Dynamic wavefront shaping with an acousto-optic lens for laser scanning microscopy

Abstract

Acousto-optic deflectors (AODs) arranged in series and driven with linearly chirped frequencies can rapidly focus and tilt optical wavefronts, enabling high-speed 3D random access microscopy. Non-linearly chirped acoustic drive frequencies can also be used to shape the optical wavefront allowing a range of higher-order aberrations to be generated. However, to date, wavefront shaping with AODs has been achieved by using single laser pulses for strobed illumination to 'freeze' the moving acoustic wavefront, limiting voxel acquisition rates. Here we show that dynamic wavefront shaping can be achieved by applying non-linear drive frequencies to a pair of AODs with counter-propagating acoustic waves, which comprise a cylindrical acousto-optic lens (AOL). Using a cylindrical AOL we demonstrate high-speed continuous axial line scanning and the first experimental AOL-based correction of a cylindrical lens aberration at 30 kHz, accurate to 1/35^th of a wave at 800 nm. Furthermore, we develop a model to show how spherical aberration, which is the major aberration in AOL-based remote-focusing systems, can be partially or fully corrected with AOLs consisting of four or six AODs, respectively.

Multifunctional Beam Manipulation at Telecommunication Wavelengths Enabled by an All‐Dielectric Metasurface Doublet

“…Accordingly, this device is anticipated to be usable in applications in optical metrology, laser scanning, spectroscopy, laser diodes, acousto‐optics, and optical processors. [ 55,56 ]…”

Technologies for imaging neural activity in large volumes

“…Even at tens of microns outside the natural z focus depth, defocus methods already suffer from degraded image quality and substantially reduced resolution and signal-to-noise ratio 70,75,80,81 (although in principle, AODs can be driven to shape the excitation wavefront in order to correct for aberrations 84,85 ). This can be problematic for experiments where diffraction-limited resolution is required (e.g., imaging synaptic terminals).…”

Remote focusing in confocal microscopy by means of a modified Alvarez lens

“…However, these systems possess a minimal response time of more than several milliseconds, which is inadequate for high‐speed recording. Only acousto‐optic lenses (Kaplan et al ., ; Mermillod‐Blondin et al ., ; Konstantinou et al ., ), whose phase front modulations are generated by ultrasonic waves, can achieve refocusing rates above 100 kHz. The main drawbacks of these lens types are that they can either be only operated in an oscillating mode (such as the tunable acoustic gradient index (TAG) lens) or have a fixed focusing speed which is determined by the velocity of the travelling acoustic wave (Konstantinou et al ., ).…”