Pilot capability evaluation of a modular laser diode-based prototype for beam focusing detection and calibration in laser processing

Abstract

Current methods for focus detection and calibration in laser processing face challenges such as limited accuracy, lack of automated self-calibration, compatibility issues with commercial machines, and high costs. This paper introduces a novel method and prototype based on laser diode technology, designed to efficiently detect and self-calibrate the focus state of processing lasers. The prototype utilizes a universal laser diode package as a detector, with the emitted light beam effectively locating the detection area. An integrated photodiode generates digital signal when identifying the beam characteristics of the detected processing laser, facilitating the development of an efficient closed-loop feedback control system. Experimental results demonstrate that when the detected laser beam spot size varies between 231 μm (minimum adjustable size) and 251 μm, the prototype accurately responds to these changes in real time, exhibiting a reliable linear correlation (R² > 0.999). Analysis of two types of detectors revealed similar high detection accuracy, with error rates of 0.023 % and 0.022 %, respectively. Furthermore, the prototype maintained a detection error rate ranging from 0.022 % to 0.049 % across detection distances of 100–250 mm, confirming consistent high accuracy under various conditions. The system also showcased self-calibration capabilities, adjusting the optical path to calibrate its focus state with an error rate of only 0.050 %. This cost-effective prototype, designed for high compatibility with existing processing machines, is expected to provide valuable insights into the field of laser processing.