Fast and light-efficient remote focusing for volumetric voltage imaging

Voltage imaging enables noninvasive recordings of electrical activity from excitable cells but volumetric imaging is constrained by the need for rapid refocusing. Existing remote focusing approaches are often too slow or light-inefficient. The authors introduce flipped image remote focusing (FLIRF), which replaces polarization optics with a miniature retroreflector to spatially separate incoming and refocused light, doubling light efficiency relative to beamsplitter-based designs and allowing volumetric voltage imaging at 500 volumes/s over a 150 μm axial range. Combined with light sheet imaging, FLIRF records activity from over 100 spontaneously active neurons in the zebrafish spinal cord in parallel.

Urs L. Böhm, Benjamin Judkewitz