Authors: Yan Ye, Lin Sen Chen
Abstract: A novel light guide plate (LGP) with sub-micron gratings (SMGs) on its upper surface is
proposed to control the illumination angle and its initial structure of LGP is given. The periods of
SMGs are 0.651μm, 0.516μm and 0.433μm for the LED light sources transmit out vertically with
the incidence angle 45º under the total internal reflection condition. The transmission efficiencies
vary between 2% and 43% when the depth of grooves of SMGs changes between 0.05 μm and 0.9
μm by using rigorous coupled-wave theory (RCWT). The results show that the LGP utilizing the
characteristics of the SMGs can control the transmission angle and get homogeneous output.
1061
Authors: Ming Wei Ding, Zhen Kai Wan, Yong Xin Ma
Abstract: In this work, the application status and significance of Fiber Bragg Gratings（FBGs） and Three-dimensional (3-D) braided composites were briefly introduced, so were the fundamental structure of 3-D braided composites and the sensing mechanism of FBGs in them. Combined with the characteristics of 3-D braiding technology, this paper presents a primary theoretical solution for synchronously monitoring temperature and strain inside Three-dimensional (3-D) braided composites, and further analysis were made about it. It was shown by experiment that the application of FBGs in the structure health monitoring in 3-D braided composites has great potential.
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Authors: Min Jin Tang, Hui Min Xie, Jian Guo Zhu, Peng Wan Chen, Qing Ming Zhang, Xiao Jun Li
Abstract: Moiré grating is a basic optical component, and can be used in various moiré methods. The conventional grating fabrication technology is based on photolithography and holographic interferometry, however, it requires complex optical components and is very difficult to put into practice. In this study, nanoimprint lithography (NIL), or rather, hot embossing lithography (HEL), is proposed for producing high frequency grating. Compared with silicon mold, holographic moiré grating mold costs less and is not easy to break, thus is chosen to be the mold in HEL. Using this mold and the hot embossing system, the grating structure can be transferred to the polymer after HEL process. Through a number of experiments, the process parameters were optimized and gratings were successfully fabricated. The multi-scale morphology of the fabricated gratings was then characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and moiré interferometry. The microscale images observed by AFM and SEM show the regulate dots with equal spacing and the macroscale moiré patterns illuminate the excellent qualities of fabricated grating in a large area. The successful experimental results demonstrate the feasibility of the grating fabricated by HEL for the moiré measurement.
7
Authors: Xing Hui Li, Yuki Shimizu, Hiroshi Muto, So Ito, Wei Gao
Abstract: A compact optical three-axis surface encoder, which can detect displacements in the XYZ-directions simultaneously by employing a scale grating with a short pitch (0.57 μm) and a single laser beam with a short wavelength (405 nm), is described in this paper. This surface encoder mainly consists of a blue-ray laser diode, a pair of two-dimensional diffractive gratings serving as scale grating and reference grating, respectively, and two quarter photodiodes (QPD) utilized for detecting output optical density. The displacements of the scale grating along X-, Y- and Z-directions are measured by analyzing interference signals caused by the phase shifts and light path difference of diffracted beams from the scale grating and reference grating. Basic measurement principle is illuminated, a compact surface encoder is designed and evaluation experiments are carried out.
913
Authors: Bing Cao, Gui Ju Zhang, Chin Hua Wang, Jian Feng Wang, Ke Xu
Abstract: In this paper, novel active narrowband notch filters with triple-layer composite nanostructures on a GaN-based LED are obtained by mainly adjusting the grating period and duty cycle. The three layers consist of two dielectric thin layers and one metallic / dielectric grating layer. The grating layer composes of subwavelength period and thickness rectangular stripes, which lies between a transition layer and a protecting layer. Line-width and attenuation peak properties of the resonance filters are calculated and investigated by using a full vector implementation of Rigorous Coupled Wave Analysis (RCWA) algorithm. It is shown that the grating period can significantly change the filter peak wavelength, and the grating duty cycle heavily changes the filter line-width. The filter attenuation peak has a red shift with 23.3nm as the grating period increases 18nm. The FWHM (Full Width at Half Maximum) of the filter reduces from 1.9nm to 0.28nm as the duty cycle changes from 0.55 to 0.3, which compressed more than six times. Moreover, thickness of each composite nanostructure layer can also affect the narrowband width and peak wavelength of the filter. The results provide guidance in designing, optimizing and fabricating such an active narrowband filter with highly integrated photonic devices.
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