We propose a structured illumination microscopy method to combine super resolution and optical sectioning in three‐dimensional (3D) samples that allows the use of two‐dimensional (2D) data ...processing. Indeed, obtaining super‐resolution images of thick samples is a difficult task if low spatial frequencies are present in the in‐focus section of the sample, as these frequencies have to be distinguished from the out‐of‐focus background. A rigorous treatment would require a 3D reconstruction of the whole sample using a 3D point spread function and a 3D stack of structured illumination data. The number of raw images required, 15 per optical section in this case, limits the rate at which high‐resolution images can be obtained. We show that by a succession of two different treatments of structured illumination data we can estimate the contrast of the illumination pattern and remove the out‐of‐focus content from the raw images. After this cleaning step, we can obtain super‐resolution images of optical sections in thick samples using a two‐beam harmonic illumination pattern and a limited number of raw images. This two‐step processing makes it possible to obtain super resolved optical sections in thick samples as fast as if the sample was two‐dimensional.
Lay description
Structured illumination microscopy is a method used to build optical sections that reveal details closest together than the fundamental Abbe resolution limit. Fifteen images are classically required to compute the final super resolved section when the sample is three dimensional, while only seven are sufficient in the two dimensional case. The need for extra images in the three dimensional case is explained by the necessity to disentangle the information contained in optical section from the out of focus content.
In this paper we show that by estimating and subtracting the out of focus content from the images before combining, then only seven images are sufficient to build super resolved optical sections of three dimensional samples. The main difficulty lies in the evaluation of the weight of the out of focus part.
We evaluate the efficiency of our approach using simulated data. We show that it is insensitive to the illumination pattern structure and contrast.
We then present results obtained in a 100 micrometre thick C‐elegans worm. We compare optical sections computed using a limited number of images, with or without background subtraction, that clearly demonstrate the enhancement brought by our approach.
Structured illumination microscopy is a recent imaging technique that aims at going beyond the classical optical resolution by reconstructing high-resolution (HR) images from low-resolution (LR) ...images acquired through modulation of the transfer function of the microscope. The classical implementation has a number of drawbacks, such as requiring a large number of images to be acquired and parameters to be manually set in an ad-hoc manner that have, until now, hampered its wide dissemination. Here, we present a new framework based on a Bayesian inverse problem formulation approach that enables the computation of one HR image from a reduced number of LR images and has no specific constraints on the modulation. Moreover, it permits to automatically estimate the optimal reconstruction hyperparameters and to compute an uncertainty bound on the estimated values. We demonstrate through numerical evaluations on simulated data and examples on real microscopy data that our approach represents a decisive advance for a wider use of HR microscopy through structured illumination.
The second generation of Gravitational waves detectors are kilometric Michelson interferometers with additional recycling Fabry–Perot cavities on the arms and the addition of two more recycling ...cavities to enhance their sensitivity, with the particularity that all the mirrors are suspended. In order to control them a new technique, based on the use of auxiliary lasers, has been developed to bring the interferometer to its working point, with all the cavities on their resonance, in an adiabatic way. The implementation of this technique in Advanced Virgo is under preparation and the propagation of a stable laser through a 3-km optical fibre is one of the most problematic issues. A new technique of active phase noise cancellation based on the use of Electro Optical Modulators has been developed, and a first prototype has been successfully tested.
Describes a compensated, common path, lateral shearing interferometer that allows fast two-dimensional measurements of the optical thickness of transparent plates or discs. It provides accurate ...results even when heterogeneous residual birefringence is present in the sample. Two examples of the measurement procedure are given: on a 5.4 cm thick plane-plane super-polished fused silica substrate, originally designed to be the beamsplitter of the Virgo gravitational wave interferometer; and on a 2 mm thick float glass window. (Original abstract - amended)
The Virgo interferometer is one of the big observatories aimed at detecting gravitational waves. This paper will describe the Virgo + upgrades and the commissioning work performed between the first ...Virgo science run (VSR1) and the second Virgo science run (VSR2). Some first results of VSR2 will be discussed, which was recently started with a good duty cycle and an inspiral range for the detection of binary neutron--star inspirals of 10 Mpc. To conclude, an outlook will be given on some future upgrades of the detector.
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