Verification of the optical design by simultaneous measurement of centering errors and relative surface distances inside of optical systems

摘要

Especially for optical compound systems the precise geometric alignment of every single element according to the optical design is essential to obtain the desired imaging properties. In this contribution we present a technology for the measurement of the complete set of geometric alignment parameters in assembled systems. During the measurement the deviation of each center or curvature with respect to a reference axis is measured. These data are further processed in order to provide the shift and tilt of every single lens or group of lenses with respect to a defined reference axis. The centering errors of up to 40 surfaces within a system under test can be measured with accuracies in the range of an arc second. In addition, the relative distances of the optical surfaces (center thicknesses of lens elements, air spacing in between) are optically determined in the same measurement system by means of low-coherent interferometry. The measured results can be used for tolerance testing of the sample with respect to the given optical design. In addition, the obtained information can also be applied for the direct compensation of geometrical alignment errors of every single lens in the assembly for the optimized assembly of high-precision optics.