Nature Meth. 12, 759–762 (2015)

Imaging techniques with high spatiotemporal resolution aid understanding of complex biological systems. Now, by integrating an optical phase-locked ultrasound lens into a laser-scanning two-photon fluorescence microscope, Lingjie Kong and colleagues from the USA have demonstrated volumetric imaging at tens of hertz. They basically insert an ultrasound lens between the pulse compressor and the scanning microscope. Precisely driving the lens using a phase-locked loop near its ∼455 kHz resonance provides a single axial scan in ∼1.1 μs, and integrating the lens into a two-photon microscope with galvo scanners achieves a ∼1 kHz cross-sectional frame rate. Depending on the axial scan ranges, 40 μm and 130 μm, the team has achieved lateral and axial resolutions of ∼0.5–0.6 μm and 2.9–4.6 μm, and 0.7–1.0 μm and 7.8–15.3 μm, respectively. The system was successfully applied to multicolour imaging of different processes that are sensitive to motion artefacts, including calcium and cell dynamics, and leukocytes in blood flow. The researchers say that the system can be used to upgrade existing laser scanning microscopes and will be attractive for improved three-dimensional biological imaging.