Multifocal structured illumination optoacoustic microscopy

Optoacoustic (OA) imaging has the capacity to effectively bridge the gap between macroscopic and microscopic realms in biological imaging. High-resolution OA microscopy has so far been performed via point-by-point scanning with a focused laser beam, thus greatly restricting the achievable imaging speed and/or field of view. Herein we introduce multifocal structured illumination OA microscopy (MSIOAM) that attains real-time 3D imaging speeds. For this purpose, the excitation laser beam is shaped to a grid of focused spots at the tissue surface by means of a beamsplitting diffraction grating and a condenser and is then scanned with an acousto-optic deflector operating at kHz rates. In both phantom and in vivo mouse experiments, a 10 mm wide volumetric field of view was imaged with 15 Hz frame rate at 28 μm spatial resolution. The proposed method is expected to greatly aid in biological investigations of dynamic functional, kinetic, and metabolic processes across multiple scales. Optoacoustics: Real-time microscopic imaging gets onto the grid Microvascular structures inside living tissues can now be imaged at rates suitable for video playback. Daniel Razansky from the University and ETH Zurich in Switzerland and colleagues have improved the speed of optoacoustic microscopes that use laser-generated ultrasonic waves to visualize subcutaneous tissue. Creating clear 3D microscopic images from optoacoustic data normally requires sequential focusing onto different points on a sample. The Swiss-based team reports that splitting the laser beam into a grid of multiple focused spots enables parallel data collection. The grid, produced with a diffraction grating and a two-lens condenser, can operate at multiple spatial scales. Calibration experiments and trials with live mice revealed the new microscope could offer a large centimetre-scale field of view at high speeds while simultaneously capturing microscopic details.