Optical axis and thickness measurement method and device of differential confocal internal-focusing lens

The invention belongs to the technical field of optical precision measurement and relates to an optical axis and thickness measurement method and a device of a differential confocal internal-focusing lens. By means of an internal-focusing objective lens, the method utilizes an auto-collimation method to adjust the optical axis of the lens precisely; utilizes the characteristic that when a differential confocal response curve passes the absolute zero point, the vertex of a differential confocal light cone and the surface vertex of the lens to be measured can coincide to achieve the precise positioning of the surface vertex of the lens and to obtain a numerical aperture angle of emergent lights in two-time positioning of the vertex of the differential confocal light cone; and utilizes a ray tracing formula to calculate the central thickness of the lens. Meanwhile, an annular pupil is introduced during the light path measurement, the influence of aberration on a measurement result is reduced. By combining differ