Papers by Keyword: Reflectivity

Abstract: The idea of non-uniform film was applied: the multilayer uniform films could be equivalent to a non-uniform film layer so that the non-uniform film system could be converted to the uniform film system and the index of refraction of each layer could be gotten by the equivalent method. The relevant design and reasonable optimization for the film system were conducted through computer so as to get a film system whose transmittance is greater than 95% with the incidence angle within 520-640 and wavelength at 420-670nm.

Abstract: In this research, a triangular two-dimensional (2D) photonic crystal (PC) was hypothetically introduced into the active layer of a PbS quantum dots (QDs) electroluminescent (EL) device. The attributes of the photonic band gap effect and diffraction effect were considered and evaluated for device performance improvement. We designed and optimized the 2D-PC structure parameters to enhance the emission intensity at wavelength 1124 nm. The optimal structure parameter of PC is determined by normalized radius of r/a=0.49 and lattice constant of a=540 nm when the thickness of PC slab h is 74 nm. The 3D stimulation view of light propagation validates and supports the proposed strategy. The results provide a theoretical prediction for ideal PbS QDs-based EL device.

Abstract: This paper introduces a new standard reflecting plate’s manufacture, which is used to calibrate the measurement system for radar absorbing materials in 3 mm band. The new standard plate is designed and employed with two reflecting surface, one is a plane, the other one is curve, and metal with high permittivity. It has the nominal reflectivity of -15dB, -10dB, -5dB and has the advantages of high stability, easy manufacture and convenient usage

Abstract: The lattices motion equation and Born-Huang equation was established with the framework of modified random-element-isodisplacement (MREI) model, and the relationship of dielectric constants of lattice vibration and FT-IR reflectivity spectra in ternary mixed crystals ZnS1-xSex with the changes of composition x are discussed. The two-mode behavior of long-wave length optical phonon was studied, and the relation of TO-phonon frequency and LO-phonon frequency with composition was obtained.

Abstract: Make nano-scale Al doped with SiC by combustion synthesis with Si, C and Al powder as the raw materials. This kind of nano-scale Al doped with SiC boasts high infrared radiance, and thus can be used for energy conservation of thermal equipments at 800~1500°C. Details include: adopt the synthetize nano ceramic powder of high emissivity at low expense to compound coatings, and deposit the coating at the inwall of thermal kilns to make perfect combination so as to keep high emission rate for the purpose of saving energy in the subsequent process of actual use.

Abstract: This work was aimed at manufacturing the microcellular foam polypropylene for the applications of reflective film with chemical foaming agent or supercritical carbon dioxide. The effects of processing conditions such as the composition of foaming agent during chemical process, the foaming temperature and saturation pressure in physical process on the microcellular structures and the reflectivity as well as the volume expansion ratio were investigated.

Abstract: This paper proposes multipoint optical fiber sensing system based on fiber Bragg grating (FBG) sensor array. The low reflectivity FBG sensors having the same Bragg wavelength are connected cascaded in the same fiber line as the sensing elements of optical fiber sensing system. This can increase the monitoring points and reduce manufacturing costs of FBG sensor. To verify the effectiveness, the system simulator based on equivalent circuit model by microwave technology was developed. Simulation result shows that though multi-reflections can be caused by FBG sensors with the same Bragg wavelength connected cascaded in the same line, the effect may become weak as reflectivity of FBG sensors are reduced to 0.02.

Abstract: This paper introduces the manufacture of a new standard reflecting plate, which is used to calibrate the measurement system of radar absorbing materials in 3 mm band. The new standard reflecting plate is designed and employed with the structure of truncated pyramid and metal with high permittivity. It has the nominal reflectivity of-5dB, -10dB, -15dB and has the characteristics of high stability, easy manufacture and convenient usage.

Abstract: Aluminum films with high reflectivity and low absorption in the visible wavelength region have been widely used in optical applications. In this investigation, aluminum films were deposited on the glass substrate at various temperatures by electron-beam vapor deposition. The reflectivity of the Al thin film was measured by a Perkin-Elmer Lambda spectrophotometer in the wavelength region of 450-680 nm. The effects of the temperature and humidity on the reflectivity of the Al film were examined. Experimental results show that the reflectivity of Al films is increasing with the increase of substrate temperature.

Abstract: In this paper, we used spectrophotometric measurement to get the reflectance values of experimental samples and discussed relation between the reflectivity and the moisture content. By measured curves of reflectivity and the wavelength of 47 samples from 0 to 30 minutes we had found that the reflectance difference was the largest when the wavelength in the 600-700nm wavelength,it could help us to distinguish dynamic surface moisture performance at different time points, so, the paper had selected the reflectivity in wavelength 650nm as the feature value. Using the reflectance had established the linear model of moisture content, the results showed that: R² value of the determination coefficient of the linear regression model is 0.9979, almost close to 1, it had indicated that the reflectivity as the feature value could be used to predict fabric moisture content.