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期刊信息/Journal information
Optical review
Optical Society of Japan
Optical review

Optical Society of Japan

1340-6000

Optical review/Journal Optical reviewISTPSCI
正式出版
收录年代

    A single backlit image enhancement method by image fusion with a weight map for improvement of dark area's visibility

    Akai, MasatoUeda, YoshiakiKoga, TakanoriSuetake, Noriaki...
    11页
    查看更多>>摘要：Images captured in backlit conditions (i.e., backlit images) often have a vast difference in lightness between bright and dark areas. In such a dark area in an image, the visibility becomes extremely low, making it indistinct to recognize the subject. Sufficient image quality cannot be obtained by simply applying a general image enhancement method to such a backlit image. Many methods specializing in improving the image quality of backlit images have been proposed to cope with this problem. Although these methods can effectively improve dark areas' visibility compared to general image enhancement methods, the enhancement process causes artifacts in bright areas. In this paper, we propose a single backlit image enhancement method that effectively improves only the visibility of dark areas while suppressing over-enhancement and artifacts. In the proposed method, the lightness of the output image is calculated by the weighted sum of the input lightness image and the enhanced lightness image based on a weight map. The enhanced lightness image is calculated by alpha-blending two lightness-converted images obtained by gamma conversion and histogram equalization of the input lightness image. The weight map is calculated based on edge-preserving smoothing with a guided filter of a binarized input lightness image obtained using Otsu's method. The experiment shows the proposed method's effectiveness by quantitatively and qualitatively comparing conventional image enhancement methods and the proposed method using various backlit images.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Research on three-core photonic crystal fiber plasmonic sensor based on surface plasmon resonance with three V-groove microfluidic channel

    Jiao, ShengxiLi, XinzhiRen, XiaoleiYang, Hanrui...
    11页
    查看更多>>摘要：A three-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) has been designed with silver film coated on the inner wall of a microfluidic detection channel with three V-grooves. The coupling characteristics and sensing properties of the proposed sensor are analyzed numerically using the full vector finite element method (FEM). The loss spectra and the sensing performance are found to be effectively tuned by the structure parameters of the plasmonic sensor. The simulation results show that an average wavelength sensitivity (WS) of 5413.3 nm/RIU is reached when the refractive index (RI) of the analyte lies in the range from 1.330 to 1.370, while the maximum WS achieves is 11400 nm/RIU, which occurs when the RI varies between 1.365 and 1.370, corresponding to a maximum RI resolution of 8.77 x 10(-6) RIU. This is thus extremely sensitive to changes in analyte RI in the microfluidic channel.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Tunable comb-like optical transmission spectrum resulting from equilateral polygonal networks

    Xu, XiaohuiWang, YuYe, Jiamin
    6页
    查看更多>>摘要：The photonic band structures of waves in configuration-periodic equilateral polygonal networks (EPNs) are studied in the paper. The results indicate that comb-like optical transmission spectrum can be realized by EPNs.The number, width, and range of continuous equidistant frequency bands can be controlled conveniently by adjusting the waveguide length and the unit cell numbers of upper arm. Those comb-like frequency bands have potential in the design optical narrowband filters, multichannel filters, and optical switching.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Batch skeleton extraction from ESPI fringe patterns using pix2pix conditional generative adversarial network

    Zhang, ZijianWang, HuayingZhu, QiaofenWang, Xue...
    9页
    查看更多>>摘要：The key to measurement by electronic speckle pattern interferometry (ESPI) is to obtain accurate phase information from the ESPI fringe patterns. We propose a fast batch skeleton extraction method for ESPI fringe patterns using the pix2pix conditional generative adversarial network (pix2pix cGAN). The network is trained by ESPI fringe patterns and complete skeleton images, and the trained network can quickly extract skeletons; it took 11.7 s to extract the skeletons of 200 experimental ESPI fringe patterns. Compared to the fringe skeleton method, cycle GAN method, and U-net method, our method can obtain accurate, complete, and smooth skeletons faster. In addition, for some broken ESPI fringe patterns, the traditional fringe skeleton method will fail, whereas complete skeletons can be obtained through the trained network.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Simulation of mid-air images using combination of physically based rendering and image processing

    Koizumi, NaoyaHoshi, AyamiKiuchi, Shunji
    12页
    查看更多>>摘要：Although it is beneficial to use an optical simulator to design a mid-air imaging system, the use of a simulator requires optical knowledge, and it cannot be handled by non-specialists. To create a design assistance system that can be used by non-specialists, we demonstrate three methods: a method for extracting mid-air images and images of stray light from computer graphics rendered images, a method for calculating the visible range of mid-air images, and an evaluation of design parameters. First, a mid-air image and an image of stray light are extracted by considering the differences of images rendered using different numbers of bounces at each camera position, after which the visible range of the mid-air image is calculated. In addition, other parameters, such as the distance between a micro-mirror array plate (MMAP) and the extracted mid-air image, are adjusted in detail and evaluated by considering the visible range of the obtained mid-air image. Moreover, to demonstrate the effectiveness of the proposed method, the design of the previous research was improved to eliminate images of stray light, and we reduced the size of the existing system. Unlike other conventional approaches, using the visible range of the extracted mid-air images and without the need for a visual check, our proposed method enables the extraction of mid-air images and unwanted light, and the evaluation of optical systems. This technique can be applied to improve the design of optical systems and in the examination of the related applications.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Distributed feedback fiber laser-based broadband air acoustic sensor using PI film and PEEK shell structure

    Wang, Ying-YingWang, ChangZhao, Shi-WeiZhang, Fa-Xiang...
    8页
    查看更多>>摘要：The optical fiber air acoustic sensor has the advantages of anti-electromagnetic interference, intrinsic safety, and suitable for long-distance transmission. This paper proposes a non-metallic air acoustic sensor which is suitable for high-sensitivity concealed acoustic detection in environments such as electromagnetic interference. The sensor is based on a DFB fiber laser within an air cavity of polyimide (PI) film and poly-ether-ether-ketone (PEEK) shell. The dynamic acoustic response characteristics of the DFB fiber laser modulated by the acoustic-sensitive diaphragm is theoretically studied and numerically simulated. Based on the study and simulation results, a DFB fiber laser acoustic sensor for broadband detection covering the human auditory frequency range is designed and fabricated. An improved phase generated carrier (PGC) demodulation technique is introduced to realize high-resolution dynamic wavelength demodulation and, at the same time, to realize low sensitivity to modulation amplitude and photoelectric changes. The experimental test of the fiber laser air acoustic sensor demonstrated that, in the frequency range of 200 Hz to18 kHz, the sensitivity is - 40.39 dB re.pm/Pa, the fluctuation is less than +/- 3.15 dB, and the minimum-detectable pressure (MDP) is 66.7 mu Pa/root Hz at 1 kHz, and the lower limit of human hearing threshold is reached.
      原文链接:
    • NSTL
    • Optical Soc Japan

    The 12th International Conference on Optics-Photonics Design & Fabrication (ODF'20 in 2021), Taoyuan, Taiwan PREFACE

    Konno, Kenji
    1页
      原文链接:
    • NSTL
    • Optical Soc Japan

    Simulation on parameter optimization of gold nano-antenna attached to semiconductor ring resonator for heat-assisted magnetic recording device

    Sugiura, SatoshiChen, JinghanKatayama, Ryuichi
    13页
    查看更多>>摘要：Heat-assisted magnetic recording is a technology to improve recording density for hard disks. The authors' group has proposed a device, in which a gold nano-antenna as a near-field transducer is attached to a semiconductor ring resonator as an integrated light source. Localized surface plasmon resonance at the tip of nano-antenna excites near-field light to form small recorded marks to increase recording density. In this study, to improve the device performance, the dependence of spot size and energy density of near-field light on tip curvature, length, and bottom diameter of nano-antenna was investigated through a numerical simulation. Cylinder type and cone type nano-antennas were considered. For both types, as the tip curvature of nano-antenna increased, the spot size decreased and the energy density increased. It was possible to reduce the spot size to 18 x 18 nm(2). For cylinder type, there was an optimal length of nano-antenna where the energy density became maximum, and the optimal length changed depending on the presence or absence of recording medium. This was because of the difference in plasmon resonance condition. Moreover, for cone type, there was an optimal bottom diameter of nano-antenna where the energy density became maximum, and the optimal bottom diameter changed depending on the length of nano-antenna.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Multispectral image sensor attachable to low-cost microcomputers

    Ohtera, YasuoSato, AiriKawashima, TakayukiTakaya, Tomohisa...
    13页
    查看更多>>摘要：Multi-spectral filter array composed of a wavy alternating dielectric multilayer was integrated on a CMOS image sensor of the Raspberry Pi HQ Camera. The filter array consists of 16-channel elementary filters exhibiting pseudo-random transmission characteristics. Each filter covers 20 x 20 CMOS pixels. The incoming spectrum is encoded as a set of 16 grayscale intensities and passed to principal component analysis (PCA) to classify the states of the target spectral characteristic. Preliminary demonstration for blood flow state identification in human peripheral revealed proposed device's potential ability as a real-time monitoring tool in the near infrared.
      原文链接:
    • NSTL
    • Optical Soc Japan

    Improving resolution of lensless imaging with higher harmonics of Fresnel zone aperture

    Tajima, KazuyukiNakamura, YusukeYamaguchi, KeitaShimano, Takeshi...
    6页
    查看更多>>摘要：As part of our ongoing research on lensless imaging with a Fresnel zone aperture (FZA), we propose a method of improving resolution with higher FZA harmonics. Although previous research has required a finer FZA pitch to improve resolution, there was a limit to how much it could be utilized because of the diffraction. Our proposed method can improve resolution without a finer FZA pitch by utilizing higher harmonics. We confirmed the principle by simulation and experimentation.
      原文链接:
    • NSTL
    • Optical Soc Japan