Electro-optic and Acousto-optic Laser Beam Scanners

Abstract

Optical solid state deflectors rely on the electro-optical or acousto-optic effect. These Electro-Optical Deflectors (EODs) and Acousto-Optical Deflectors (AODs) do not contain moving parts and therefore exhibit high deflection velocities and are free of drawbacks associated with mechanical scanners. A description of the principles of operation of EODs and AODs is presented. In addition, characteristics, properties and the (dis)advantages of EODs and AODs, when compared to mirror based mechanical deflectors, is discussed. Deflection angles, speed and accuracy are discussed in terms of resolvable spots and related quantities. Also, response time, damage threshold, efficiency and the type and magnitude of beam distortions is addressed. Optical deflectors are characterized by high angular deflection velocities, but small deflection angles. Whereas mechanical mechanical scanners are characterized by relatively small deflection velocities, but large deflection angles. Arranging an optical deflector and a mechanical scanner in series allows to take advantage of the best of both worlds.

High‐Speed Large‐Field Multifocal Illumination Fluorescence Microscopy

“…Modern AODs can achieve megahertz scanning speeds, thus allowing random access with high accuracy. Yet, their major drawback is the small deflection angles (typically <0.05 rad) and limited resolvable number of spots (typically <500) . Here, we capitalized instead on the large diffraction angle and the multi‐beams strategy introduced by the beam‐splitting grating.…”

Advances in Two-Photon Scanning and Scanless Microscopy Technologies for Functional Neural Circuit Imaging

“…AODs provide a small maximum deflection angle, Δθ scan , typically 0.01–0.05 rad compared to 0.5 – 1 rad for a galvanometer scanner [97]. This limits the image resolution to the AOD pointing accuracy if a large FOV is required [87].…”

High contrast imaging and flexible photomanipulation for quantitative in vivo multiphoton imaging with polygon scanning microscope

“…However, PMs face the limitations of a fixed scanning angle and cannot perform photomanipulation. High speed light modulators (acousto‐optics or electro‐optics ) could be used to selectively pattern the scanning intensity, but they accrue additional losses in optical energy, either through optical polarization, diffraction or increased optical aberrations . Alternative approaches such as random access scanning , temporal focusing methods and collinear aligning of a second photomanipulation beam offer greater flexibility, but they are also constrained by lower optical efficiency due to diffraction and chromatic aberrations leading to a reduction of axial resolution .…”