提高线阵CCD测量光束中心位置精密度的方法

用线阵CCD测量类钟形分布的光束中心位置时，常用高斯分布模型和最小二乘（LSM）回归计算。提出一种用准高斯分布以提高测量灵敏度、用截取阈值较高的方式以减少噪声影响、用加权LSM回归以提高精密度的方法。由于高斯曲线拟合时的因变量不等权，选用加权回归和等权回归相比，ADC化整误差和光电测量误差的影响将减小一个数量级。根据CCD器件的参数，能够确定像元数据的误差限值。再用蒙特卡罗法模拟误差分布规律，通过截尾分布数值的加权回归，求出使测量精密度提高的合理光束宽度范围。已将此方法用于冲击电流计的改进设计和位移测量，使微电流测量的精密度提高达两个数量级，并使30mm内的微位移测量的非线性标准差不大于0．0025％。

Improvement of the Measurement Precision of Light Beam Center by Linear CCD

In order to measure the light beam center of bell curve distribution precisely by linear CCD,the common technique is to apply Gaussian distribution model and the least squares method(LSM).The quasi-symmetry truncation through setting the threshold voltage is applied to decrease the influence of noise,and the weighed LSM regression is adopted to increase the precision of measurement.Compared with the simple LSM,the weighed LSM will decrease the influences of ADC rounding error and photoelectric error at least one order of magnitude because the weight of dependent variables for Gaussian distribution regression is not equal.According to the CCD characteristic parameters,such as transmission efficiency,the CCD pixel error limits can be assured.The appropriate width range of light beam to optimize the precision will be calculated by numeric regression with Monte-Carlo error simulation.Application of the technique into the ballistic galvanometer AC4/3 and microdisplacement measurement,the precision of micro electric current can increase two orders of magnitude,and the nonlinear standard deviation for microdisplacement measurement is not more than 0.0025% of 30?mm.