Adaptive Optical Microscopy Systems: Unifying theory, practice and applications

Informations projet

AdOMiS

N° de convention de subvention: 695140

DOI

10.3030/695140

Projet clôturé

Date de signature de la CE 8 Juin 2016

Date de début 1 Septembre 2016

Date de fin 31 Août 2022

Financé au titre de

• EXCELLENT SCIENCE - European Research Council (ERC)

Coût total

€ 3 234 789,00

Contribution de l’UE

€ 3 234 789,00

Coordonné par

THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD
United Kingdom

Periodic Reporting for period 4 - AdOMiS (Adaptive Optical Microscopy Systems: Unifying theory, practice and applications)

Période du rapport: 2021-03-01 au 2022-08-31

Résumé du contexte et des objectifs généraux du projet

Fluorescence microscopy is a central tool for investigation of molecular structures and dynamics that take place in biological cells and tissues. Coupled with progress in labeling methods that highlight molecules and features of interest, these microscopes permit observation of biological structures and processes with unprecedented sensitivity and resolution. Such microscopes are vital tools in development of our understanding of the functioning of cells, tissues and organisms, with benefits ranging from better understanding of the nature of life to enabling medical advances.

These microscopes have been enabled by the engineering development of diverse optical systems that provide different capabilities for the imaging toolkit. However, all of these methods can suffer from the effects of the variable optical properties of biological specimens. The optical distortions – or aberrations – introduced by these specimens blur the images, reducing image contrast and resolution, which limits the range of applications. Adaptive optics (AO) methods were originally developed for astronomical telescopes, in order to compensate for the blurring effects of turbulence in the atmosphere. More recently, they have been developed to overcome aberration problems in microscopes, recovering the optimal imaging performance. This technology has always shown promise to improve virtually all types of research or commercial microscopes. This project addressed several significant challenges that were limiting the potential of adaptive optics to be widely implemented in routine imaging.

The AdOMiS project concerned the development of a next generation of adaptive optics technology for microscopes. Many previous advances have been made through development of bespoke AO solutions to individual imaging tasks. However, the diversity of microscopy methods meant that individual solutions were often not translatable to other systems. This project involved the creation of theoretical and practical frameworks that tied together AO concepts and provided a suite of scientific tools with broad application. This systems approach encompassed theoretical modelling, optical engineering and the requirements of biological applications.

The new technology developed in this project enabled deeper imaging inside specimens, so that microscopes could image more of a specimen. It enabled faster imaging – through improved efficiency, it was possible to observe fast biological processes in greater detail. It provided improvement to super-resolution microscopes – these super-resolution methods reveal details that are too small to detect in a conventional microscope, but their sensitivity to aberrations limits their application; adaptive optics improved the performance of these methods to make them more broadly applicable.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

Several microscope systems were built to act as test-beds for new adaptive optics methods and as systems for demonstration of newly-enabled applications. This includes two confocal and multiphoton laser scanning microscopes, which are the most common high-resolution imaging tools in biological research, and wide-field microscopes for fast volumetric imaging. We also built a new generation of super-resolution microscopes with adaptive optics capability. Other systems were introduced for the calibration an optimisation of adaptive optics elements. These test-beds were used to extend beyond phase calibration to polarisation, which is required for several microscope applications.

Significant effort has been in the development of mathematical models of aberration measurement and correction. A framework was developed to tie together existing diverse methods and to permit side-by-side comparisons of effectiveness in different microscope applications. This has shown which aberration correction methods are more applicable in certain operating regimes than other, which will enable future users to tailor their methods more precisely to applications. Further theoretical development has been undertaken to model aberrations in complex microscope systems, including so-called 4-pi systems that use dual opposing objective lenses. New mathematical representations and control strategies enable the implementation of adaptive optics in these advanced microscopes. We introduced a novel approach to image-based adaptive optics by designing bespoke neural-network-based control systems whose performance far exceeded that of conventional methods. These methods are readily extendable to a wide range of microscopes and imaging applications.

We also moved the direction of research into other areas of imaging where adaptive optics can provide benefit. An area of major success is in endoscopy, where we have implemented imaging systems through multimode fibres for probing deep within living brain tissue. We have also investigated the complex optical effects in graded index (GRIN) lenses, which are commonly used for endoscopic imaging, including in medical applications. We introduced the concept of vectorial adaptive optics, in which both polarisation and phase errors could be simultaneously optimised.

We worked with research partners to build up capabilities in biomedical applications, which allowed broader exploitation of our new methods. Through this work, we were able to illustrate system capabilities in applications in cell biology, immunology, and neuroscience, showing the wide benefits of these new methods.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The AdOMiS project generated the underlying adaptive optics technology that will underpin a wide range of advanced microscopes. These microscopes will be able to image at increased depths in specimens, at greater efficiency and higher speed. By improving the capabilities in super-resolution microscopes, we have opened up new areas of application, which will improve our knowledge of biological function.

One of the key advances was a comprehensive theoretical understanding that brought together diverse methods of adaptive optics and permitted comparison between different technologies. This was developed into a practical framework for implementation of adaptive optics across a wide range of microscope methods and applications. This framework provides guidance to developers as to the optimum methods that should be employed for particular applications. We generated tools based around machine-learning enabled aberration control that improves the ability to measure aberrations with higher sensitivity and over a greater range of operation than was previously possible.

The project also produced tools for the generation and control of light, both for correction of aberrations through adaptive optics, but also for wider applications. This includes the adaptive control of the light’s polarisation, which is important for many imaging applications, and also the control of ultra short light pulses, which are used in many microscopes.

New and unexpected applications have opened up that permit deeper imaging inside tissues, which is particularly useful for neuroscience imaging. A suite of endoscopic and microscopic tools were made available to provide more detail from deep within brain tissue. This will enable neuroscientists to understand more about the nature of operation of brains by observing the connections between neurons and the development of networks in the brain.