Method and computer program product for oct measurement beam adjustment

A method for determining at least one of translational or rotational deviations between a measurement coordinate system of a measurement mirror scanner being tiltable about two axes and deflecting a measurement beam two-dimensionally, and a processing coordinate system of a processing mirror scanner being tiltable about two axes and deflecting both the measurement beam deflected by the measurement mirror scanner and a processing beam two-dimensionally onto a workpiece, the measurement beam reflected at the workpiece returning on a path of the incident measurement beam and being captured by a spatially resolving measurement sensor to ascertain spatially resolving information of the workpiece, and in a zero position of the measurement mirror scanner, the reflected measurement beam being imaged in a sensor image of the measurement sensor, onto a previously known image position, the method comprising at least one of:

• step a) ascertaining an x-y focal position deviation of the processing beam relative to a pinhole diaphragm center of a pinhole diaphragm detector disposed on a workpiece support plane by scanning the pinhole diaphragm with the processing beam deflected by the processing mirror scanner in an x-y grid and by evaluating a laser power detected at each of grid points, and by fixing the processing mirror scanner in a scan position having been corrected based on the ascertained x-y focal position deviation, the focal position of the processing beam in the scan position being situated in a predetermined position;
• capturing spatially resolving height information of the pinhole diaphragm, with the processing mirror scanner fixed in a corrected scan position, by using the measurement sensor to scan the pinhole diaphragm with the measurement beam deflected by the measurement mirror scanner;
• and
• determining a translational deviation between the processing and measurement coordinate systems based on a deviation, present in the sensor image of the measurement sensor, between the previously known image position corresponding to the focal position of the processing beam and the pinhole diaphragm center captured from the height information;
• or
• step b) deflecting the measurement beam by respective positive and negative fixed magnitudes in the workpiece support plane by tilting the processing mirror scanner about one, first tilt axis thereof and, with the processing mirror scanner fixed in the respective tilted scan positions, capturing a linear height edge disposed at the workpiece support plane by using the measurement sensor for a respective line scan of the measurement beam by deflecting the measurement mirror scanner about one, second tilt axis thereof, and ascertaining an axis of the processing coordinate system based on captured points of intersection of the two line scans with the height edge;
• deflecting the measurement beam by respective positive and negative fixed magnitudes in the workpiece support plane by tilting the measurement mirror scanner about the other, first tilt axis thereof and, with the measurement mirror scanner fixed in the respective tilted scan positions, capturing the height edge by using the measurement sensor for respective line scans of the measurement beam by deflecting the processing mirror scanner about the second tilt axis thereof, and ascertaining an axis of the measurement coordinate system based on the captured points of intersection of the two line scans with the height edge;
• and
• determining a rotational deviation between the processing and measurement coordinate systems based on the ascertained axes of the processing and measurement coordinate systems.