1Center for Optics, Photonics and Lasers (COPL), Faculty of Science and Engineering, Department of Physics, Engineering Physics and Optics, Université Laval, Québec, QC G1V 0A6, Canada
2Centre de Recherche du CHU de Québec-Université Laval, CHUL-Neurosciences, Québec, QC G1V 4G2, Canada
3Department of Psychiatry and Neurosciences, Faculty of Medicine, Université Laval, Québec, QC G1V 0A6, Canada
Miniature single-photon microscopes have been widely used to image neuronal assemblies in the brain of freely moving animals over the last decade. However, these systems have important limitations for imaging in-depth fine neuronal structures. We present a subcellular imaging single-photon device that uses an electrically tunable liquid crystal lens to enable a motion-free depth scan in the search of such structures. Our miniaturized microscope is compact () and lightweight (), with a fast acquisition rate (30–50 frames per second), high magnification (), and high resolution (1.4 μm) that allow imaging of calcium activity of fine neuronal processes in deep brain regions during a wide range of behavioral tasks of freely moving mice.