Lens refractive index and thickness measuring method and device based on differential confocal technology

The invention relates to a lens refractive index and thickness measuring method and a device based on the differential confocal technology, which belong to the technical field of optical precise measurement. The invention is used for the high-precision measurement of the refractive index and the thickness of a spherical lens. The invention is based on a ray tracing principle, utilizes an absolute zero point of a laser differential confocal responding curve for accurately determining the intersection point of the front surface of the lens to be measured and an optical axis, the intersection point of the back surface of the lens to be measured and the optical axis, and the position of a measuring lens with or without the lens to be measured, then, the position of the measuring lens and the curvature radius, the focal length and the pupil of the measuring lens which are measured in advance are utilized for carrying out facet ray tracing calculation on two spherical surfaces of the lens to be measured and the ref