基于加权最小二乘法的干涉图校准方法

Method for calibrating interferogram based on weighted least square

针对现有干涉图校准方法的不足,提出了一种基于加权最小二乘法的干涉图校准方法。根据干涉图中标准件边缘与干涉条纹边缘之间的差异,用合适大小的掩模对标准件的边缘进行初步判定和提取,再利用加权最小二乘法对提取出的边缘进行精确定位。通过计算标准件中已知尺寸部分在干涉图中所占据的像素数目,求出每个像素代表的实际距离,完成校准。实验表明,该方法的计算耗时较霍夫变换法减少一半,定位精度小于1个像素,且适用于不同对比度的干涉图,具有很强的实用性。

A new method depending on weighed least square was proposed, aiming at the shortcomings of the existing interferogram calibration method. It used the edge information differences between standard part＇s edges and fringes＇ edges, then extracted the target edges by using appropriate mask, and finally used the weighed least square way to position the edge more exactly. The new method can figure out the real length of each pixel finally depending on the standard part＇s known size. The experiments show that this method costs half time than Hough transform, and the positioning accuracy is less than 1 pixel. It can calibrate each type of interferogram well with strong practicability.