针对测量高功率激光驱动装置中大口径矩形反射光学元件的波前误差时测量角度和使用角度不完全相同引入的测量误差, 提出了将测量角度下的反射波前转换到使用角度的反射波前的换算及恢复方法。首先分析了将斜入射测量角度下的波前转换到使用角度下波前的余弦换算方法, 得到了实际测量角度与实际使用角度下的波前误差计算关系; 然后计算并分析了双三次插值算法本身引起的中频PSD1(功率谱密度)误差, 指出在满足有效口径测量的情况下, 选择的入射角度应该与实际使用的角度尽可能的相接近。最后, 基于410 mm×410 mm的熔石英反射镜开展了误差分析和实验验证。利用该方法将0°反射波前换算到45°反射波前, 并将得到的测试结果与45°直接测量得到的测试结果进行了比较。结果显示上述结果的PV值相差0.01λ, RMS值相差0.003λ, PSD1值相差0.08 nm; 表明该换算方法不仅能够准确计算出使用角度下反射波前的低频误差, 而且能获得相对准确的中频段PSD1误差。

The difference between the measurement angle and the use angle will produce measuring errors when the wavefront errors of the large reflective optics in a high power driving device are measured. So this paper proposes a method to convert the reflection wavefront in a measuring angle into the reflection wavefront in a use angle. Firstly, the cosine conversion method used in conversing the wavefront in an oblique incidence angle into the wavefront in the use angle was analyzed, and the calculation relationship of the wavefront errors between actual measurement angle and actual use angle was obtained. Then, the mid-frequency PSD1 (Power Spectral Density) error caused by the third interpolation algorithm itself was calculated, and it points out that the selected incident angle should be close to that the actual use angle as much as possible when the measuring condition meets the effective diameter measurement. Finally, the error analysis and experimental verification were carried out based on a 410 mm ×410 mm fused quartz reflector.Using this method, the 0° reflection wavefront was convered into the 45° reflection wavefront, and the measuring result after conversion was compared with that of the direction measuring result at 45°. The compared results show that the differences of PV values, RMS values and the PSD1 values are 0.01 λ, 0.003 λ and 0.08 nm, respectively. These results indicate that the method not only can calculate exactly the low frequency errors of reflection wavefront, but also can obtain the PSD1 mid-frequency error.