Patent ID: 9400220
Filing Date: 2016-07-26
CPC Classification: G02B,G03F

Claim Text:
1. A method for detecting focus plane based on Hartmann wavefront detection principle, which is implemented by a system for detecting focus plane constituted of a light source and beam collimating and expanding unit, frontal set of lens, measured silicon wafer, posterior set of lens, microlens array and CCD detector, wherein the front set of lens and the posterior set of lens forms a 4f system, and the measured silicon wafer is on a cofocal plane of the 4f system, the method for detecting focus plane is characterized by that an emerging planar wavefront of the light source and the beam collimating and expanding unit passes through the frontal set of lens, is incident on a surface of the measured silicon wafer and reflected by the measured silicon wafer, passes through the posterior set of lens and the microlens array, and finally imaged in the CCD detector; if the measured silicon wafer is located on the cofocal plane of the frontal set of lens and the posterior set of lens, the microlens array enables imaging of the planar wavefront; and if the measured silicon wafer is defocused, the microlens array enables imaging of the spherical wavefront; and the measurement for detecting the focus plane of the measured silicon wafer is accomplished based on varied situations of the imaged light spot in the CCD detector.