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In mode-division multiplexing systems, the transmission quality is restricted by the differential mode delay (DMD). We previously proposed a spatial mode exchange technique using volume holograms (VHET) to reduce the DMD. VHET can be used for the exchange of multiple spatial modes with different transmission speeds using a single device. However, in VHET, incidents of cross-talk (XT) caused by non-target holograms severely degrade the exchange performance. To address this issue, we propose a spatial mode exchange technique that uses volume holograms in combination with a random optical diffuser. By scattering the intensity distribution of the signal beam uniformly using a random optical diffuser, high exchange performance can be attained due to the reduction in the influence of non-targeted holograms. We confirmed the basic operation of the proposed scheme by considering the crosstalk component coupled to the few-mode fiber in a mode-division multiplexing system. The simulation results show that the maximum XTs are significantly suppressed to − 15.8 dB.

Superhot geothermal environments in granitic crusts of approximately 400–500 °C are a frontier of geothermal energy. In the development of such environments, there is a concern of a reduction of permeability of fractured granite due to the formation of fine particles of amorphous silica induced by the phase change from subcritical water to supercritical water or superheated steam. However, the formation of silica particles and a resultant reduction in permeability have not been demonstrated to date. Therefore, experiments were conducted on the formation of amorphous silica particles with various combinations of temperature (430–500 °C) and pressure (20–30 MPa), in which the phase change of Si-containing water from liquid to either supercritical fluid or vapor was induced. Amorphous silica nanoparticles occurred under all conditions with smaller particles for higher temperature. The permeability of fractured granite was also observed to decrease significantly within several hours during injection of the particles into rock at 450 °C and 30 MPa under a confining stress of 40 MPa, with slower permeability reduction at a smaller number of particles or in the presence of larger aperture fractures. The present study suggests that the nanoparticles are likely to form and destroy the permeability in superhot geothermal environments, against which countermeasures should be investigated.

Security certification of quantum key distribution systems with a practical device is essential for their social deployment. Considering the transmitter, we investigate quantum state generation affected by degraded electrical signals from practical bandwidth-limited devices on high-speed phase-encoding BB84 quantum key distribution systems. The state preparation flaw caused by this degradation undesirably enhances the distinguishability between the two bases for the BB84 protocol and decreases the key generation rate. We propose the state preparation with a dual parallel modulator for increasing the robustness to signal degradation. To verify the effectiveness of the dual parallel modulator, we characterize the generated states using state tomography and estimate the key generation rate based on the Gottesman-Lo-Liitkenhaus-Preskill theory with fidelity derived from the estimated density matrices. Simulation results show that the key generation rate remains unaffected by modulation voltage shifts up to 20%. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

We propose a high-quality transparent visualization method suitable for large-scale laser-scanned point clouds. We call the method “stochastic point-based rendering (SPBR),” which is based on a novel stochastic algorithm. SPBR enables us to clearly observe the deep interior of laser-scanned 3D objects with the correct feeling of depth. The high quality of SPBR originates from the effect of “stochastic noise transparentization,” which is an effect to make the measurement noise transparent and invisible in the created images. We mathematically prove that this effect also makes the created transparent images coincide with the results of the conventional methods based on the alpha blending, which is time-consuming and impractical for large-scale laser-scanned point clouds. We also demonstrate the effectiveness of SPBR by applying it to modern buildings, cultural heritage objects, forests, and a factory. For all of the cases, the method works quite well, realizing clear and correct 3D see-through imaging of the laser-scanned objects.

To realize simplified cost-efficient optical networks with routing flexibility and scaling potential, a spatial-light-modulator-based optical-fiber joint switch for few-mode multicore fibers is proposed herein, which can route all spatial channels together as a unit. Numerical simulations and experiments were performed, and the results show that the signal paths for a 6-mode 19-core fiber can be simultaneously switched to the target output ports using the proposed method, and the mode-field patterns of the diffracted light can be maintained after joint switching. Further, the maximum port crosstalk can be reduced considerably from -11.6 to -25.1 dB by changing the position of the output port in the proposed method.

A wavefront superposition (WS) method is proposed for accurate and efficient mode conversion in mode-division multiplexing transmission. The WS method converts an input beam to the WS state, which is composed of the conversion target and radiation modes of a few-mode fiber. The appropriate weighting for the modal component of the WS state enables more efficient conversion than the conventional method in which the output beam consists only of the conversion target. Further, since the components of the radiation modes in the output are eliminated by the mode-filtering property of the few-mode fiber, no modal crosstalk occurs in the WS method. We examine the conversion performance of the WS method by a numerical simulation for the mode-multiplexing numbers 3, 6, 10, and 15. The WS method shows a 2.4 dB higher efficiency than the conventional method, while maintaining an extremely low modal crosstalk (less than -80 dB), even when the number of multiplexed modes is 15. (C) 2019 Optical Society of America

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2019-05-01, 資料番号: PA2010051000

Breast cancer is the most frequently found cancer in women and the one most often subjected to genetic analysis. Nonetheless, it has been causing the largest number of women's cancer-related deaths. PAM50, the intrinsic subtype assay for breast cancer, is beneficial for diagnosis and stratified treatment but does not explain each subtype's mechanism. Nowadays, deep learning can predict the subtypes from genetic information more accurately than conventional statistical methods. However, the previous studies did not directly use deep learning to examine which genes associate with the subtypes. Ours is the first study on a deep-learning approach to reveal the mechanisms embedded in the PAM50-classified subtypes. We developed an explainable deep learning model called a point-wise linear model, which uses a meta-learning approach to generate a custom-made logistic regression model for each sample. Logistic regression is familiar to physicians and medical informatics researchers, and we can use it to analyze which genes are important for subtype prediction. The custom-made logistic regression models generated by the point-wise linear model for each subtype used the specific genes selected in other subtypes compared to the conventional logistic regression model: the overlap ratio is less than twenty percent. And analyzing the point-wise linear model's inner state, we found that the point-wise linear model used genes relevant to the cell cycle-related pathways. The results of this study suggest the potential of our explainable deep learning to play a vital role in cancer treatment.

Accepted: 2021-06-23, PA2210008000

Mass transfer in rocks provides a direct record of fluid–rock interaction within the Earth, including metamorphism, metasomatism, and hydrothermal alteration. However, mass transfer analyses are usually limited to local reaction zones where the protoliths are evident in outcrops (1–100 m in scale), from which regional mass transfer can be only loosely constrained due to uncertainty in protolith compositions. In this study, we developed protolith reconstruction models (PRMs) for metabasalt based on a machine learning approach. We constructed PRMs through learning multi-element correlations among basalt compositional datasets, including mid-ocean ridge, ocean island, and island arc basalts. The PRMs were designed to estimate trace-element compositions from inputs of 2–9 selected trace elements, and basalt trace-element compositions (e.g., Rb, Ba, U, K, Pb, Sr, and rare earth elements) were estimated from only four inputs with a reproducibility of ~0.1 log10 units (i.e., ±25%). Using Th, Nb, Zr, and Ti, which are typically immobile during metamorphism, as input elements, the PRM was verified by applying it to seafloor altered basalt with known protoliths. When suitable immobile elements are incorporated, a PRM can yield unbiased and accurate mass transfer analysis of any metabasalt with unknown protolith.

Fluorine (F) implantation into gate poly-Si was used to incorporate F atoms in gate oxide films. Different F profiles in depth direction of gate oxide films were prepared. Enhanced segregation of F atoms at SiO2/Si interfaces was important for improvement of time dependent dielectric breakdown (TDDB) lifetime and suppression of hot carrier degradation. TDDB and low frequency noise dependences on gate length suggested that F profiles in lateral direction of gate oxide films should be cared for reliability of short channel devices.

Background The anesthetic management of cesarean sections in Fontan-palliated parturients requires strict hemodynamic control. However, patient management with central venous oxygen saturation (ScvO2) and oxygen consumption (VO2) has never been reported. Case presentation A 30-year-old woman, who had received a total cavopulmonary connection for tricuspid atresia, was planned to undergo cesarean section at 38 weeks’ gestation. During combined spinal-epidural anesthesia, ScvO2 in addition to arterial pressure-based cardiac output (APCO) and central venous pressure (CVP) was monitored, and the change of VO2 was evaluated. After delivery, her APCO was almost unchanged. However, her ScvO2 increased dramatically from 42.1 to 67.3% and her CVP increased from 9 to 11 mm Hg. The calculated mean maternal VO2 changed from 443 to 295 mL/min. Conclusions In a cesarean section for a Fontan-palliated parturient, ScvO2 dramatically increased and maternal VO2 decreased by more than 25% after delivery.

Steep retrograde doping devices were fabricated using undoped epitaxial Si channels with inserted oxygen layers. The effects of boron transient enhanced diffusion (TED) on threshold voltage (Vth) mismatch were investigated. Suppression of boron TED was effective for reducing V th mismatch of steep retrograde doping devices as well as flat doping profile devices.

To realize mode conversion with high accuracy and efficiency, we propose a new method based on dual-phase modulation (DPM) that utilizes the interference of two-phase-modulated beams. DPM realizes complex amplitude modulation with the interference of two-phase-modulated beams generated by phase-type spatial light modulators (PSLMs). DPM realizes highly efficient conversion using the interference of light rather than the diffraction that is conventionally used for complex amplitude modulation. Moreover, DPM enables the suppression of modal crosstalk (MXT) utilizing the destructive interference between two unwanted 0th beams that occur from PSLMs. In this paper, we experimentally confirmed that DPM can reduce the amount of the unwanted 0th beam. Then, we performed an experiment on mode conversion based on DPM and achieved a modal crosstalk of less than − 20 dB and an optical loss of less than 10 dB.

We experimentally implemented and proved the concept of multiplexing and demultiplexing in digital images using virtual phase conjugation, which was proposed in our previous study. In the experiment, we concluded that two digital images multiplexed in a single signal beam are recorded in a holographic medium, and these images are independently and successfully reproduced. In this method, the digital images are multiplexed by superimposing them on a complex amplitude, and not using volume hologram’s multiplexing. Thus, the exposure amount in the holographic medium is constant regardless of the number of multiplexing of digital images, and the method has great potential for achieving high recording density.

We propose a virtual phase conjugation (VPC) based optical tomography (VPC-OT) for realizing single-shot optical tomographic imaging systems. Using a computer-based numerical beam propagation, the VPC combines pre-modulation and post-demodulation of the probe beam's wavefront, which provides an optical sectioning capability for resolving the depth coordinates. In VPC-OT, the physical optical microscope system and VPC are coupled using digital holography. Therefore, in contrast to conventional optical tomographic imaging (OTI) systems, this method does not require additional elements such as low-coherence light sources or confocal pinholes. It is challenging to obtain single-shot three-dimensional (3D) tomographic images using a conventional OTI system; however, this can be achieved using VPC-OT, which employs both digital holography and computer based numerical beam propagation. In addition, taking into account that VPC-OT is based on a complex amplitude detection using digital holography, this method allows us to simultaneously obtain quantitative phase contrast images. Using an objective lens with a numerical aperture (NA) of 0.8, we demonstrate a single-shot 3D imaging of frog blood cells with a depth resolution of 0.94 mu m. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

著者人数: 35名, 形態: カラー図版あり, Number of authors: 35, Physical characteristics: Original contains color illustrations, Accepted: 2018-01-22, 資料番号: PA1810022000

Accepted: 2017-07-18, 資料番号: SA1170358000

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2017-11-05, 資料番号: PA1810073000

In the space division multiplexing system, differential mode delay (DMD) is an essential parameter for transmission quality and signal processing. In this paper, we proposed the collective measurement method for the DMD of each core in fewmode multi-core fiber (FM-MCF) using low-coherence digital holography (LCDH). In the conventional method, given that the DMD of each core needs to be measured individually, the number of measurements increases in proportion to the number of cores, which causes fluctuation of the measurement conditions. In contrast, the proposed method reduces the measurement time and realizes the accurate measurement under the same conditions for all cores. We experimentally demonstrate the proposed method by using 6-mode 19-core fiber as a fiber under test. As a result, DMD values were successfully measured for all 19 cores.

In this research, we propose a mode selective switch (MSS) using volume holograms. MSS is a device that distributes the mode-division multiplexed (MDM) signal to different output ports for each spatial mode component contained in the signal. Using MSS, the function of reconfigurable optical add / drop multiplexer (ROADM) can be implemented, which can manipulate arbitrary spatial mode signal at any position in the next generation MDM network. In our proposed MSS, the incident signal is separated into spatial mode components by the volume hologram on the input side. The signal destination will be selected for each mode by diffracting independently. The spatial mode components are separated in direction of the plurality of volume holograms on the output side using a spatial light modulator (SLM). In the volume hologram on the output side, the multiple spatial mode components are recombined and emitted once again as an MDM signal. This method has the advantageous that one volume hologram can multiplex or de-multiplex multiple modes, allowing it to cope easily with the increase in the number of modes and ports to be multiplexed. In the experiment, the optical signal lights of three-mode are separated for each spatial mode by the volume hologram on the input side, and the switching to either of the two ports on the output side is successfully performed for each mode using the SLM.

In mode-division multiplexing (MDM) systems, transmission quality is restricted by differential mode delay (DMD). We have proposed and developed a spatial-mode exchange technique using volume holograms (VHET) as a leading technology to reduce DMD. VHET can equilibrate the transmission time of each spatial mode which has different transmission speeds in a few mode fiber using a volume hologram. This technology enables low signal distortion and high spectral efficiency, which are indispensable to the long-haul transmission for the MDM system. However, in this technology, modal cross-talks (MXTs), which are caused by inter-page cross-talks in the volume hologram, seriously degrade the performance of VHET. In this study, we proposed a method of combining a volume hologram and a random optical diffuser to reduce the MXTs. In our method, the intensity distribution of the input spatial mode is diffused uniformly by a random optical diffuser. The high exchange performance will be attained because the non-targeted holograms included in the multiplexed holograms do not affect most of the spatial mode. Moreover, our method can be applied to the communication wavelength bands using the dual wavelength method. We confirmed the basic operation of the proposed scheme using a linearly polarized mode group comprising LP0,1, LP1,1, and LP2,1. Compared with the conventional VHET, the simulation results show that the maximum MXTs are significantly suppressed from 0.4 to -15.8 dB.

Summary Faults and fractures are important fluid pathways in subsurface energy reservoirs. Especially in geothermal energy production, hydrocarbon production, and energy storage in the deep subsurface, fractures can enhance reservoir quality and production- or storage potential. In subsurface reservoirs however, mineral precipitations often reduce available fracture apertures, and thus fracture porosity and permeability. The present study is performed on a homogeneous, massive marine Sandstone (Bentheimer Sandstone from Gildehaus Quarry, Lower Saxony, Germany, Lower Cretaceous) and a heterogeneous, laminated fluvial sandstones (gres vosgien from Cleebourg, Alsace, France, Lower Triassic). Hydrothermal flow-through experiments are performed at 420 °C and 30 MPa for 72 hours to compare resulting precipitated cement textures on fracture analog surfaces. The experiments reveal a heterogeneous development of syntaxial overgrowth cements. Homogeneous sandstone, composed of similar grain sizes and quartz grains, show a homogeneous formation of overgrowths. Heterogeneous sandstones, composed of laminae with different grain sizes and variable detrital grain compositions, show smaller overgrowths on finer grained laminae when compared to coarser grained laminae. The sedimentary texture might thus be an additional factor to consider when assessing mineral precipitations in fractures and their influence on subsurface fluid flow.

The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to the 2016 Hitomi mission that ended prematurely. Like Hitomi, the primary science goals are to examine astrophysical problems with precise highresolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. XRISM carries a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly and a co-aligned X-ray CCD camera that covers the same energy band over a large field of view. XRISM utilizes Hitomi heritage, but all designs were reviewed. The attitude and orbit control system were improved in hardware and software. The number of star sensors were increased from two to three to improve coverage and robustness in onboard attitude determination and to obtain a wider field of view sun sensor. The fault detection, isolation, and reconfiguration (FDIR) system was carefully examined and reconfigured. Together with a planned increase of ground support stations, the survivability of the spacecraft is significantly improved.

For mode-division multiplex transmission, a volume holographic mode (de-) multiplexer with dual-wavelength method has been proposed. We experimentally achieved the 13 times power efficiency by considering the condition of hologram recording.

As part of leading research for future space missions, we have been conducting a feasibility study on an optical imager system assumed to be mounted on a geostationary satellite for instantaneous Earth observation as needed. The target for ground sampling resolution was less than 10 m from geostationary orbit, and the primary mirror was set to a diameter of 3.5 m based on our previous conceptual study. Moreover, the primary mirror was conceptually designed with cuttingedge technologies such as segmented mirror technology for scalability to larger sizes in the future. The main technical challenges in achieving such a large optical system entailed reducing the primary mirror weight and minimizing dimensional changes in the space environment. Optical material selection was a particularly key consideration in defining the optical system performance. Therefore, a trade-off study was conducted on the selection of materials for the segmented primary mirror. The thermal deformation behaviors of certain low thermal expansion materials as mirror substrates were analytically compared under the assumed unsteady and inhomogeneous thermal conditions in geostationary orbit, in consideration of the deterioration induced by radiation.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm constituting approximately 15% of newly diagnosed leukemia in adult patients. Development of tyrosine kinase inhibitors (TKIs) have dramatically improved outcomes in patients with chronic CML in chronic phase. However, adverse drug events (ADEs) associated with TKI therapy have influenced drug adherence, resulting in adverse clinical outcomes and a decline in the quality of life (QoL). In this study, we carried out a unique questionnaire survey to evaluate ADEs, which comprised 14 adverse events. We compared drug adherence rates between patients using imatinib and those who switched from imatinib to nilotinib, a second-generation TKI. Following the switch, the total number of ADEs decreased considerably in most cases. Simultaneously, better QoL was observed in the nilotinib group than in the imatinib group. Drug adherence was measured using Morisky’s 9-item Medication Adherence Scale (MMAS). MMAS increased significantly after switching to nilotinib in all cases. Drug adherence is a critical factor for achieving molecular response in patients with CML. In fact, our results showed a strong inverse correlation between clinical outcome [international scale (IS)] and adherence (MMAS), with a stronger tendency in the nilotinib group than in the imatinib group. In conclusion, low occurrence of ADEs induced a high level of QoL and a good clinical response with second-generation TKI nilotinib treatment.

Highly accurate mode conversion was realized by iterative spatial cross modulation. Modal crosstalk was realized less than −29.9 dB for all conversion targets in the case of coupling to a six-mode fiber.

We propose a mode selective switch (MSS) using volume holograms and a spatial light modulator to constitute the core of an MDM network. We clarify the characteristics of the MSS for two different spatial modes.

We fabricate and characterize a spatial-mode demultiplexer using 1550-nm-band, 5-mode angularly multiplexed volume holograms. It is confirmed that a degradation of diffraction efficiencies by increasing the number of recorded modes are small.

The hypothesis that the brittle–ductile transition (BDT) drastically reduces permeability implies that potentially exploitable geothermal resources (permeability >10−16 m2) consisting of supercritical water could occur only in rocks with unusually high transition temperatures such as basalt. However, tensile fracturing is possible even in ductile rocks, and some permeability–depth relations proposed for the continental crust show no drastic permeability reduction at the BDT. Here we present experimental results suggesting that the BDT is not the first-order control on rock permeability, and that potentially exploitable resources may occur in rocks with much lower BDT temperatures, such as the granitic rocks that comprise the bulk of the continental crust. We find that permeability behaviour for fractured granite samples at 350–500 °C under effective confining stress is characterized by a transition from a weakly stress-dependent and reversible behaviour to a strongly stress-dependent and irreversible behaviour at a specific, temperature-dependent effective confining stress level. This transition is induced by onset of plastic normal deformation of the fracture surface (elastic–plastic transition) and, importantly, causes no ‘jump’ in the permeability. Empirical equations for this permeability behaviour suggest that potentially exploitable resources exceeding 450 °C may form at depths of 2–6 km even in the nominally ductile crust. The brittle–ductile transition is thought to control crustal permeability. Laboratory experiments and model simulations show that permeability is also stress dependent and ductile granitic rocks may have enough permeability to host geothermal resources.

Persistent homology is a mathematical method to quantify topological features of shapes, such as connectivity. This study applied persistent homology to analyze fracture network patterns in rocks. We show that persistent homology can detect paths connecting from one boundary to the other boundary constituting fractures, which is useful for understanding relationships between fracture patterns and flow phenomena. In addition, complex fracture network patterns so-called mesh textures in serpentine were analyzed by persistent homology. In previous studies, fracture network patterns for different flow conditions were generated by a hydraulic–chemical–mechanical simulation and classified based on additional data and on expert's experience and knowledge. In this study, image analysis based on persistent homology alone was able to characterize fracture patterns. Similarities and differences of fracture network patterns between natural serpentinite and simulation were quantified and discussed. The data-driven approach combining with the persistent homology analysis helps to infer fracture forming processes in rocks. The results of persistent homology analysis provide critical topological information that cannot be obtained by geometric analysis of image data only.

The activity of saving and utilizing cultual heritage items as digital data by three-dimensional (3D) measurement is called digital archive. Digital archiving requires visualization that is accurate and easy for the observer to understand the structure. Therefore, visualization combining see-through visualization and stereoscopic presentation is considered effective. In previous studies, it has been reported that the depth is perceptually underestimated in see-through stereoscopic vision of 3D point clouds. In this research, in order to solve the problem, we propose an edge highlighting method for the 3D structure of data and show its effectiveness by an evaluation experiment. Moreover, in this research, new depth information is added by applying the method of dashed lines to the extracted edge. We conduct another evaluation experiment and show that these dashed lines have influences on perceived depth.

Superhot geothermal environments in granitic crusts of ca. 400–500 °C and depths of 2–4 km are recognized as a frontier of geothermal energy. In developing such environments, hydraulic fracturing is a promising way to create or recreate permeable fracture networks to effectively access the energy through enhanced geothermal systems (EGS). However, there is a concern about the possibility of stabilizing or enhancing the permeability created by hydraulic fracturing, required for sustainable and profitable energy production, because pressure solution of the fracture surfaces may reduce permeability. On the other hand, permeability may be enhanced by free-face dissolution of the fracture surfaces even if pressure solution occurs. However, the rates of permeability reduction and enhancement are not fully understood, and the possibility of stabilizing/enhancing permeability is therefore unclear. We have conducted hydrothermal flow-through experiments on 400 °C fractured granite samples to clarify the influences of stress level and plasticity of the fracture on the rate of permeability reduction by pressure solution and the influences of pore water pressure and corresponding mineral solubility on the rate of permeability enhancement by free-face dissolution. Results suggest that permeability may be either stabilized or enhanced in superhot EGS even when pressure solution can occur by keeping the difference between the concentration of the pore water and the solubility of quartz higher than the stress-dependent permeability stabilization criterion.

A volume-holographic spatial-mode demultiplexer for the 1550-nm band is created and described, for the first time. Angularly multiplexed volume holograms combined with a dual-wavelength method achieve three-mode demultiplexing with a crosstalk of less than −20 dB.

The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi,“Resolving astrophysical problems by precise high-resolution X-ray spectroscopy”.1 This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission’s initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020’s and 2030’s. Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: “Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects”. To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 × 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.

著者人数: 270名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 高橋, 忠幸; 国分, 紀秀; 満田, 和久; Baluta, Chris; 坂東, 信尚; 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 廣瀬, 和之; 飯塚, 亮; 石田, 学; 石川, 久美; 石村, 康生; 岩井, 将親; 岩田, 直子; 河野, 太郎; 川崎, 繁男; 小山, 志勇; 前田, 良知; 峯杉, 賢治; 中川, 貴雄; 夏苅, 権; 小川, 博之; 小川, 美奈; 太田, 方之; 岡崎, 健; 尾崎, 正伸; 坂井, 真一郎; 鮫島, 寛明; 佐藤, 悟郎; 佐藤, 理江; 柴野, 靖子; 志田, 真樹; 嶋田, 貴信; Simionescu, Aurora; 菅原, 泰晴; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 田代, 信; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 上野, 史郎; 和田, 篤始; 渡辺, 伸; 山田, 隆弘; 山崎, 典子）, Number of authors: 270 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Takahashi, Tadayuki; Kokubun, Motohide; Mitsuda, Kazuhisa; Baluta, Chris; Bando, Nobutaka; Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Hirose, Kazuyuki; Iizuka, Ryo; Ishida, Manabu; Ishikawa, Kumi; Ishimura, Kosei; Iwai, Masachika; Iwata, Naoko; Kawano, Taro; Kawasaki, Shigeo; Koyama, Shu; Maeda, Yoshitomo; Minesugi, Kenji; Nakagawa, Takao; Natsukari, Chikara; Ogawa, Hiroyuki; Ogawa, Mina; Ohta, Masayuki; Okazaki, Tsuyoshi; Ozaki, Masanobu; Sakai, Shinichiro; Sameshima, Hiroaki; Sato, Goro; Sato, Rie; Shibano, Yasuko; Shida, Maki; Shimada, Takanobu; Simionescu, Aurora; Sugawara, Yasuharu; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tashiro, Makoto; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Ueno, Shiro; Wada, Atsushi; Watanabe, Shin; Yamada, Takahiro; Yamasaki, Noriko Y.), Accepted: 2018-02-05, 資料番号: SA1170333000

In the mode division multiplexing (MDM) system, differential mode delay (DMD) restricts the quality of transmission. Thus, it is necessary to precisely measure DMD for compensation and system design. The DMD measurement method using low-coherence digital holography (LCDH) has been proposed. This method can obtain not only accurate DMD but also spatial mode fields. However, in this method, an SMF as the reference arm is needed and its length should be particularly adjusted to a fiber under test (FUT) for low-coherence interferometric measurement. We propose a DMD measurement method by reference-free low-coherence digital holography (RF-LCDH). In the proposed method, we generate a new optical path from the light emitted from the FUT, which is regard as internal-reference light. The proposed method enables us to obtain DMD and spatial mode fields without the SMF as the reference arm by using internal-reference light. In the experiment, we measured DMD of a 10-mode fiber to confirm the basic operation of the proposed method. As the result, without using additional SMFs for reference arm, the proposed method achieved the measurement accuracy which was in good agreement with that of the conventional method.

In a mode division multiplexing (MDM) transmission using few-mode fibers (FMFs), differential modal gain (DMG) in amplifiers and mode dependent loss (MDL) cause deterioration in signal quality. Therefore, the techniques which selectively attenuate multiplexed modes and equalize optical powers among mode channels are required for a long-haul MDM transmission. In this paper, we propose a selective mode attenuator using phase-intensity-phase (PIP) modulation. The PIP modulation, consisting of a cascade of two phase and one intensity modulation masks connected by optical Fourier transforms (OFTs), makes it possible to selectively attenuate multiplexed mode channels with high accuracy. In the proposed method, the intensity distributions of spatial modes are converted by the phase modulation and OFT, before doing attenuation by intensity mask located between the two phase masks. Due to the action of a pair of phase masks having phase conjugate relations, accurately selective mode attenuation can be performed even if the number of modes is increased over three. To confirm the basic operation of the proposed method, we perform a numerical simulation for power equalization among six spatial modes (LP01, LP11a, LP11b, LP21a, LP21b, and LP02) having different powers. The phase and intensity masks are designed by using simulated annealing. Moreover, we also evaluate modal crosstalk (MXT) characteristics and the wavelength dependence of the equalization in C-band. The results show that the optical powers of all modes are successfully equalized for any wavelengths and the MXT smaller than −25 dB were achieved between all modes.

Volume holographic demultiplexers (VHDMs) provide spatial mode demultiplexing using simple optical systems. However, applying VHDM to practical optical communication systems is difficult, as typical holographic media have no sensitivity in the infrared region, which includes optical transmission bands. In this paper, we propose a VHDM scheme combined with a dual-wavelength method (DWM). Using the DWM, VHDMs are able to perform mode demultiplexing in the optical transmission bands. We experimentally demonstrated the basic operation of our proposal using experiments performed at an 850-nm wavelength. In addition, we performed numerical simulations to investigate the application of VHDM to the C-band.

In recent years, with the development of 3D laser-measurement technology, digital archiving is being carried out as one of the efforts to leave cultural assets to posterity around the world. The laser-scanned point clouds are large-scale and precisely record complex 3D structures of the cultural assets. Accordingly, such point clouds are used in research field of visualization to support analysis and use of the assets. As representative examples of visualization, there are feature-highlighting and transparent visualization. The quality of visualization highly depends on distributional uniformity, that is, uniformity of inter-point distances. However, laser-scanned point clouds are usually distributional bias data, which makes it impossible to visualize with high quality. In previous studies, making point distances uniform by Poisson disk sampling, the quality of transparent visualization can be improved. This study proposes curvature-dependent Poisson disk sampling. The proposed method adjusts the order and radius of the sampling disk according to the curvature calculated by principal component analysis. By applying the proposed method to laser-scanned point clouds, the edges of cultural assets can be emphasized and the visibility of shape further improves in transparent visualization. Thereby, we realize feature-highlighting transparent visualization with high visibility of three-dimensional structure and edge-shape.

A hybrid real-time simulator is proposed in order to evaluate the applicability of various customers' equipment to direct load control (DLC). The real-time simulator (H- DLCSim) is composed of a PC, actual equipment and interfaces between the PC and the equipment. In the PC, a power system model and load controllers are installed as software. The actual equipment is the candidate of controllable load to be studied for DLC. In our study, two types of geothermal heat pump air conditioners (GeoHPs) were chosen as the candidates. An H-DLCSim for DLC assisting load frequency control (LFC) was developed and a case study showed its usefulness.

We propose a selective mode conversion method using dual-phase modulation which performs the full-complex amplitude modulation by use of two phase-type spatial light modulators. In the experiment, the crosstalk to undesired spatial mode was supressed less than −21.2 dB for the 4-LP modes of a few-mode fiber.