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 ( 10    mm × 17    mm × 12    mm ) and lightweight ( ≈ 1.4    g ), with a fast acquisition rate (30–50 frames per second), high magnification ( 8.7 × ), 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.

We present a module that can generate periodic light patterns and change their spacing, orientation, and position. It is done by using liquid crystal cells without pixelation (in contrast to spatial light modulators). The absence of mechanical movements allows this module to be integrated in miniature (wearable) microscopic systems to improve the image resolution by using the structured illumination method.

Miniature 1-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 indepth fine neuronal structures. We present a novel subcellular imaging 1-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 (10 mm x 17 mm x 12 mm), lightweight (≈ 1.4 g), provides fast acquisition rate (30-50 frames/second), high magnification (8.7x) 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 behavioural tasks of freely moving mice.