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Martin Booth"Adaptative optics for nonlinear microscopy of thick biological specimens"

Abstract :

Specimen-induced aberrations are frequently encountered in high resolution microscopy, particularly when high numerical aperture lenses are used to image deep into specimens.
These aberrations distort the focal spot causing a reduction in resolution and, often more importantly, reduced signal level and contrast. This is particularly problematic in multiphoton microscopies, such as two-photon fluorescence or harmonic generation, where the non-linear nature of the signal generation process means that the signal level is strongly affected by changes in the focal intensity. The techniques of adaptive optics have been used to measure and correct the aberrations, restoring image quality in a number of microscopes. We present here in results from adaptive multiphoton microscopes with applications in different areas. As all of these applications require focusing at depth within an inhomogeneous specimen, they suffer from the effects of aberrations. Adaptive optics can be used to compensate the aberrations, leading to improved signal levels and resolution.

Harmonic generation (HG) microscopes are capable of providing high-resolution, three-dimensional, label-free images of biological specimens. The HG signals (both second and third harmonic generation) are generated through the non-linear optical properties of the specimen, so images are obtained without the need for exogenous markers. This method is therefore particularly promising in areas such as developmental biology, where living specimens must be observed over long periods with minimal perturbation. We have developed an adaptive harmonic generation microscope and culture techniques that permit long-term imaging of mouse embryos. Compensating system induced aberrations alone significantly improved HG signals by around 50% allowing high resolution 3D imaging at a relatively low incident laser power. Correction of specimen-induced aberrations improved signal levels further, along with a significant increase in resolution. HG images from both pre and post implantation stage (0.5 - 5.5 days old) mouse embryos were obtained, revealing a wealth of structural and dynamic information about embryo development.

Selected publications

Influence of aberrations in third harmonic generation microscopy. Journal of Optics A, in press.A. Thayil, A. Jesacher, T. Wilson & M. J. Booth

Adaptive optics for direct laser writing with plasma emission aberration sensing. Optics Express, Volume 18, Issue 2, Jan 2010, 656-661.A. Jesacher, G. D. Marshall, T. Wilson & M. J. Booth

Full spectrum filterless fluorescence microscopy
Journal of Microscopy, Volume 237, Issue 1, Jan 2010, 103-109.M. J. Booth, A. Jesacher, R. Juskaitis & T. Wilson

Scientific focus :

Martin's interests lie in the application of advanced optical techniques to sub-micron scale imaging and engineering. His work includes analysis aberrations and the application of adaptive optics to microscopy, data storage, optical manipulation and fabrication technologies. Martin is Associate Editor of Optics Express.

Audrey Quessada-Vial