Diffraction Gratings (diffraction + grating)

Distribution by Scientific Domains


Selected Abstracts


Dendritic polyisophthalate endcapped with naphthyl groups for holographic recording,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2004
Huiguang Kou
Abstract A novel dendritic polyisophthalate with 12 naphthyl groups at the chain ends was synthesized from 5-hydroxyisophthalic acid as an AB2 monomer, 1,3,5-benzenetricarbonyl trichloride as an ,initiator core' molecule, and , -naphthol as an endcapping reagent, via a stepwise growth process. An average molecular weight of 2860,g,mol,1, and a refractive index of 1.618 at 650,nm were obtained by gel permeation chromatography and ellipsometry, respectively. A photopolymerizable recording dry film incorporating this dendrimer as a polymeric binder was used for holographic recording. Diffraction gratings with diffraction efficiency exceeding 80%, together with a modulation index of 10,2 were obtained. Copyright © 2004 John Wiley & Sons, Ltd. [source]


Sub-100-nanometre resolution in total internal reflection fluorescence microscopy

JOURNAL OF MICROSCOPY, Issue 1 2008
M. BECK
Summary Combining total internal reflection fluorescence microscopy with structured illumination allows optical wide-field imaging with sub-100-nanometre resolution. We present a novel objective-launch set-up for standing wave illumination that takes advantage of a tunable transmission diffraction grating and transparent phase shifters actuated by electro-active polymers to control the excitation pattern in three dimensions. Image acquisition is completed in less than 1 s. To reconstruct the extended image spectrum, we apply a new apodization function that results in a lateral resolution of 89 nm for green emission wavelength. [source]


Determination of carrier diffusion coefficient and lifetime in single crystalline CVD diamonds by light-induced transient grating technique

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2010
T. Malinauskas
Abstract We report on a contactless, all-optical study of carrier diffusion and recombination kinetics in single-crystalline diamond layers using the light-induced transient grating (LITG) technique. Decay times of transient diffraction grating yielded carrier lifetime of ,R,,,3,ns and bipolar diffusion coefficient Da,=,12,cm2/s at 300,K. The latter value of Da was found to be 4,5 times lower than the ambipolar diffusivity based on electron and hole mobilities, measured by photo-electrical time-of-flight (ToF) technique. This discrepancy was attributed to the bandgap renormalization at high excess carrier densities and its impact on carrier diffusion. The significant decrease of low temperature diffusivity pointed out to a contribution of many-body effects which are tentatively attributed to the formation of electron,hole liquid (EHL) at T,<,150,K. [source]


Fine Structure of Elytral Punctures and Diffraction Gratings in Korean Sericinae (Coleoptera, Melolonthidae)

ENTOMOLOGICAL RESEARCH, Issue 2 2003
Jin Ill KIM
ABSTRACT The surface structures of the elytra in twenty two species belonging to the subfamily Sericinae (Coleoptera, Melolonthidae) were observed by scanning electron microscopy. For viewing specific characters, elytral punctures and diffraction gratings on interstitial surface were focused on. The elytral punctures of observed Sericid beetles have three representative forms: horseshoe, ocellus, and crease types. The diffraction gratings of the elytra show three distinctive patterns: regular and parallel, discontinued, and interconnected and curved. These patterns of elytral punctures and diffraction gratings considered to be useful for identification. [source]


Light-Induced Reorganization in Self-Assembled Liquid Crystal Gels: Electrically Switchable Diffraction Gratings,

ADVANCED MATERIALS, Issue 17 2003
Y. Zhao
Electrically switchable diffraction gratings can be formed in the self-assembled cholesteric liquid crystal gels prepared using an azobenzene-containing gelator. The grating formation (see Figure) results from a light-induced reorganization process in these materials, which leads to the removal of the nanometer-sized fibrous aggregates of the gelator from the irradiated area to the non-irradiated area. [source]


Cover Picture: Laser & Photon.

LASER & PHOTONICS REVIEWS, Issue 1 2010
Rev. 4(1)/2010
When a laser pulse propagates through a pair of diffraction gratings, its carrier-envelope phase depends strongly on the separation of gratings. This effect has been used to stabilize the carrier-envelope phase in chirped pulse laser amplifiers. (Picture: E. Moon et al., pp. 160,177, in this issue) [source]


Light trapping in organic solar cells

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2008
Michael Niggemann
Abstract One key problem in optimizing organic solar cells is to maximize the absorption of incident light and to keep the charge carrier transport paths as short as possible in order to minimize recombination losses during the charge carrier extraction. The large versatility of organic semiconductors and compositions requires specific optimization of each system. Due to the small thickness of the functional layers in the order of several ten nanometres, coherent optics has to be considered and therefore interference effects play a dominant role. Here we present and discuss concepts for light trapping in organic solar cells. These are wide gap layers in planar solar cells, folded solar cell architectures benefiting from the illumination under inclined incident angles and multiple reflections and absorptions as well as diffraction gratings embossed into the photoactive layer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Angle-resolved Mueller polarimeter using a microscope objective

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2008
S. Ben Hatit
Abstract A new Mueller polarimeter based on liquid crystals and a microscope objective is presented for the characterization of diffraction gratings in a conical diffraction mounting. Fast measurements of complete Mueller matrices over a range of polar angles , (0,60°) and azimuthal angles , (0,360°) are achieved without mechanical movements. The polarization states generator and analyzer are based on nematic liquid crystals. The angular range is achieved through focalization of light over the measured sample with a microscope objective of high numerical aperture and imaging of the objective's back Fourier plane on a CCD. Results on isotropic samples and diffraction gratings are shown. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Phase contrast X-ray imaging of large samples using an incoherent laboratory source

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2007
C. Kottler
Abstract An interferometric method to record quantitative X-ray phase contrast images has been developed that can be used at polychromatic and incoherent X-ray sources such as laboratory tubes. With respect to previously presented results, in this work we report on recent developments and results that have been achieved in view of potential future applications such as in medicine or biology. In particular, due to improvements in the fabrication process large area diffraction gratings with high aspect ratio were achieved. Thereby, the field of view of the interferometer has been drastically increased to 64 × 64 mm2 and the design value of the photon energy for the gratings could be increased up to 28 keV. Moreover, the use of a Medipix2 single photon-counting pixel detector shows a considerable improvement in image quality and sensitivity over the integrating detector used so far. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]