Conjugate adaptive optics in widefield microscopy with an extended-source wavefront sensor

Abstract

Adaptive optics is a strategy to compensate for sample-induced aberrations in microscopy applications. Generally, it requires the presence of "guide stars" in the sample to serve as localized reference targets. We describe an implementation of conjugate adaptive optics that is amenable to widefield (i.e. non-scanning) microscopy, and can provide aberration corrections over potentially large fields of view without the use of guide stars. A unique feature of our implementation is that it is based on wavefront sensing with a single-shot partitioned-aperture sensor that provides large dynamic range compatible with extended samples. Combined information provided by this sensor and the imaging camera enable robust image de-blurring based on a rapid estimation of sample and aberrations obtained by closed-loop feedback. We present the theoretical principle of our technique and proof of concept experimental demonstrations. ...

Widefield fluorescence microscopy with sensor-based conjugate adaptive optics using oblique back illumination

“…This was performed in a closed-loop feedback implementation similar to the one described in Ref. 13 where the control voltages applied to the DM at each feedback iteration are given by E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 7 ; 3 2 6 ; 5 2 3…”

“…More recently, this same principle of conjugate AO has made its way to the microscopy community. Reports in both simulation [6][7][8] and experiment [9][10][11][12][13] have demonstrated the FOV advantage of conjugate AO as well as its feasibility. For example, conjugate AO has been applied in scanning microscopy configurations using both one- 9 and twophoton 10,11 microscopy.…”

“…The crux of our previous transillumination conjugate AO implementation 13 was an extended-source wavefront sensor based on the use of a camera and a partitioned detection aperture, called a partitioned-aperture wavefront (PAW) sensor. This was originally developed to perform quantitative phase imaging either in a transmission 14 or reflection 15 geometry, and shares the same property of a Shack-Hartmann (SH) wavefront sensor that it provides a measure of local flux-density tilts in a light beam that is partially coherent.…”

“…It has also been applied in widefield (i.e., nonscanning) microscopy configurations with transillumination geometries. 12,13 The last of these involved the use of an extended-source wavefront sensor where the transillumination itself served to determine the wavefront aberrations, obviating the need for a "guide star" within the sample. While in principle this same wavefront sensor could be applied in a fluorescence microscopy application, making use of the sample fluorescence itself as the illumination source to measure wavefront aberrations, we found this difficult to implement in practice.…”

Roadmap on neurophotonics

“…This may in many scenarios be valid, but it is known that aberrations can change across the field. For full correction, it will be necessary either to change aberration correction rapidly during scanning using a fast adaptive element, or to use advanced AO configurations such as ‘conjugate’ or ‘multi-conjugate’ AO, where one or more correction elements are used in different positions in the optical train [67, 80]. …”