The LenScan mirror positioner of Fogale, France, can determine the relative position of each optical surface in the optical system with high precision, such as the distance between the lenses, the thickness of the center of the lens, the optical path difference, etc., for optical assembly, especially the assembly of lens groups, suitable for objective lenses , The assembly and monitoring of aspherical compensators can also be used for the adjustment of astronomical long focal length mirrors, with an accuracy of micron level. Scope of application: component position along the optical axis, center thickness: lens, prism, plane mirror, CCDs; optical assembly: lens position, air gap, glue gap; single component control: thickness and refractive index; flat glass thickness test: float French glass, LCD panel. Application areas: for R&D: to determine the wrong position of the components in the assembly, measure the time gap to feed back to the optical design; for production: to monitor the distance between the components and the thickness of flat glass in real time during the assembly and adjustment process; for quality control: Verify the center thickness change of the lens before and after polishing, control the material of the lens, and control the assembly after production