大口径深焦比Hindle球面镜曲率半径精确测量

Precise measurement for radius of curvature of large-aperture fast Hindle sphere

Hindle法无像差法检测凸双曲面中,大口径深焦比球面反射镜的曲率半径测量是关键技术之一。提出了一种基于激光干涉仪、三坐标测量臂及标准定标球相结合测量球面曲率半径的方法。在球面镜面形干涉检验光路中引入一个标准定标球体,将其球心与检测系统的焦点重合,应用FARO测量臂对标准定标球体球心和被检球面镜镜面点坐标进行采样,从而计算球面镜曲率半径值。对一个口径Φ800 mm、设计半径为861.8 mm的球面标准反射镜进行曲率半径测量及精度分析,实测曲率半径为862.036 mm,系统的最大测量误差为±0.036 mm,测量不确定度为±0.015 mm;经Zemax软件分析,该测量误差对双曲面检测精度的影响仅为精度要求的3.4%,验证了这种球面半径测量方法的有效性及实用性。

The measurement of radius of curvature of the large spherical mirror is a key technique in Hindle test for convex hyperboloid. The measurement method for radius of the spherical mirror is proposed,which involves an interferometer,a three-coordinate measurement arm and a standard calibration sphere. The standard calibration sphere is inserted into the configuration of sphere figure error testing and is located at the focus of the testing system. The FARO edge is used to measure the coordinates of the center of the standard calibration sphere and the surface of the spherical mirror under test. And the radius of curvature of the tested spherical mirror can be calculated. The actual radius of a large sphere with the aperture Φ800 mm and the designed radius 861. 8 mm was measured in the method,and the measurement precision was analyzed. The actual radius of the sphere is 862. 036 mm,and the maximal measurement error is ± 0. 036 mm,and the measurement uncertainly is ± 0. 015 mm. With the analysis by Zemax,the influence of the measurement error is 3. 4% of the required precision. The availability and practicability of the measurement method are verified.