Millisecond photon-to-photon latency and high-speed volumetric projection system for optogenetics

Stimulating motile specimens via optogenetics requires high-speed light pattern modulation and projection to track target motion with millisecond-scale low latency. Although a millisecond-latency microscopic projection system has been reported, low-latency volumetric projection remains currently unachieved. Given that most biological specimens possess 3D cell distributions, such low-latency volumetric projection is essential. This paper proposes a high-speed volumetric projection method using a low-latency DMD, a high-speed TAG lens, a camera microscope, a vision system, and fiber illumination. The developed prototype system demonstrated a mean photon-to-photon latency of 6.66 ms and projected six volumetric patterns in 1,218 μs total.