Nanolayered Diamond Sintered Compact Obtained by Direct Conversion from Highly Oriented Graphite under High Pressure and High Temperature

A new type of polycrystalline sintered diamond has been successfully synthesized by direct conversion from highly oriented pyrolytic graphite at 15 GPa and 2300°C. It is optically transparent and consists entirely of layered nanocrystals (50–100 nm thick) of cubic diamond, which are tightly bound to each other and have strong [111] preferred orientation along the stacking direction. This nanolayered diamond has excellent indentation hardness (~114 GPa in Knoop scale) comparable to the highest values obtained from single crystalline diamond. Furthermore, it is expected to have significantly high wear resistance on both ends of cylindrical sintered compact, since the surfaces are terminated exclusively by the hardest {111} planes of the layered diamond nanocrystals

Survey and Analysis of College Students’ Copyright Awareness

大学の学部生を対象に著作権の意識調査をおこなった．著作物を扱う際に身近に起こりうる質問を設定し，全国400人の学生にWeb形式でアンケート調査を実施した．結果，学校や大学の授業でおこなう著作権教育には，知識習得に一定の効果が見られる一方，SNSなどでは著作権侵害行為をおこなってしまう傾向も見られた．また，著作権の知識にも勘違いが多い場合があることもわかった．大学ICT推進協議会 2022年度 年次大会 発表番号 : 13PM1B-1本研究はJSPS 科研費JP21H00896 の助成を受けたものである

Enhancing fluorescence excitation and collection from the nitrogen-vacancy center in diamond through a micro-concave mirror

We experimentally demonstrate a simple and robust optical fibers based method to achieve simultaneously efficient excitation and fluorescence collection from Nitrogen-Vacancy (NV) defects containing micro-crystalline diamond. We fabricate a suitable micro-concave (MC) mirror that focuses scattered excitation laser light into the diamond located at the focal point of the mirror. At the same instance, the mirror also couples the fluorescence light exiting out of the diamond crystal in the opposite direction of the optical fiber back into the optical fiber within its light acceptance cone. This part of fluorescence would have been otherwise lost from reaching the detector. Our proof-of-principle demonstration achieves a 25 times improvement in fluorescence collection compared to the case of not using any mirrors. The increase in light collection favors getting high signal-to-noise ratio (SNR) optically detected magnetic resonance (ODMR) signals hence offers a practical advantage in fiber-based NV quantum sensors. Additionally, we compacted the NV sensor system by replacing some bulky optical elements in the optical path with a 1x2 fiber optical coupler in our optical system. This reduces the complexity of the system and provides portability and robustness needed for applications like magnetic endoscopy and remote-magnetic sensing.Comment: 6 pages, 8 figure