Performance evaluation of galvanometric mirrors for fast scanning in multimodal laser microscopy

Abstract Galvanometric scanners (galvo-mirrors, GMs) are key beam-steering elements in laser scanning microscopy, where their dynamic performance directly limits imaging speed, precision and field fidelity. In practical microscopy systems, scanner behaviour is governed by dynamic parameters such as settling time, frequency response and phase delay, that critically influence image quality, particularly at high scanning rates. Here, we present a comparative characterization of two GM systems integrated into custom-built laser scanning microscopy platforms. Rather than evaluating standalone scanner units, both systems were examined as fully assembled components within operational microscopes, allowing combined effects of mirror inertia, driver electronics and feedback control to be assessed. Under identical driving conditions, scanner dynamics were quantified through measurements of step response, amplitude and waveform fidelity and frequency-dependent phase delay. These measurements were complimented by representative imaging examples that directly link scanner dynamics to observable image distortions. The results show that the first GM system exhibits faster step response, smaller phase delay and improved amplitude retention across the operational frequency range of 200–800 Hz, indicating higher dynamic bandwidth. In contrast, the second GM system demonstrates slower response and stronger amplitude attenuation at higher frequencies, leading to reduced usable field of view, geometric distortions and larger phase delay leading to misregistration between forward and backward scans. This study provides practical guidance for selecting and optimizing galvanometric scanners and scan parameters in high-performance laser scanning microscopy.