Fluorescence microscopy is a common method to monitor the activity of neurons in the brain. Typically, such fluorescence images represent a two-dimensional section or focal plane in the brain. Yet, how can fluorescence microscopy be utilized to explore structures whose activity unfolds in multiple focal planes at the same time? To observe such processes at high time resolution, caesar scientists Andres Flores Valle and Johannes Seelig developed a new method.
Their trick: employing Bessel rays. Laser rays are modified so that they no longer focus on a single point, but along an axis. This allows these rays to illuminate several layers at once.
Four of these Bessel rays were used to illuminated a sample from different angles. An image reconstruction algorithm, comparable to methods known from CT scans, then turned the recorded images into three-dimensional objects. This method promises a new look at the dynamics of spatially extended systems with fast dynamics, such as groups of cells in the brain.
Flores Valle, A., Seelig, J.D. (2019). Two-photon Bessel beam tomography for fast volume imaging. Opt. Express 27, 12147-12162. DOI: https://doi.org/10.1364/OE.27.012147