Waveness Profilometer of Large Optical Parts Insensitive to the Waveness and Roughness of Reference Mirror

研制了一种大型超光滑表面轮廓仪，该仪器在约0.4 gal均方根振动环境下的高度灵敏度为0.1 nm。在拍摄剖面时，以恒定速率扫描表面上的测量点。干涉测量系统继续测量目标点与其周围环境之间的高度差。在测量过程中使用参考镜中的相同部件，则反射镜的粗糙度不会影响测量数据。差分高度对高空间频率分量具有衰减强度。然而，数字信号处理可以恢复除了一个特征参数，曲面曲率半径的组件的原始强度。这个半径可以从仪器测量的另一个具有已知绝对轮廓的大型光滑表面的数据中计算出来。

A profiling instrument is developed for large supersmooth surfaces, which has a height sensitivity of 0.1 nm under vibrational environments of approximately 0.4-gal root mean square. In taking a profile, a measurement point is scanned on a surface at a constant rate. An interferometric system continues to measure a differential height between the aimed point and its surroundings. The same part in a reference mirror is used during the measurement, then the roughness of the mirror does not affect the measured data. The differential height has the attenuated intensities for high spatial-frequency components. However, a digital signal processing can retrieve the original intensities of the components except one characteristic parameter, the radius of curvature of the surface. This radius can be evaluated from the data which have been measured by this instrument for another large smooth surface having a known absolute profile.