Aberration-free 3D imaging via DMD-based two-photon microscopy and sensorless adaptive optics

In this Letter, we present a new, to our knowledge, aberration-free 3D imaging technique based on digital micromirror device (DMD)-based two-photon microscopy and sensorless adaptive optics (AO), where 3D random-access scanning and modal wavefront correction are realized using a single DMD chip at 22.7 kHz. Specifically, the DMD is simultaneously used as a deformable mirror to modulate a distorted wavefront and a fast scanner to maneuver the laser focus in a 3D space by designed binary holograms. As such, aberration-free 3D imaging is realized by superposing the wavefront correction and 3D scanning holograms. Compared with conventional AO devices and methods, the DMD system can apply optimal wavefront correction information to different imaging regions or even individual pixels without compromising the scanning speed and device resolution. In the experiments, we first focus the laser through a diffuser and apply sensorless AO to retrieve a corrected focus. After that, the DMD performs 3D scanning on a Drosophila brain labeled with green fluorescent protein. The two-photon imaging results, where optimal wavefront correction information is applied to 3×3 separate regions, demonstrate significantly improved resolution and image quality. The new DMD-based imaging solution presents a compact, low-cost, and effective solution for aberration-free two-photon deep tissue imaging, which may find important applications in the field of biophotonics.