Yi Xue
Title: Three-dimensional multi-site random access photostimulation (3D-MAP)
Abstract: Optical control of neural ensemble activity has been crucial for understanding brain function and disease, yet no technology can achieve optogenetic control of very large numbers of neurons at extremely fast rates over a large volume. State-of-the-art multiphoton holographic optogenetics requires high power illumination that only address relatively small populations of neurons in parallel. Conversely, one-photon holographic techniques can stimulate more neurons but with a trade-off between resolution and addressable volume. We introduce a new one-photon light sculpting technique, termed Three-Dimensional Multi-site random Access Photostimulation (3D-MAP), that simultaneously overcomes all these limitations by dynamically modulating light in both the spatial and angular domain at multi-kHz rates. Electrophysiological measurements confirm that 3D-MAP achieves high spatial precision in vitro and in vivo. Using 3D-MAP, we then interrogate neural circuits with 3D multi-site illumination with high resolution over a large volume of intact brain that existing techniques cannot achieve.
Biography: Dr. Xue is a postdoctoral scholar in Prof. Laura Waller's group, Dept. of EECS, UC Berkeley. His research projects focus on the interdisciplinary field that draws from optics and neuroscience. His current project is to design optical microscopy along with computational techniques for optogenetics and fluorescence imaging. He completed my PhD and master’s degree in Mechanical Engineering at MIT, and my bachelor’s degree in Optical Engineering at Zhejiang University, China.
Yunshan Jiang
Title: Time stretch LiDAR
Abstract: The need for imaging and ranging in robotics and self-driving has brought LiDAR to the forefront of consumer technology. Among various approaches, time-of-flight ranging sets the benchmark for robust operation due to illumination with high-energy pulses and direct detection. Traditional methods based on mechanical scanning are inherently slow, bulky and prone to failure and are not well suited for the emerging applications. Conversely, spectrally scanning using tunable lasers is an inertia-free solution that offers fast scanning. In this presentation, we introduce Time-stretch LiDAR. Firstly proposed and implemented at UCLA, it is the first spectrum-scanned time-of-flight LiDAR and achieves ~MHz line scan rate with up to 256 pixels per line with a single laser and a single APD detector. The system allows foveated imaging for adaptive and efficient sampling of the target, an approach that is a potential solution to the big data problem in 3D imaging. We would also discuss how the detection range of the LiDAR can be extended with Optical Dynamic Range Compression.
Biography: Cathy Yunshan Jiang graduated from UCLA in 2019 with a Ph.D. degree in Electrical Engineering. During her Ph.D., she worked on analog optical computing, ultrafast optical imaging technologies, and ultrafast spectrum-scan LiDAR. She has published 6 research papers on journals including Nature Photonics, APL Photonics, and Optics Letters, as well as 10 conference publications including SPIE Photonics West, CLEO, and IEEE SUM. She is currently a Hardware Engineer at Waymo working on the next-generation LiDAR systems used at Waymo's self-driving cars.
Tong Ling
Title: High-speed interferometric imaging of fast nanometer-scale cellular dynamics
for all-optical non-invasive electrophysiology
Abstract: Functional imaging is a powerful tool for disease diagnosis, and it often relies on measuring macroscopic responses in the electric fields or hemodynamics. In this talk, I will introduce a new aspect of functional imaging at cellular resolution by tracking the fast nanometer-scale cellular dynamics using high-speed interferometric imaging techniques. I will describe the electromechanical coupling in the cell membrane and how it can lead to all-optical non-invasive electrophysiology. I will show how this new approach can be demonstrated in vitro using a common-path interferometric microscope to image propagating action potentials, and in vivo to map the early electrical responses of photoreceptors after the light stimulus via high-speed phase-resolved line-scan optical coherence tomography (OCT).
Biography: Tong Ling is a postdoctoral fellow in the Department of Ophthalmology and Hansen Experimental Physics Laboratory at Stanford University. He develops high-speed interferometric imaging techniques for a wide range of applications across multiple fields, including biomedical imaging in ophthalmology, high-precision metrology, and applied physics. He received his Ph.D. in 2016 and B.Eng. in 2011 from Zhejiang University, China. The randomly encoded hybrid grating he invented for versatile quadriwave lateral shearing interferometry was nominated for 2015 China’s Top 10 Optical Breakthroughs by the Chinese Journal of Lasers. He also received the Wang Daheng Optics Award for College Students by the Chinese Optical Society, the First Prize Scholarship by the China Instrument and Control Society, and the Outstanding Graduate Award by Zhejiang Province.