Volumetric random-access multi-focus scanning based on fast light modulation

Highly efficient scanning of focused light in the three-dimensional space is of great significance in many fields, such as volumetric biomedical imaging, laser beam machining, and optical metrology. Here we propose light-modulation-based volumetric multi-focus scanning (LM-VMS) by generating a complex field superposed of multiple spherical wave components. Each spherical wave component corresponds to a focus, and can be modulated independently by changing its tilt term and defocus term. Therefore, the positions of all the foci can be manipulated in a random-access scan mode. We showed the excellent performance of LM-VMS in a scanning system based on a digital micromirror device. This system had a lateral scanning radius of 2.43 mm and a longitudinal scanning range of 140 mm. Its lateral resolution in the focal plane was 28.1 ± 0.4 μm. Furthermore, we demonstrated that LM-VMS could scan 24 foci simultaneously along independent, arbitrary trajectories at a rate of 22.7 kHz. LM-VMS is a promising solution for optical random-access scan to considerably accelerate the information acquisition and machining in various industrial applications.