Phase-shifting speckle interferometry with unresolved speckles: A theoretical investigation
Phase-shifting speckle interferometry with unresolved speckles: A theoretical investigation
复制标题
未解决散斑的相移散斑干涉测量：理论研究
DOI：
10.1016/0030-4018(96)00072-7
复制
发表时间：
1996
影响因子：
2.4
通讯作者：
M. Lehmann
中科院分区：
文献类型：
--
作者：
M. Lehmann
在相移散斑干涉测量中，散斑场强度的变化往往会导致某些像素点失效。要么是饱和，要么是低调制，导致无法计算出可靠的相位。从一个标准出发，当一个点没有饱和并且它的调制超过最小阈值时，它就被认为是有效的，测量的效率被定义为有效点的分数。为了计算该效率，对于散斑和平滑参考波设置，对于每个像素的任意数目n的散斑，推导出背景强度和调制的统计分布。确定了导致最大效率的最佳波场强度。这一结果与普遍接受的说法相矛盾，即满意的测量需要良好的散斑：最大效率预计会随着n的增加而降低，但事实证明，对于相对较高的n值，仍然令人满意。对于较低但合理的调制阈值，当一个像素在多个散斑上积分时，散斑参考波设置的效率甚至会得到提高。
In phase-shifting speckle interferometry, the varying intensity of speckle fields always causes some pixels to be invalid. It is either saturation or low modulation that prevents a reliable phase from being calculated. Proceeding from a criterion that considers a point to be valid as soon as it does not saturate and its modulation exceeds a minimum threshold, the efficiency of a measurement is defined as the fraction of valid points. In order to calculate this efficiency, the statistical distribution of the background intensity and the modulation is derived for an arbitrary number n of speckles per pixel, for both the speckle and the smooth reference wave setup. Optimum wavefield intensities leading to a maximum efficiency are determined. The results contradict the generally accepted statement that satisfying measurements require well resolved speckles: The maximum efficiency, which is expected to decrease as n increases, proves to remain satisfactory for relatively high values of n. For low yet reasonable modulation thresholds, the efficiency of the speckle reference wave setup is even improved when a pixel integrates over several speckles.