Lens center surface air gaps and thickness measurement in catadioptric telescope corrector lens using non-contact in situ low-coherence interferometry

Due to the negative diopter lens constructions of conventional remote sensing catadioptric telescopes, the corrector lens produces divergent optical property, resulting in difficulties of measuring the center thickness of the lenses and the air gaps between lens interfaces. One solution to address this issue is to incorporate a positive diopter lens on the image side during the optimization of remote sensing catadioptric telescope lenses and thus the lens center thickness as well as interlens surface air gap distances can be measured accurately from the image side by low-coherence interferometry. In this study, the lens center thickness and inter-lens center surface air gap distances of an enclosed corrector lens was measured in a single scan by using non-contact in situ measurement method of low-coherence interferometry and resulted in a significant advancement in the assessment and verification process. It facilitated the determination of whether the corrector lens met the required specifications of remote-sensing instrument during the process of assembly, integration, and successive environmental testing.