Ultrafast laser scanning

Summary: We developed a scan multiplier unit (SMU) that can be combined with any mechanical scanner for general high-speed high-throughput laser scanning applications. The device makes use of a passive rescan strategy through a lenslet array to convert a single line scan from the scanner into multiple sequential line scans, leading to 1D scan patterns with scan rates and throughputs surpassing the physical inertia limit of the original scanner. The rescanned lines can also be configured to be non-overlapping, such that a single linear scanner sweep produces a raster scan over a 2D field of view (FOV) with a frame rate equal to the line-scan rate of the scanner. As an example, we apply this strategy to in-vivo calcium imaging in the mouse brain with two-photon microscopy, where we achieve an ultrafast line-scan rate up to 592 kHz, or frame rate of 16 kHz. We also combine a SMU with a second standard galvanometric scanner to achieve 2D imaging at 1 kHz rate over a 200 micron field of view, allowing us to perform 2PM imaging with an order of magnitude higher imaging throughput than previously achievable and penetration depths exceeding 500 µm.

• S. Xiao, J. T. Giblin, D. A. Boas, J. Mertz, “High-throughput deep tissue two-photon microscopy at kilohertz frame rates”, Optica 10, 763-769 (2023). link
• S. Xiao, I. Davison, J. Mertz, “Scan multiplier unit for ultrafast laser scanning beyond the inertia limit”, Optica 8, 1403-1404 (2021). link