In order to investigate the response law of different interferometers to the mid-spatial frequency errors and obtain the relatively true power spectral density (PSD) distribution, the 4D AccuFiz, ZYGO DynaFiz and ZYGO GPI interferometers are respectively used to measure the periodic ripples and scratch samples, and the comparative analysis of the measured one-dimension PSD curves is made. The results show that the responsivities to the mid- and high-spatial frequency information are different for different interferometers, and the higher the interferometer resolution is, the higher the responsivity is. The instrument transfer function (ITF) curve is used to correct the measured PSD, and the truer PSD distribution is obtained. However, in the range of some frequency bands, there still exist some difference between the ITF curve and the practical response.

In order to investigate the response law of different interferometers to the mid-spatial frequency errors and obtain the relatively true power spectral density (PSD) distribution, the 4D AccuFiz, ZYGO DynaFiz and ZYGO GPI interferometers are respectively used to measure the periodic ripples and scratch samples, and the comparative analysis of the measured one-dimension PSD curves is made. The results show that the responsivities to the mid- and high-spatial frequency information are different for different interferometers, and the higher the interferometer resolution is, the higher the responsivity is. The instrument transfer function (ITF) curve is used to correct the measured PSD, and the truer PSD distribution is obtained. However, in the range of some frequency bands, there still exist some difference between the ITF curve and the practical response.

对镀制强激光薄膜的光学元件在外界环境中时,表面面形发生的变化进行了研究。理论分析了表面面形的变化机制,明确水致应力具有物理和化学两种形成机制,是改变镀膜元件面形的主要因素;实验研究了镀制激光高反膜的K9材料元件存放过程中面形变化趋势,发现这种趋势变化具有时间效应和湿度效应。

An algorithm based on singular value decomposition (SVD) is presented to fit the wavefront with Zernike polynomials. In the current algorithm, SVD is applied to decompose the matrix of the linear equations directly. In the process of computing the inverse matrix, a threshold value is employed to modify the reciprocals of singular values which are zero or too small. Then the Zernike coefficients can be worked out immediately. Compared with the typical Gram-Schmidt orthogonalization, SVD has good stabilization when solving the least square problem of the ill-conditioned equations or singular matrix. And also because of avoiding construction of normal equation group, the computational error is eliminated. Moreover, it is quite easy to be programmed.

As the resolution of the interferometer is rapidly. increasing, the higher requirement is proposed fo the interferometry. For avoiding losing of the useful information of the actual interferogram, an algorithm is presented based on singular value decomposition (SVD). which is more stable than other algorithms to some extent. The weight . coefficients of the orthogonal polynomials can be worked out directly, which can eliminate.the}computational error. Then an evaluation criterion is developed to choose the optimum Zernike polynomial number. The computer simulations of this algorithm are also made. The simulation experiments have proved that it is an efficient algorithm and can reconstruct the wavefront accurately ami stably.

提出了基于奇异值分解、采用泽尼克多项式拟合干涉波前的算法,该算法直接从线性方程组入手,对矩阵进行奇异值分解分解,在求解逆矩阵的过程中,采用阈值法对奇异值的倒数进行非常规的置换(∞→0),可直接得到系数向量。理论分析和实验证明,相对于传统的格拉姆施密特正交法,该算法可首先通过求解条件数判断线性方程矩阵是否奇异,对于解决病态方程组或奇异矩阵的最小二乘问题,有很好的稳定性,避免了由最小二乘构造的法方程组出现病态而引入的计算误差,且易于编程。

The system for effective area measurement of laser spot on target plane was designed based on the definition of effective area. A 12-bit CCD camera is used for the effecive area measurement. A bmp image of the beam profile is stored. This image is processing by software to evaluate the ratio of total energy and peak fluence (effective area). Some test results were given using effective area measurement system. The system was employed in the laser induced damage threshold test and it is helpful to improving the precision of laser induced damage threshold test.

从激光光斑有效面积的定义出发,采用CCD图像摄取技术,设计了一套激光光斑有效面积测量装置.在4种不同激光光斑能量分布和不同能量密度的情况下,用有效面积测量仪分别进行了实际测试验证.结果表明,该测量装置可以对任何能量非均匀分布的激光光斑的有效面积进行准确测试,有助于提高光学元件激光损伤阈值的测量精度.