该方法利用非线性滤波和窗口法对整幅光斑图像进行全局处理后,结合中值滤波、三次样条插值和自适应Otsu阈值法对单个光斑进行局部处理。分析了三次样条灰度插值点个数不同,探测精度和计算时间的变化规律。采用该方法探测了含有噪声的光斑图像,其质心探测误差仅为0.0442pixel,比传统的非线性滤波、Otsu阈值法和探测窗口法探测精度分别提高了91.86%、87.97%和31.79%。对已知波像差的光学系统进行了仿真检测,得到的波前检测精度峰谷(P-V)值为0.0098λ,精度均方根(RMS)值达到0.0027λ。结果表明该方法能够提高质心探测精度,可用于高精度光学系统的检测。
In order to improve the detection accuracy of HS-WFS spot centroid to realize high-precision wavefront detection of optical system, an effective centroid detection method is proposed. This method uses the non-linear filtering and the window method to process the whole spot image globally, then combines the median filter, the cubic spline interpolation and the adaptive Otsu threshold method to process the single spot locally. The variation regularity of the spline interpolation points, the detection accuracy and the calculation time are analyzed. Compared with traditional nonlinear filtering, Otsu threshold method and detection accuracy of the detection window method, the detection accuracy of the spot with noise is only 0.0442pixel, which is 91.86%, 87.97% and 31.79% respectively. The optical system with known wave aberration was simulated and tested, the wavefront detection accuracy peak-to-valley (P-V) value was 0.0098λ and the precision root mean square (RMS) value was 0.0027λ. The results show that this method can improve the accuracy of centroid detection and can be used for the detection of high-precision optical system.