Speaker
Description
Multi-photon scanning microscopy is a well-established method in bio medical imaging. The shift of the excitation wavelength to longer wavelengths (NIR and beyond) allows for a deeper optical penetration into biological tissue. As each pixel must be probed individually the image acquisition time of conventional systems is inertia limited by the oscillation frequency of two galvanometric mirrors and can take seconds, making physiological processes that occur on a shorter timescale inaccessible for scanned imaging.
We characterize the prototype in development of the Spectro-Temporal Laser Imaging by Diffractive Excitation (SLIDE) system that aims to overcome this limitation. This multi-photon scanning microscope utilizes a fast tunable Fourier Domain Mode Locking (FDML) Laser with a center wavelength of 1064 nm and a pulse repetition rate up to 960 MHz in combination with a diffractive element to achieve frame rates of up to 4 kHz and live volume imaging of a 150 x 100 x 50 µm^3 volume sampled at a pixel density of 4 x 4 x 2 pixel/µm with a volume rate of 40 volumes per second.
At these scanning speeds, corresponding to a pixel dwell time of 1 ns, the fluorescence lifetimes of fluorophores that usually lie in the nano second range are a limiter to imaging speed. We therefore focus on the imaging of physiological structures like collagen or samples labelled by lithium niobate (LiNbO_3) nanoparticles that give an almost instantaneous response by second harmonic generation.
