Design of a multi-modality DMD-based two-photon microscope system.

We present the modular design and characterization of a multi-modality video-rate two-photon excitation (TPE) microscope based on integrating a digital micromirror device (DMD), which functions as an ultrafast beam shaper and random-access scanner, with a pair of galvanometric scanners. The TPE microscope system realizes a suite of new imaging functionalities, including (1) multi-layer imaging with 3D programmable imaging planes, (2) DMD-based wavefront correction, and (3) multi-focus optical stimulation (up to 22.7 kHz) with simultaneous TPE imaging, all in real-time. We also report the detailed optomechanical design and software development that achieves high level system automation. To verify the performance of different microscope functions, we have devised and performed imaging experiments on Drosophila brain, mouse kidney and human stem cells. The results not only show improved imaging resolution and depths via the DMD-based adaptive optics, but also demonstrate fast multi-focus stimulation for the first time. With the new imaging capabilities, e.g., tools for optogenetics, the multi-modality TPE microscope may play a critical role in the applications pertinent to neuroscience and biophotonics.