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We demonstrate how a novel approach for closed-loop Adaptive Optics (AO) specifically adapted to microscopy enables straightforward integration in Light-Sheet and Multiphoton microscopes, as well as fast aberration correction. We present corresponding experimental setups as well as first demonstrations of the benefits of the correction of sample-induced aberrations in zebrafish and mouse brain tissue, with the ultimate goal to enable high-speed, high-sensitivity functional imaging at large depths.

Modern bio-imaging techniques such as light-sheet, multiphoton and PALM/STORM are now aiming to image more complex biological samples at larger depth and therefore face larger-amplitude and more complex aberrations. We provide an analysis of key requirements driving optimal implementation of adaptive optics (AO) in microscopy, with a focus on wavefront modulators. We show that some specifications of wavefront modulators such as linearity, hysteresis or actuators performance & layout can end up to better AO performance in microscopy systems, when specifically optimized for such use. We then provide design details and characterization results of a newly developed deformable mirror, and report on experimental images obtained from AO-enhanced microscopes based on the device, for several modalities such as light-sheet, multiphoton or super-resolution single molecule localization systems. Finally, we provide recommendations on how to define the right set of AO components, algorithms and overall method depending on modality, instrument and sample constraints.

Shack Hartmann (SH) Wavefront Sensing (WFS) brings many advantages that has made it a standard in optical metrology, but it has long been limited by its resolution compared to other solutions, such as interferometry. We will present a new approach to the linearized focal plane technique (LIFT), formerly developed by ONERA, which is based on the combination of standard SH technology with phase retrieval algorithms. Applied on all the spots of the SH wavefront sensor microlens array, it provides information on high spatial frequencies, allows to reconstruct more modes for each microlens and results in a 16-fold improvement (4x in each transverse direction) of the sensor spatial resolution! We will present how we have optimized and validated the LIFT technology for optical metrology. We will share some measurements performed on extremely complex wavefronts. Finally, we will propose an implementation for industrial applications such as manufacturing and will describe some use cases. Benefiting from the same advantages as SH WFS -such as robustness to vibrations and atmospheric turbulence, or the ability to easily work at any wavelength- the LIFT technology presents very promising perspectives for optical and freeform metrology and can advantageously replace, at lower cost and better usability, Fizeau interferometry.

Significant efforts are currently ongoing in X-ray imaging to provide multimodal imaging systems, targeting better sensitivity and specificity for both biomedical or non-destructive testing applications. Knowing the elemental composition of specific structures, such as breast microcalcifications in mammography, would help to differentiate malign and benign tumours. Standard X-ray Phase Contrast Imaging techniques provide only qualitative information on elements with similar absorption properties. However, their chemical composition can be determined from the measurement of the phase as it is directly related to the optical index of elemental materials. We will show new experimental results obtained with an X-ray phase imaging system based on a Hartmann mask. Early data treatment succeeded in retrieving both the real and imaginary parts of the refractive index. The system demonstrates the capability to discriminate materials based on elemental composition. [ABSTRACT FROM AUTHOR]

The transient response of a deformable mirror to be used in a closed-loop adaptive-optics imaging system is modeled and evaluated. A theoretical model is developed that describes the motion of the mirror membrane. This allows an adaptive control to achieve reduced overshoot and short settling time. Applicability of the model is tested on a mirao 52-e electromagnetic deformable mirror using a specially designed high-speed adaptive-optics test bench. This test bench permits precise mirror motion measurements up to 10kHz. OCIS codes: 220.1080, 330.4460, 120.7280.

The Hartman wavefront sensor can be used for X-ray phase imaging with high angular resolution. The Hartmann sensor is able to retrieve both the phase and absorption from a single acquisition. The system calculates the shift in a series of apertures imaged with a detector with respect to their reference positions. In this article, the impact of the reference image on the final image quality is investigated using a laboratory setup. Deflection and absorption images of the same sample are compared using reference images acquired in air and in water. It can be easily coupled with tomographic setups to obtain 3D images of both phase and absorption. Tomographic images of a test sample are shown, where deflection images revealed details that were invisible in absorption. The findings reported in this paper can be used for the improvement of image reconstruction and for expanding the applications of X-ray phase imaging towards materials characterization and medical imaging. [ABSTRACT FROM AUTHOR]

The recent development of short-wavelength optics (X/EUV, synchrotrons) requires improved metrology techniques in terms of accuracy and curvature dynamic range. In this article a stitching Shack-Hartmann head dedicated to be mounted on translation stages for the characterization of X-ray mirrors is presented. The principle of the instrument is described and experimental results for an X-ray toroidal mirror are presented. Submicroradian performances can be achieved and systematic comparison with a classical long-trace profiler is presented. The accuracy and wide dynamic range of the Shack-Hartmann long-trace-profiler head allow two-dimensional characterizations of surface figure and curvature with a submillimeter spatial resolution. [ABSTRACT FROM AUTHOR]