比田井 洋史

The ring-core refractive-index profile in RO-Al2O3-SiO2 glass (R = Ca and Ba) was formed by the manipulation of a platinum (Pt) microsphere via continuous-wave laser irradiation method (the CW-LM3 method). The homogeneously modified area could be obtained in the CAS glass (R = Ca) with a wide velocity of the microsphere, though the BAS glass (R = Ba) showed inhomogeneous modified area with periodic structure. The even-width modified line was fabricated by controlling the velocity of the Pt microsphere, and the ring-core structure with the highest refractive index change was fabricated in the CAS glass with the Pt-microsphere speed of 46 mu m/sec.

We have reported that laser-induced metal particle migration in glass. Laser illumination heated a metal particle in glass. The surrounding glass of the metal particle was also heated and softened hence, the metal particle migrated in the glass. The temperature gradient caused the driving force. The interfacial tension between the glass and the metal particle was varied by the temperature. The temperature nonuniformity caused the interfacial tension nonuniformity and metal particle migration. In this presentation, we demonstrated metal particle migration by the surface heating of the glass with a CO2 laser. Heating of glass surface moved metal particle located 200 μm below the surface. The particle was moved out of the glass after 400 s illumination. The migration speed was 0.30.7 μm/s.

Wheel scribing techniques were commonly used for glass separation. We have studied on the internal stress field during/after wheel scribing using the photoelastic method. Internal stress data obtained by photoelastic method was integrated data of the light progression, and internal stress induced by a scribing wheel distributed three-dimensionally. This characteristic complicates the explanation of the photoelastic data. In this paper, we investigate two dimensional internal stress fields by the indentation of a wedge on a thin glass sheet. As a result, birefringence and azimuthal angle was obtained during/after the indentation. Internal stress by the plastic deformation was observed. First, median cracks were propagated after the indentation, then lateral cracks were propagated. The internal stress was released along with the crack propagation.

<p>Turning with suppressing thrust force has been proposed as a method of processing a micro-shaft. Advantages of thrust force free cutting have been demonstrated by turning micro-shaft (diameter: ~0.05 mm). Although the feed rate is a small value in the previous research, the processing efficiency has not been discussed because the processed shaft is small. If the long shaft is machined, it is indispensable to increase the feed rate to improve the machining efficiency. Therefore, in this research, we confirmed whether the suppression of thrust force was possible with high feed rate to expand the application range of thrust force suppression turning. The condition of suppressing thrust force by turning the long shaft of the medium diameter (~1 mm) was chosen, and the range of the small deformation by suppressing thrust force was clarified. It was also found that deflection due to principal cutting force also caused dimensional error even when thrust force was suppressed.</p>

There have been many investigations into the changes in the properties of transparent materials, e.g. optical, physical and chemical properties, induced by focused ultrafast laser beams. In this letter, we report the modification of borosilicate glass using an ultraviolet nanosecond laser. A laser beam operating at a wavelength of 266 nm was focused inside the glass. Interestingly, although penetration depth of the laser beam was only 110 μm, emission was observed in the glass at the depth of approximately 1100 μm after several laser shots. The emission moved toward the light source with further laser illumination, and modification of the glass along the trajectory of the emission was observed. The modified area became deeper with increasing focusing depth. The deepest modified area was located at a depth of approximately 1800 μm. No clear dependence of the modification on the pulse repetition rate was found; therefore, heat accumulation was not prominent in the modification process. The subsequent etching rate of the modified area was faster than that of the unmodified area. The etching rate in aqueous KOH was 60 μm/h where continuous modification was obtained. A microchannel with a depth of approximately 400 μm and a diameter of approximately 30 μm was formed after 10 h etching.

レーザ割断加工では，加工中の温度や応力状態を予測し，ガラスに熱的ダメージを与えない最適な割断条件を決定する必要がある．本研究では，レーザ割断の機構として構築した三次元温度場モデル，二次元熱弾性モデルと，偏光高速度カメラによる位相差計測の両面から，割断中の動的変形挙動について調べた．解析と実験で得られた位相差分布はよく類似しており，レーザ通過後に発生した引張応力域で亀裂が進展していることを確認した．

CWレーザ背面照射法(CW-LBI)を利用して，ガラスの表面に密着させた金属箔に対しガラス越しにレーザ照射し金属微粒子を導入した．導入した微粒子の移動に寄与する物性値の温度依存性を考慮し，熱流体解析の結果から移動速度の評価を行った．また，粒子画像流速測定法を用いてガラスの速度場の可視化を行い解析結果と比較を行った．以上の結果から移動メカニズムの妥当性を検討した．

<p>Using electric-field-assisted solid-state ion exchange, metal ions were doped into borosilicate glass surface. When a silver foil was used as a dopant, a buried silver layer was formed in glass substrate by additional voltage application with opposite direction to the case of doping (referred to as reverse voltage). Because the formed layer was electrically conductive, we tried to create a buried silver electric circuit in glass substrate. Especially for the multi-layer formation, silver and sodium were alternatively doped to glass surface. As a result, the three-layered structure consisted of sodium- or silver-rich layers was successfully formed in a glass substrate. By the reverse voltage application, a silver precipitation layer connecting between silver-rich layers in double- and three-layered structures was formed.</p>

Optical vortex illumination enables the creation of silicon needles with a height of similar to 14 mu m and a thickness of similar to 2 mu m. Silicon needle formation requires an optical vortex pulse with a pulse duration of 10 similar to 20 ps, so as to create thermally-melted silicon with fewer heat diffusion effects.

The crack propagation behavior and the internal stress field during mechanical cleavage of non-alkali glass sheets (thickness : 0.7mm) were visualized by high-speed imaging techniques. At first, the effect of scribing conditions on the fractured surface quality was investigated when the scribing wheel with surface asperities was used. It was found that the surface quality was strongly influenced by an applied load. In the case of low load conditions (∼11N), the fractured surface exhibited rugged patterns known as 'hackle', and it gradually changed to regular striped pattern known as 'ribmark' with the increase of applied load (12N∼). In order to understand the reason why the surface quality changed with the applied load, the crack propagation behavior was observed using a high-speed camera. The results showed that the generated crack hardly propagated to thickness direction when the applied load was low, in contrast to the rapid propagation under the high load conditions. Because the crack propagation behavior was likely determined by the stress field around the generated crack, the phase difference measurement, which was proportional to the principal stress difference, was conducted using a high-speed polarization camera. The results showed that the phase difference gradually vanished, i.e. the stress relaxation occurred, with the crack propagation especially in the high load conditions. By the image analysis for obtained phase difference from the polarization camera, an in-process estimation method of fractured surface quality was proposed.

結合部の真実接触面積を超音波で測定する場合，結合面の変形が弾性変形領域の場合と塑性変形領域の場合とでは測定結果が変化することが先行研究で確認されている．そこで本報では，塑性変形によって発生する点欠陥の影響をふまえて考察した．塑性変形により点欠陥が発生すると，超音波縦波伝搬速度が変化する．すると，見かけの音響インピーダンスが変化し，結合部での反射率が増加するため，測定結果が異なる．

本研究では，スクライビングホイールを用いた薄板ガラスのホイール割断時のホイールの押し付け荷重，走査速度が亀裂の進展挙動及び断面品質に及ぼす影響を調査した．また，偏光高速度カメラを用いてホイール割断時のガラス内部の位相差を計測した．得られた結果を用いて位相差と亀裂の進展挙動の関連性の解明を試みた．また，位相差を用いてスクライブ時のガラスの断面品質をリアルタイムで推定する方法を検討した．

旋削加工において，負のアプローチ角を採用すると，切込み量の増加につれて背分力が小さくなる．これを利用して背分力を抑制し，高精度な微細軸を加工する方法が提案されている．本研究では，背分力抑制による形状精度の向上の可能性を検討した．汎用旋盤を用いて，送り量等を変更して旋削を行い，切削抵抗を測定した．それにより，送り量がある範囲の場合において背分力が抑制できることを示した．

近年，ガラスの切断方法としてレーザによる熱応力割断が用いられている．レーザ割断中の温度や応力状態を予測し，ガラスに熱的ダメージを与えない最適な割断条件を決定する必要がある．本研究では，レーザ割断の機構として三次元温度場モデルと二次元熱弾性モデルを構築し，レーザ照射位置と水冷位置との距離が割断に与える影響を調べた．水冷距離によって引張応力が変化し，引張応力が極大になる水冷距離が存在する可能性がある．

ガラス内部への金属微粒子の導入方法としてCWレーザ背面照射法を提案している．これはガラス越しの金属箔にレーザを照射することで微粒子を導入する手法だが，箔の熱伝導により伝導率の低い金属しか導入できていない．本発表では箔の代わりにガラス内に予め粉末を入れることでより多くの金属の導入可能性を検討し，金属粉末を含有したガラスの作製を行った．その結果Ni微粒子含有ガラスを作製し，レーザ照射による移動を確認した．

ガラス基板上の電子デバイスを気密封止するレーザ接合において低融点ガラスとガラス基板のそれぞれの温度履歴の把握が必要である．低融点ガラスは2枚のガラス基板に挟まれたサンドイッチ構造である．サンドイッチ構造の熱影響を予測するために非定常二次元温度モデルを提案した．レーザ接合実験と同じ条件下でサンドイッチ構造の温度変化を温度モデルから予測した．最適な接合条件における熱影響を調査した．

本研究では順・逆電圧印加を併用したイオン交換法によりガラス中に金属層を形成した．逆電圧印加時間を変化させた実験の結果，逆電圧印加直後に表面近傍のガラス内部に析出物が生成され電圧印加時間の増加と共に析出物が成長することがわかった．成長した析出物は金属添加領域と未添加領域の境界に到達した後，境界に沿う形で成長することにより添加領域の最深部に層を形成していることが分かった．

現在,摩擦撹拌接合(FSW)および摩擦スポット接合(FSJ)は大型構造物などの接合に適用が広がっている.しかし,マイクロサイズでの接合となると研究例が少なく,接合条件など不明な部分が多い.本研究ではマイクロサイズの接合を可能とする卓上FSJ装置を設計・製作し,0.1～0.3mm厚の純Al薄板を2枚重ね合わせてFSJを行った.また接合部断面の観察も行い,接合条件および接合状態の評価,検討を行った.

剛性の低い被削材を旋削加工する場合，背分力は寸法精度を悪化させる．そのため，背分力の抑制により寸法精度を向上させる方法が提案されている．本研究では特に送り量が微小な場合について，背分力がゼロとなる加工条件を理論的に求めることを目的とする．微小送りにおける加工現象では工具切れ刃稜丸みの影響が大きい．そこで，切れ刃周辺の被削材挙動をモデル化し，計算に反映することで切削抵抗予測式の高精度化を検討した．

In this study, we propose the new equations which predict cutting forces under the conditions of a small feed (2.5μm) and negative approach angle. They are based on Nakayama's equations. According to our previous research, the experimental cutting forces were larger than the calculated forces with Nakayama's equations. The differences were caused by size effect. One of the causes of size effect was a cutting edge radius. Therefore, the new equations were formulated with taking into account the cutting edge radius. The cutting force calculated by the new equations were approximately equal to the experimental results. The accuracy of the new equations is validated under the conditions of thrust force free cutting.

We for the first time demonstrated a chiral mono-crystalline cone-shaped silicon structure (chiral Si nano-cone). It was fabricated on a nano-scale by transferring the optical angular momentum of optical vortex to a mono-crystalline Si substrate. © 2014 OSA.

We for the first time demonstrated a chiral mono-crystalline cone-shaped silicon structure (chiral Si nano-cone). It was fabricated on a nano-scale by transferring the optical angular momentum of optical vortex to a mono-crystalline Si substrate.

Metal (silver or copper) ions were doped into borosilicate glass using an electric field- assisted ion exchange method. The optical transmittance of the metal doped glass was measured to determine why the doped glass exhibited an excellent laser micro-machinability. The doped metal ions were found to have enhanced the optical absorption of the glass, especially in the ultraviolet range. This in turn facilitated the efficient absorption of incident laser irradiation, and hence improved laser machinability of the glass. The metal doped glass also exhibited some absorption in the visible range, leading to a slight yellow-brown coloration. Transmission electron microscope (TEM) observations indicated that the metal ions had penetrated the glass and therein formed nanometer-sized (∼6 nm) fine particles. In an attempt to control the optical characteristics in the ultraviolet-visible range, metal doped glass was heat-treated following the ion exchange doping step. In the case of silver-doped glass with heat treatment at 723 K, silver nanoparticles aggregated locally yielding an inhomogeneous structure. The heat-treated samples had a high optical absorption in the ultraviolet range.