A Practical Comparison of Beam Shuttering Technologies for Pulsed Laser Micromachining Applications

In this report we investigate the performance of various beam shutter technologies when applied to femtosecond laser micromachining. Three different shutter options are considered: a mechanical blade shutter, a bistable rotary solenoid shutter, and an electro-optic modulator (EOM) shutter. We analyzed the behavior of each shutter type during repeated open/close commands (period of 10 ≤ T ≤ 200 ms) using both high-speed videography and practical micromachining experiments. To quantify the performance at varying cycle periods, we introduce a new variable called the compliance that characterizes the average state of the shutter with respect to its intended position. We found that the solenoid shutter responds poorly to sequential commands. The mechanical shutter provides reliable performance for cycled commands as short as T = 40 ms, but begins to lag significantly behind the control signal for T ≤ 20 ms. The EOM shutter provides the most precise and reliable performance, with an opening time of only 0.6 ms and a high compliance with the signal commands, even when cycled very quickly (T = 10 ms). Overall, this study acts as an extensive practical guide for other laser users when considering different shutter options for their laser system and desired application.