Enhancing laser scanner accuracy by grid correction

摘要

Lasers are used in micro manufacturing and microwelding applications. Manufacturing in micrometer scale features requires good laser beam properties, but also the axes of the laser machining system have to be accurate. One of the possible technologies is a scanner. Scanners are equipped often with galvanometric actuators, which enable accurate beam movement by changing the beam angle with mirrors and focusing the beam with a scanner lens. Both actuators and lens cause inaccuracy in the system. The optical shape of the lens is not ideal due to structure of the lens and lens grinding. Actuator performance is not ideal. One of the biggest reasons for scan angle error is drift, caused, for instance, by temperature changes. Because of these facts, laser scanner systems have to be calibrated regularly when at least some degree of accuracy is needed.rnIn this paper is presented a solution to compensate the entire working field of the scanner accurately, and calibrate the scanner field to match the actual working field. In the calibration process, distortions are first compensated with parameter changes and after that more accurately by marking a point matrix, measuring the locations of points and generating a new correction file. According to experimental results good accuracy can be achieved using the method.