Patent Document ID: 9826201
Application ID: 15221879
Patent Status: 1

Claim One:
1. A method for determining dimensional properties of a measurement object, comprising the steps of: providing an optical measuring machine comprising a workpiece table and a camera having an image sensor and an imaging optics, wherein the imaging optics exhibits aberrations and is configured to be focused on a plurality of different working positions relative to the workpiece table, providing first calibration values that are selected such that the aberrations are minimized for a defined working position from the plurality of different working positions, providing second calibration values that represent an image field curvature of the camera, positioning the measurement object on the workpiece table, defining a first region of interest on the measurement object, determining a first working distance of the camera to the first region of interest, focusing the imaging optics using the first working distance and the second calibration values such that the first region of interest is substantially brought into the defined working position, recording an image of the first region of interest while it substantially is in the defined working position, and determining measurement values that represent the dimensional properties of the measurement object in the first region of interest on the basis of the image and on the basis of the first calibration values, wherein the first calibration values further comprise distance-dependent correction values for correcting at least one of telecentricity errors and coma, and wherein the measurement values are determined in dependence on the first working distance and the distance-dependent correction values.