- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Beryllium-Based Multilayer Mirrors and Filters for the Extreme Ultraviolet Range
摘要： This paper presents the first results of systematic studies of beryllium as a material for multilayer mirrors (MLM) and transmission filters (TF) for the EUV spectral range. The objective for the study is the need for the increase in reflectivity and spectral resolution of MLMs for studying the Sun's corona. We investigated Mo/Be (working wavelength is 13.2 nm), Be/Al and Be/Si/Al (17.1 and 30.4 nm) multilayers, as well as free-standing Be films. It was shown that the Be-containing MLMs have significant advantage in reflectivity while their spectral pass-band is similar to beryllium-free MLMs. Observation of the MLMs in the course of 20 months has not revealed any significant decrease in the reflection coefficient. Effect of the silicon interlayers on reflectance of Be/Al MLM is explained. Investigation of a free-standing beryllium filter of the 160 nm thickness showed that its mechanical strength is approximately at the same level as that of the aluminum filter with the same thickness. There is also high stability of the transmittance.
关键词： Multilayers,Multilayer Design,X-ray Mirrors,Space Optics
更新于2025-09-19 17:15:36
-
Nonstoichiometric amorphous silicon carbide films as promising antireflection and protective coatings for germanium in IR spectral range
摘要： A technology for preparation of amorphous nonstoichiometric hydrogenated silicon carbide (a-SixC1-x:H) films using the PE-CVD method has been developed. Such films with refractive index n = 1.8–2.1 are suitable to obtain antireflection effect on germanium in the IR spectral region. Single- and two-sided antireflection coatings of Ge enabled to increase its optical transmission up to 65% and 96% in the maximum transmission, respectively. The obtained films have good mechanical properties (H > 12 GPa, E = 100 GPa). Presence of Si-C bonds in the a-SixC1-x:H films restricts their range of application to the spectral interval 2.5–10 μm. The prepared films are uniform in composition and have high adhesion to the substrate. Variation of deposition conditions makes it possible to obtain a-SixC1-x:H films having high hardness and Young's modulus. High deposition rate, optimal optical properties of the a-SixC1-x:H films and good combination of mechanical properties for the Ge/a-SixC1-x:H film structures make them to be promising for practical application as antireflection and protective coatings for germanium.
关键词： Germanium,Antireflection coatings,Elements of IR optics,Nonstoichiometric SiC films
更新于2025-09-19 17:15:36
-
Polymer dispersed nematic liquid crystal films with conical boundary conditions for electrically controllable polarizers
摘要： Polymer dispersed nematic liquid crystal (PDNLC) ?lms with conical boundary conditions at the LC-polymer interface are considered. The conical surface anchoring with tilt angle 40° initiates forming the axial-bipolar director con?guration inside nematic droplets. This droplet structure exhibits the strong scattering of light polarized parallel to the bipolar axis. In the initial state, the bipolar axes in all droplets are oriented randomly, and therefore PDNLC ?lm scatters a light of any polarization. Electric ?eld applied along the ?lm plane orients the bipolar axes unidirectionally in the whole droplet ensemble, that results in its high polarization-dependent transmittance. Such PDNLC ?lms can be used in the electrically controllable linear polarizers characterized by 89% value of the transmittance for the perpendicular polarized light and high extinction ratio 590:1 at the electric ?eld 0.34 V/μm.
关键词： Light polarizer,Nematic droplets,Polymer dispersed liquid crystal ?lms,Scattering anisotropy,Electro-optics
更新于2025-09-19 17:15:36
-
Multimodal imaging of torpedo maculopathy including adaptive optics
摘要： Purpose: The etiology of torpedo maculopathy remains unknown, but it has been recently suggested that it could represent a persistent defect in the development of the retinal pigment epithelium. As retinal pigment epithelium and photoreceptors form a functional unit, an alteration of photoreceptor distribution or function is predictable. The aim of this study is to describe multimodal imaging, including adaptive optics, in three cases of torpedo maculopathy, and discuss its pathogenesis. Methods: Multimodal imaging is presented, including fundus photographs, optical coherence tomography, adaptive optics, autofluorescence, fluorescein angiography, and ultra-widefield retinal imaging in three cases of torpedo maculopathy. Results: An oval-shaped well-delimited chorioretinal lesion both hypopigmented centrally and with a hyperpigmented border in the temporal macula, consistent with torpedo maculopathy, was observed in three patients. Optical coherence tomography showed a preservation of the inner retina, a mild atrophy of the outer retina, an alteration of the ellipsoid zone and of the retinal pigment epithelium layer, and a neurosensory detachment. These lesions were hypoautofluorescent with a hyperautofluorescent border. Fluorescein angiography showed a hyperfluorescence by window effect. Adaptive optics imaging showed an alteration of the cone mosaic within the lesions, with a lower cone density and a higher spacing between cones. Conclusion: The alteration of the cone mosaic suggested by adaptive optics in torpedo maculopathy has never been described and could be explained by the alteration of the retinal pigment epithelium. Our results support the existing hypothesis on the pathogenesis of torpedo maculopathy that a persistent defect in the development of the retinal pigment epithelium may be responsible for this clinical entity.
关键词： retinal imaging,Torpedo maculopathy,multimodal imaging,adaptive optics
更新于2025-09-19 17:15:36
-
Anisotropic Flow Control and Gate Modulation of Hybrid Phonon-Polaritons
摘要： Light-matter interaction in two-dimensional photonic materials allows for confinement and manipulation of free-space radiation in sub-wavelength scales. Most notably, the van der Waals heterostructure comprising graphene (G) and hexagonal Boron Nitride (hBN) provides for gate-tunable hybrid hyperbolic plasmon phonon-polaritons (HP3). Here, we present anisotropic flow control and gate voltage modulation of HP3 modes in G-hBN lying on air-Au microstructured substrate. Using broadband infrared synchrotron radiation coupled to a scattering-type near-field optical microscope, we launch HP3 waves in both hBN Reststrahlen bands and observe directional propagation across in-plane heterointerfaces created at the air-Au junction. HP3 hybridization is modulated by varying the gate voltage between graphene and Au. In this case, we induce modifications to the coupling of continuum graphene plasmons with the discrete hBN hyperbolic phonon polaritons, which is interpreted as an extended Fano model. This is the first demonstration of control of polariton propagation, including a theoretical approach for a break of the reflection/transmission symmetry for HP3 modes. Our findings augment the degree of control of polaritons in G-hBN and related hyperbolic metamaterial nanostructures bringing novel insights to on-chip nano-optics communication and computing.
关键词： polaritonics,nano-photonics,graphene/boron nitride,near-field optics,hybrid polaritons,synchrotron infrared
更新于2025-09-19 17:15:36
-
Computational periscopy with an ordinary digital camera
摘要： Computing the amounts of light arriving from different directions enables a diffusely reflecting surface to play the part of a mirror in a periscope—that is, perform non-line-of-sight imaging around an obstruction. Because computational periscopy has so far depended on light-travel distances being proportional to the times of flight, it has mostly been performed with expensive, specialized ultrafast optical systems1–12. Here we introduce a two-dimensional computational periscopy technique that requires only a single photograph captured with an ordinary digital camera. Our technique recovers the position of an opaque object and the scene behind (but not completely obscured by) the object, when both the object and scene are outside the line of sight of the camera, without requiring controlled or time-varying illumination. Such recovery is based on the visible penumbra of the opaque object having a linear dependence on the hidden scene that can be modelled through ray optics. Non-line-of-sight imaging using inexpensive, ubiquitous equipment may have considerable value in monitoring hazardous environments, navigation and detecting hidden adversaries.
关键词： penumbra,ray optics,digital camera,non-line-of-sight imaging,computational periscopy
更新于2025-09-19 17:15:36
-
Effect of pad wear on tool influence function in robotic polishing of large optics
摘要： Robotic polishing can greatly improve the manufacturing efficiency of precision optics, and its tool influence function (TIF) needs to be modeled precisely for deterministic fabrication. When polishing large optics, the TIFs are significantly affected by the wear of the polishing pad, which in turn will change the material removal rate. In this paper, the generating mechanism of the pad wear is analyzed, so as to quantitatively predict the wear amount of the polishing pad under different processing parameters; consequently, the TIF error caused by pad wear can be compensated. The experimental results demonstrate that the proposed model can reliably predict the polishing pad shape and the corresponding TIF after different wearing time; henceforth, the resulting form quality and convergence rate of robotic polishing can be significantly improved.
关键词： Pad wear,Polishing,Robot,Optics fabrication,Tool influence function
更新于2025-09-19 17:15:36
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Tailoring Donor-Acceptor Pairs of Tungsten-based Transition Metal Di-Chalcogenides (TMDCs) for Improved Photovoltaic Current Generation
摘要： We present a multifunctional scheme to implement reconfigurable temporal Fourier transformation (TFT) and temporal imaging (TI) flexibly. This structure is composed of a time lens followed by a section of dispersive fiber with proper length. More specifically, the output waveforms presenting either the spectrum profile or the scaled waveform profile of the input signal are achieved by simply changing the length of the fiber, which is theoretically analyzed and experimentally verified. This proposal requires neither the use of an input dispersive device preceding the time lens nor a second time lens after the dispersion. Hence, it is a simple and practical alternative to the implementation of both TFT and TI.
关键词： fourier optics and signal processing,optics fiber communications,time lens,four wave mixing (FWM),Dispersive Fourier transformation
更新于2025-09-19 17:13:59
-
[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Distributed hydrogen monitoring with phase-sensitive optical time-domain reflectometry
摘要： We propose a distributed hydrogen sensing system based on ?-OTDR and a novel coating configuration with fiber adhesively bonding to palladium foils. An ultra-high sensitive distributed hydrogen sensing with 5 cm spatial resolution is demonstrated.
关键词： Chemical analysis,Scattering, Rayleigh,Fiber optics sensors,Fiber optics
更新于2025-09-19 17:13:59
-
[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Label-free distributed hydrogen sensing with stimulated Raman scattering in hollow-core fibers
摘要： We present the first experimental demonstration of distributed hydrogen sensing using stimulated Raman scattering in gas-filled hollow-core photonic crystal fibers. The system performances in terms of sensitivity, selectivity, dynamic range and sensing distance are discussed.
关键词： Fiber optics,Spectroscopy,Fiber optics sensors,Spectroscopy, Raman,Photonic crystal fibers
更新于2025-09-19 17:13:59