Tunable lenses: Dynamic characterization and fine-tuned control for high-speed applications

Tunable lenses are becoming ubiquitous, in applications including microscopy, optical coherence tomography, computer vision, quality control, and presbyopic corrections. Many applications require an accurate control of the optical power of the lens in response to a time-dependent input waveform. We present a fast focimeter (3.8 KHz) to characterize the dynamic response of tunable lenses, which was demonstrated on different lens models. We found that the temporal response is repetitive and linear, which allowed the development of a robust compensation strategy based on the optimization of the input wave, using a linear time-invariant model. To our knowledge, this work presents the first procedure for a direct characterization of the transient response of tunable lenses and for compensation of their temporal distortions, and broadens the potential of tunable lenses also in high-speed applicationsVA and EL acknowledge financial support from Comunidad de Madrid and Marie Curie Action of the European Union FP7/2007-2013 COFUND 291820; XB from Comunidad de Madrid Doctorado Industrial IND2017/BMD-7670; EL from Spanish Government Ramon y Cajal Program RyC-2016-21125; EG from Spanish Government Torres-Quevedo Program PTQ-15-07432; LS from EU H2020 SME Innovation Associate GA-739882; EG from EIT Health; SM from ERC Grant Agreement ERC-2011-AdC 294099 and Spanish Government Grants FIS2014-56643-R; SM and CD from Spanish Government Grant FIS2017-84753-R; and CD from DTS16-0012

Grafting of Metallacarboranes onto Self-Assembled Monolayers Deposited on Silicon Wafers

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A boron-boron linked large metallacarborane cluster: Characterization and X-ray structure of 8.9 '-[closo-{3-Co(eta(5)-C5H5)-1,2-C2B9H10}]2

The 8,9'-[closo-{3-Co(eta(5)-C5H5)-1,2-C2B9H10)](2) (1) species, in which two large closo-CoC2B9 sub-clusters are connected by a B-B bond, is unexpectedly obtained from the reaction of closo-[3-Co(eta(5)-C5H5)-1,2-C2B9H11] with sulfur in the presence of aluminium chloride under reflux conditions. The solid state conformation of 1 seems to be the result of a pair of intramolecular C-H center dot center dot center dot H-B dihydrogen bonds between the protonic H atoms of the C5H5 fragment of a sub-cluster and the hydridic H atoms of the C2B9H11 fragment in the other sub-cluster in 1

Vision is protected against blue defocus

Abstract Due to chromatic aberration, blue images are defocused when the eye is focused to the middle of the visible spectrum, yet we normally are not aware of chromatic blur. The eye suffers from monochromatic aberrations which degrade the optical quality of all images projected on the retina. The combination of monochromatic and chromatic aberrations is not additive and these aberrations may interact to improve image quality. Using Adaptive Optics, we investigated the optical and visual effects of correcting monochromatic aberrations when viewing polychromatic grayscale, green, and blue images. Correcting the eye’s monochromatic aberrations improved optical quality of the focused green images and degraded the optical quality of defocused blue images, particularly in eyes with higher amounts of monochromatic aberrations. Perceptual judgments of image quality tracked the optical findings, but the perceptual impact of the monochromatic aberrations correction was smaller than the optical predictions. The visual system appears to be adapted to the blur produced by the native monochromatic aberrations, and possibly to defocus in blue

Deciphering the role of the cation in anionic cobaltabisdicarbollide clusters

International audienceThe counter cation influence (H+, Na+, K+ and Li+) on the aggregates formation in aqueous solution of the salts of cobaltabisdicarbollide [1]- and its derivatives (monoiodinated [I-1]- and diiodinated [I2-1]-) has been studied by means of 11B{1H} and 1H{11B} NMR spectroscopy. 11B{1H} NMR spectrum of M[1] (M= alkali or H+) in water exhibits much wider signals than in an organic solvent because organic solvents (acetone) cause disaggregation. The wider resonances are found at concentrations larger than 10 mM while the sharpest signals are found below 10 mM, in which a large fraction of H[1] is in monomeric form and only a small fraction of H[1] participate in the formation of vesicles that has been visualized by CryoTEM. 11B{1H} NMR of H[1] at concentrations lower than 10 mM corresponds to the monomer and the phase transition that is observed is due to the monomer to micelles transformation. The 11B-NMR is, therefore, an excellent probe to visualize the phase transition between vesicles/monomer and micelles/monomer that appears between 10 and 20mM, for all tested cations. The 1H{11B} NMR spectra contribute interesting complementary information to the one retrieved from the 11B{1H} NMR, particularly in what concerns to dihydrogen bonds formation, C-H···H-B. These results have been compared with available crystal structures, which reveal the presence of such intermolecular dihydrogen bonds as responsible of the aggregates formation of [1]- in water. Computational analysis of the intermolecular interactions and self-assembly of the anions [1]- [I2-1]- are presented

Carboranyl Substituted Siloxanes and Octasilsesquioxanes: Synthesis, Characterization, and Reactivity.

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