The current high-aspect-ratio Pancharatnam–Berry (PB)-phase metasurfaces in which vertical dimensions are much larger than the lateral dimensions are challenging to fabricate. Therefore, reducing the ...aspect ratio requirement has become a research priority. We propose a sandwich nano-fin consisting of GaN/amorphous silicon (a-Si)/GaN on a silica substrate to reduce the strict aspect ratio requirement of current PB-phase metasurfaces. The phase modulation ability and polarization conversion efficiency (PCE) of sandwich nano-fins were investigated. Compared with a conventional GaN nano-fin, the aspect ratio of sandwich nano-fin decreased from 6 to 4 under the same geometric dimension. The PCE of the sandwich nano-fin was up to 68.27%, 1.5 times higher than that of a GaN nano-fin under the same aspect ratio of 4. Moreover, after adding the a-Si layer, the overall PCE improved from 32.17 to 40.54% for the sandwich nano-fin. The sandwich structure simultaneously reduces the challenge of manufacturing and improves efficiency compared to current PB-phase metasurfaces.
A nanograting microring resonator is proposed for achieving concentric mode field profiles as the effect of guided-mode resonance. Based on a numerical simulation of the 2D finite-difference ...time-domain method, we clarified that the microring resonator with a combination of nanograting microring and sidewall blocks could generate two operating modes. The first is the optical whispering gallery mode, by which the light was in resonance inside the microring by total internal reflection and traveled in a circle around the microring. The second mode is guided-mode resonance, by which the light scattering from the grating structures is in resonance to create concentric magnetic-field distributions. The characteristics of resonance modes of the mode numbers, mode distribution, and Q factors are analyzed at the changes of the microring radius and the nanograting structures. A design of a nanograting bus waveguide with the same grating period as the nanograting microring is verified to achieve a high efficiency of the coupling ratio.
The fundamental formula in an optical system is Rayleigh diffraction integral. In practice, we deal with Fresnel diffraction integral as approximate diffraction formula. Fresnel transforms and ...inverse Fresnel transforms have been formulated systematically and defined as a bounded additive, a unitary operator in Hilbert space. To investigate the band-limited effect in Fresnel transform plane, we seek the function that its total power in finite Fresnel transform plane is maximized, on condition that an input signal is zero outside the bounded region. This problem is a variational one with an accessory condition. This leads to the eigenvalue problems of Fredholm integral equation of the first kind. The kernel of the integral equation is of Hermitian conjugate and positive definite. Moreover, we prove that the eigenfunctions corresponding to distinct eigenvalues have dual orthogonal property. By discretizing the kernel and integral range to seek the approximate solutions, the eigenvalue problems of the integral equation can depend on a one of the Hermitian matrix in finite-dimensional complex value vector space. We use the Jacobi method to compute all eigenvalues and eigenvectors of the matrix. We consider the application of the eigenvectors to the problems of the approximating any functions. We show the validity and limitation of the eigenvectors in computer simulations.
In this study, we present a new method for measuring the tilt of an image sensor to the lens. The assembly accuracy of the lens and image sensor units has a significant influence on the image quality ...for users. Any misalignment causes non-uniform defocus and distortion in the camera image. Our approach measures the tilt of the image sensor based on the amplitude (i.e., contrast or defocus) and phase (i.e., distortion) included in the camera image without special devices and precisely calibrated references. The amplitude and phase were separated in the frequency domain. The validity of the proposed method was confirmed through a numerical simulation using optical design software. The sensor tilt can be measured from the chart tilt, which does not cause any non-uniform defocus or distortion. This study achieved the simultaneous measurement and analysis of two parameters and can contribute to increase the productivity of manufacturers and improve the image quality for users.
Phase-shifting measurement with a Michelson twin interferometer, in which two interference signals concerning measurement and reference beams are generated from a common optical system ...simultaneously, is carried out with a conventional four-step interferometric method. Although the interference signal of each beam changes over time, they have a synchronous relationship and the error component can be effectively eliminated by extracting the phase difference between the measurement and reference beams.
Gastroenteritis is a clinical illness of humans and other animals that is characterized by vomiting and diarrhea and caused by a variety of pathogens, including viruses. An increasing number of viral ...species have been associated with gastroenteritis or have been found in stool samples as new molecular tools have been developed. In this work, a DNA microarray capable in theory of parallel detection of more than 100 viral species was developed and tested. Initial validation was done with 10 different virus species, and an additional 5 species were validated using clinical samples. Detection limits of 1 × 10(3) virus particles of Human adenovirus C (HAdV), Human astrovirus (HAstV), and group A Rotavirus (RV-A) were established. Furthermore, when exogenous RNA was added, the limit for RV-A detection decreased by one log. In a small group of clinical samples from children with gastroenteritis (n = 76), the microarray detected at least one viral species in 92% of the samples. Single infection was identified in 63 samples (83%), and coinfection with more than one virus was identified in 7 samples (9%). The most abundant virus species were RV-A (58%), followed by Anellovirus (15.8%), HAstV (6.6%), HAdV (5.3%), Norwalk virus (6.6%), Human enterovirus (HEV) (9.2%), Human parechovirus (1.3%), Sapporo virus (1.3%), and Human bocavirus (1.3%). To further test the specificity and sensitivity of the microarray, the results were verified by reverse transcription-PCR (RT-PCR) detection of 5 gastrointestinal viruses. The RT-PCR assay detected a virus in 59 samples (78%). The microarray showed good performance for detection of RV-A, HAstV, and calicivirus, while the sensitivity for HAdV and HEV was low. Furthermore, some discrepancies in detection of mixed infections were observed and were addressed by reverse transcription-quantitative PCR (RT-qPCR) of the viruses involved. It was observed that differences in the amount of genetic material favored the detection of the most abundant virus. The microarray described in this work should help in understanding the etiology of gastroenteritis in humans and animals.
Abstract
The purpose of this study is to clarify the long‐term evolution of land use planning and land use planning system operation, as well as the actual status of the population distribution and ...urban area formation at each stage, using the City of Sapporo as a case study. Sapporo City formulated its first basic urban plan in the 1959 Sapporo comprehensive city plan (SCCP). Since its launch in 1971, the Sapporo long‐term comprehensive plan (LTCP) was consistently employed as a masterplan, and land use plans have been established within it. SCCP emphasizes the need to control expansion of urban areas due to the crisis of sprawling urban proliferation. In response, LTCP developed a land use plan consisting of multiple cores and three types of residential areas sorted by their density. To achieve this goal, the land use planning system was revised. In this process, the basic approach to urban planning has remained consistent for almost half a century. Namely, “Positioning LTCPs as Urban Masterplan”, “Controlling the outward expansion of urban areas” and “Multi‐centered core urban structure and layout of residential areas” were continued. In parallel, the plan was flexibly modified in response to changing socioeconomic conditions.
A modular cryogenic cross-disperser MOBIUS for the Large Binocular Telescope (LBT) is being developed to produce a simultaneous zJHK spectrum with a single LUCI, the LBT Utility Cameras in the ...Infrared. Its compact and exchangeable optical design fit within the existing focal plane mask frame of the LUCI spectrograph without any other hardware modifications. This unique deployable system enables a rapid acquisition of data over a wide wavelength range to better understand the unknown objects in the universe.
We propose a new single-shot digital holography that measures the complex amplitude high precisely using a single image sensor. In this technology, a signal beam passes through a diamond-shaped ...low-pass filter, and a reference beam passes through a chessboard pattern phase-shift plate, where the phase difference between adjacent pixels is π/2. The signal and reference beams interfere, and the interference fringe is captured by a single image sensor. In a computer, an image is acquired by extracting the phase-dependent component from the interference fringe. The real and imaginary parts were obtained separately from the inside and outside of the diamond shape in the Fourier plane of the acquired image, respectively. Subsequently, the real and imaginary parts were combined to reconstruct the complex amplitude. This method can obtain the signal light in the diamond-shaped band of the Fourier plane, where the information of the signal light is concentrated generally, so this method can measure high precisely. Numerical analysis showed that the signal-to-noise ratio of the intensity and phase of this method were more than 4.8 and 2.8 dB higher, respectively, than two-step parallel phase-shift digital holography, and more than 7.3 and 4.8 dB higher, respectively, than Fourier fringe analysis, an off-axis digital holography technique. Moreover, the range of the reference intensity that maintains high-precision measurements was clarified, and the reconstruction accuracy against noise in the interference fringe or reference beam intensity was investigated.
PDF
