Search results for "photonics"
showing 10 items of 802 documents
Predictability of intraocular lens power calculation after small-incision lenticule extraction for myopia
2019
PURPOSE To evaluate and compare the predictability of intraocular lens (IOL) power calculation after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism. SETTING Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany. DESIGN Retrospective comparative case series. METHODS Preoperative evaluation included optical biometry using IOLMaster 500 and corneal tomography using Pentacam HR. The corneal tomography measurements were repeated at 3 months postoperatively. The change of spherical equivalent due to SMILE was calculated by the manifest refraction at corneal plane (SMILE-Dif). A theoretical model, involving the virtual implantation of the same…
Residual astigmatism produced by toric intraocular lens rotation.
2010
Purpose To analyze changes in the eye’s refractive properties when a toric intraocular lens (IOL) rotates. Setting Fundacion Oftalmologica del Mediterraneo, Valencia, Spain. Design Experimental study. Methods The matrix definition of astigmatism was used in this theoretical study and compared with another vector representation. Two methods were compared: (1) The cylinder, C, resulting from the addition of 2 cylinders C1 and C2 whose axes form an angle a, is obtained by the addition of 2 vectors of values C1 and C2 forming an angle 2a; (2) the power matrix, F, of a thin astigmatic dioptric system that decomposes naturally into 3 orthogonal components: the purely spherical part Fnes, the orth…
Far-Field Optical Control of a Movable Subdiffraction Light Grid
2012
International audience; We demonstrate experimentally a subdiffraction light pattern, with a period down to 150 nm, at the surface of an optimized silicon nanostructured thin film. We show, using near-field and far-field characterization, that this subdiffraction pattern can be translated and rotated just by changing the illumination angle. The movable high frequency light pattern paves the way for subdiffraction resolution surface imaging microscopy without scanning near-field probes.
Analysis of multiple internal reflections in a parallel aligned liquid crystal on silicon SLM
2014
Multiple internal reflection effects on the optical modulation of a commercial reflective parallel-aligned liquid-crystal on silicon (PAL-LCoS) spatial light modulator (SLM) are analyzed. The display is illuminated with different wavelengths and different angles of incidence. Non-negligible Fabry-Perot (FP) effect is observed due to the sandwiched LC layer structure. A simplified physical model that quantitatively accounts for the observed phenomena is proposed. It is shown how the expected pure phase modulation response is substantially modified in the following aspects: 1) a coupled amplitude modulation, 2) a non-linear behavior of the phase modulation, 3) some amount of unmodulated light…
Evaluating plasmonic transport in current-carrying silver nanowires
2013
cited By 1; International audience; Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends …
Simultaneous remote extraction of multiple speech sources and heart beats from secondary speckles pattern
2009
The ability of dynamic extraction of remote sounds is very appealing. In this manuscript we propose an optical approach allowing the extraction and the separation of remote sound sources. The approach is very modular and it does not apply any constraints regarding the relative position of the sound sources and the detection device. The optical setup doing the detection is very simple and versatile. The principle is to observe the movement of the secondary speckle patterns that are generated on top of the target when it is illuminated by a spot of laser beam. Proper adaption of the imaging optics allows following the temporal trajectories of those speckles and extracting the sound signals ou…
Birth of the Localized Surface Plasmon Resonance in Monolayer-Protected Gold Nanoclusters
2013
Gold nanoclusters protected by a thiolate monolayer (MPC) are widely studied for their potential applications in site-specific bioconjugate labeling, sensing, drug delivery, and molecular electronics. Several MPCs with 1-2 nm metal cores are currently known to have a well-defined molecular structure, and they serve as an important link between molecularly dispersed gold and colloidal gold to understand the size-dependent electronic and optical properties. Here, we show by using an ab initio method together with atomistic models for experimentally observed thiolate-stabilized gold clusters how collective electronic excitations change when the gold core of the MPC grows from 1.5 to 2.0 nm. A …
Optimization of a polarization imaging system for 3D measurements of transparent objects
2009
This paper presents a multispectral imaging system for 3D reconstruction of transparent objects based on "shape from polarization" technique. The originality of this work relies on a multispectral active lighting system which enables to cope with the two ambiguities on the zenith angle and azimuth angle. A calibration step allows optimising the polarimetric measurements. Example of a reconstructed transparent object is presented.
Subjective Refraction Techniques in the Frame of the Three-Dimensional Dioptric Space
2001
A novel heuristic approach to the well-known representation of the dioptric power in a three-dimensional space is presented. It is shown how this theoretical framework is ideal for discussing the principles of several subjective refraction methods. In particular, this formalism is used to justify the stenopaic slit refraction, the Barnes subjective refraction technique, and the Jackson cross-cylinder procedure. In view of this analysis, some modifications to the traditional procedures are proposed.
Lateral magnification matrix from the dioptric power matrix formalism in the paraxial case.
2012
Background Previous studies have highlighted that power matrices fully characterize the concept of dioptric power of any astigmatic surface. Thus, the basic equations in physiological optics can be generalized using the matrix formalism of the dioptric power. Among others, lateral magnification has also been interpreted as a matrix but mainly concerning magnification modification induced by spectacle correction of refractive error. Purpose To provide a fresh look into a novel paraxial formulation for the assessment of the lateral magnification using power matrices and in presence of astigmatism for thin and thick imaging systems in general. Methods Linear optics provides the frame to genera…