Low-cost camera based laser power monitoring and stabilizing for micro-hole drilling

摘要

In this study, a laser power monitoring and stabilizing system for micro-hole drilling based on optical outputs of a CMOS sensor is presented. The correlation between the laser power and the average brightness of the beam spots on the images was investigated. The estimated laser power was used to build an on-line closed loop control of micro-hole drilling. Experimental results showed that the shortest response time of the laser monitoring system was only 30 ms, which was much faster than a thermopile power meter. The average measuring error was 3%, compared with thermopile power meter. In the PCB drilling experiments of 30 kHz pulse repetition frequency, the PID controller could compensate the power disturbances from 38.4% to 1.8%, and the aspect ratio from 20% to 5%. This study demonstrates the feasibility to develop a low-cost laser power monitoring and stabilizing system in laser micromachining processes.