Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (research society, symposium materials, etc.)  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1088/1555-6611/ace886

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.infrared.2023.104686

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

DOI： 10.1016/j.infrared.2023.104620

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

DOI： 10.1016/j.optlastec.2022.108174

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer  

DOI： 10.1007/s40516-022-00165-7

Other Link： https://link.springer.com/article/10.1007/s40516-022-00165-7

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

DOI： 10.1016/j.optlastec.2021.107745

Language：English   Publishing type：(MISC) Introduction and explanation (scientific journal)   Publisher：Springer Nature  

DOI： 10.1007/978-3-319-69537-2

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2573908

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2573974

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OAText  

DOI： 10.15761/DOMR.1000355

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Laser Processing Society  

DOI： 10.2961/jlmn.2019.02.0012

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2507718

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：(MISC) Prompt report, short report, and research note, etc. (bulletin of university, research institution)   Publisher：天田財団  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2500559

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP Publishing  

Simple, compact, and affordable discharged-pumped CO2 laser controlled by a fast high voltage solid state switch has been developed. In this study, longitudinal excitation scheme has been adapted for simple configuration. In the longitudinal excitation scheme, the discharge is produced along the direction of the laser axis, and the electrodes are well separated with a small discharge cross-section. Triggered spark gap switch is usually used to switch out the high voltage because of simple and low cost. However, the triggered spark gap operates in the arc mode and suffer from recovery problem causing a short life time and low efficiency for high repetition rate operation. As a result, there is now considerable interest in replacing triggered spark gap switch with solid state switches. Solid state switches have significant advantages compared to triggered spark gap switch which include longer service lifetime, low cost and stable high trigger pulse. We have developed simple and low cost fast high voltage solid state switch that consists of series connected-MOSFETs. It has been installed to the longitudinally excited CO2 laser to realize the gap switch less operation. Characteristics of laser oscillation by varying the discharge length, charging voltage, capacitance and gas pressure have been evaluated. Longer discharge length produce high power of laser oscillation. Optimum charging voltage and gas pressure were existed for longitudinally excited CO2 laser.

DOI： 10.1088/1742-6596/1027/1/012010

Scopus

Language：Japanese   Publishing type：Research paper (research society, symposium materials, etc.)   Publisher：レーザー学会  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (research society, symposium materials, etc.)   Publisher：レーザー学会  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

We developed a longitudinally excited CO2 laser with a tail-free short pulse and a high quality beam. The laser system had a longitudinal discharge tube, a long optical cavity and a simple driver circuit. The discharge tube was made of an alumina ceramic pipe with an inner diameter of 16 mm and a length of 45 cm, two metallic electrodes and two windows. Gas medium was a 20:1 mixture of CO2/N2at a pressure of 2.6 kPa. The optical cavity with the length of 180 cm was formed by an output coupler with a reflectivity of 70% and a high-reflection mirror. The optical cavity had an aperture or did not. The driver circuit consisted of-600 V pulse power supply and a primary capacitance of 9.6 μF, a step-up transformer, a storage capacitance of 700 pF, a spark gap and the discharge tube. The CO2 laser produced a tail-free short pulse with the width of 281 ns. The CO2 laser beam was a ununifomly distributed circular beam with the M2 factor of 22.8 in the laser system without an aperture, a top-hat shape of circular beam with the M2 factor of 9.61 in the laser system with a φ11-mm aperture, 5.40 in the laser system with a φ9-mm aperture, or a Gaussian shape of circular beam with the M2 factor of 3.01 in the laser system with a φ7-mm aperture.

DOI： 10.1117/12.2288071

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

We developed a longitudinally excited N2 laser with a simple driver circuit and a simple power supply. The N2 laser consisted of a 20 cm-long glass tube with an inner diameter of 2.5 mm, a normal stable resonator formed by flat mirrors, a variable transformer, a neon sign transformer, a spark gap, and a 200 pF capacitance. The N2 laser produced a laser pulse with an energy of 379 nJ and a pulse width of 7.5 ns at a repetition rate of 100 Hz. The laser beam was circular and had a Gaussian profile with a correlation factor of 0.992 93.

DOI： 10.1063/1.5009179

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

In a longitudinally excited CO2 laser that had a 45 cm-long discharge tube with a 1:1:2 mixture of CO2/N2/He gas at a pressure of 3.0 kPa, we realized the generation of a short laser pulse with a spike pulse width of about 200 ns and a pulse tail length of several tens of microseconds, control of the energy ratio of the spike pulse part to the pulse tail part in the short laser pulse, the generation of a long laser pulse with a pulse width of several tens of microseconds, and control of the pulse width in the long laser pulse, by using four types of excitation circuits in which the capacitance was adjusted. In the short laser pulse, the energy ratio was in the range 1:14–1:112. In the long laser pulse, the pulse width was in the range 25.7–82.7 μs.

DOI： 10.1016/j.optlastec.2017.11.020

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-OSA  

We developed a longitudinally excited CO2 laser with a long optical cavity and investigated the drilling characteristics of dental hard tissue. The CO2 laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 13 mm, a pulse power supply, a step-up transformer, a storage capacitance, a spark gap, and a long optical cavity with a cavity length of 175 cm. The CO2 laser produced a short pulse that had a spike pulse with the width of 337 ns and the energy of 1.9 mJ, a pulse tail with the length of 180 μs and the energy of 37.6 mJ, and a doughnut-like beam. In the investigation, a sample was a natural drying human tooth (enamel and dentine). In a processing system, a ZnSe focusing lens with the focal length of 50 mm was used and the location of the focal plane was that of the sample surface. In 1 pulse irradiation, the drilling characteristics depended on the fluence was investigated. In the enamel and dentin drilling, the drilling depth increased with the fluence. The 1 pulse irradiation with the fluence of 21.5 J/cm2 produced the depth of 79.3 μm in the enamel drilling, and the depth of 152.7 μm in the dentin drilling. The short-pulse CO2 laser produced a deeper drilling depth at a lower fluence than long-pulse CO2 lasers in dental hard tissue processing.

DOI： 10.1117/12.2284944

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

To realize an ultraviolet laser with high beam quality and high output power, we are developing a master oscillator power amplifier system for a longitudinally excited gas laser. In this system, high beam quality is produced by an oscillator stage, and high output power is produced by an amplifier stage. Here, the beam profile of the longitudinally excited gas N-2 laser had a quasi-Gaussian shape when using a large-diameter discharge tube, which enabled the use of the amplifier stage. The discharge tube consisted of a dielectric pipe with an inner diameter of 14 mm and a length of 30 cm. The discharge tube was covered with a metallic tube for pre-ionization. The strength and spatial distribution of pre-ionization were optimized by adjusting the gap between the metallic tube and the discharge tube. The uniform discharge achieved by controlling the pre-ionization produced a quasi-Gaussian laser beam profile with a correlation factor of 0.995 13, a laser pulse energy of 343 mu J, and an input energy of 2.95 J. Published by AIP Publishing.

DOI： 10.1063/1.4979805

Web of Science

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

A longitudinally excited CO2 laser driven with a reverse recovery characteristics of high voltage diode has been developed. A diode is used to control the high voltage pulse as an opening switch. Power supply for longitudinally excited CO2 laser is composed of a pulse generator, transformer, capacitor, and a diode, is very simple. Laser oscillation has been successfully achieved, several tens of mJ in laser energy has been obtained.

DOI： 10.1117/12.2249734

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser with a long external cavity and investigated the drilling characteristics of polycarbonate resin. The CO2 laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 13 mm, a pulse power supply, a step-up transformer, a storage capacitance, and a long external optical cavity with a cavity length of 175 cm and an aperture of 9 mm. The CO2 laser produced a short pulse that had a spike pulse with the width of 282 ns and the energy of 0.45 mJ, a pulse tail with the length of 66.9 mu s and the energy of 15.65 mJ, and a good circular beam. In a processing system, a ZnSe focusing lens with the focal length of 50 mm was used and the location of the focal plane was that of the sample surface. In the drilling of polycarbonate resin by the CO2 laser, the drilling characteristics depended on the number of pulses and the fluence was investigated. Clear drilling without carbonization was produced by the irradiation of 50 pulses or less with the fluence of 19 J/cm(2) and the irradiation of 100 pulses or less with the fluence of 8 J/cm(2). The clear drilling with the deepest depth in this work was 403 mu m at the 50 pulses irradiation with the fluence of 19 J/cm(2). The number of pulses and the fluence can control thermal influence in the CO2 laser processing of polycarbonate resin.

DOI： 10.1117/12.2251174

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser system that was constituted of two or three laser tubes and a single driving circuit. The multiple laser tubes simultaneously produced almost the same short laser pulses with a spike pulse width of about 164 ns and a pulse tail length of about 74 mu s with a single driving circuit. The double-tube system was constituted of two 30 cm-long laser tubes with inner diameters of 13 mm and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 13 mm-tube was 23.3 mJ, and that of the 16 mm-tube was 21.9 mJ at a gas pressure of 4.2 kPa (CO2:N-2:He = 1:1:2). The triple-tube system was constituted of three 30 cm-long laser tubes with inner diameters of 9 mm, 13 mm, and 16 mm and a single driving circuit with an input energy of 2.18 J. The output energy of the 9 mm tube was 15.9 mJ, that of the 13 mm tube was 24.1 mJ, and that of the 16 mm tube was 19.2 mJ at a gas pressure of 4.2 kPa. With the same driving circuit and the same input energy, the total output energies of the multi-tube laser systems were higher than the output energy of a single-tube system.

DOI： 10.1117/12.2246075

Web of Science

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

A short-pulse longitudinally excited CO2 laser operating at a high repetition rate was developed. The discharge tube was made of a 45 cm-long or 60 cm-long dielectric tube with an inner diameter of 16 mm and two metallic electrodes at the ends of the tube. The optical cavity was formed by a ZnSe output coupler with a reflectivity of 85% and a high-reflection mirror. Mixed gas ( CO2:N-2:He = 1:1:2) was flowed into the discharge tube. A high voltage of about 33 kV with a rise time of about 200 ns was applied to the discharge tube. At a repetition rate of 300 Hz and a gas pressure of 3.4 kPa, the 45 cm-long discharge tube produced a short laser pulse with a laser pulse energy of 17.5 mJ, a spike pulse energy of 0.2 mJ, a spike width of 153 ns, and a pulse tail length of 90 mu s. The output power was 5.3 W. The laser pulse waveform did not depend on the repetition rate, but the laser beam profile did. At a low repetition rate of less than 50 Hz, the laser beam had a doughnut-like shape. However, at a high repetition rate of more than 150 Hz, the discharge concentrated at the center of the discharge tube, and the intensity at the center of the laser beam was higher. The laser beam profile depended on the distribution of the discharge. An output power of 7.0 W was achieved by using the 60 cm-long tube.

DOI： 10.1117/12.2245529

Web of Science

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We developed an azimuthally polarized pulse-periodic CO2 laser for high-performance drilling applications. We discovered an anomalous enhancement in the drilling rate with the azimuthally polarized beam compared to that with radially or randomly polarized beams. We drilled 0.45 mm-thick carbon fiber reinforced plastic (CFRP) using a focusing lens with a focal length of 50 mm and a numerical aperture (NA) of 0.09. The conditions other than polarization states were identical for all the experiments. The azimuthally polarized beam exhibited a drilling rate more than 10 times greater on average than those of the other two polarizations.

DOI： 10.1088/1054-660X/26/9/096001

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser that produces a short laser pulse with the almost same spike-pulse energy of about 0.8 mJ and the controllable pulse-tail energy of 6.33-23.08 mJ. The laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 9 mm, a pulse power supply, a step-up transformer, a storage capacitance and a spark-gap switch. The dependence of SiO2 glass drilling on the fluence and the number was investigated by four types of short-pulse CO2 lasers. In this work, the effective short laser pulse with the spike pulse energy of 0.8 mJ for SiO2 glass drilling was the laser pulse with the pulse tail energy of 19.88 mJ, and produces the drilling depth per the fluence of 124 mu m/J/cm(2).

DOI： 10.1117/12.2211565

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser that produces a short laser pulse with the almost same spike-pulse energy of about 0.8 mJ and the controllable pulse-tail energy of 0-21.26 mJ. The laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 9 mm, a pulse power supply, a step-up transformer, a storage capacitance and a spark-gap switch. In single-shot irradiation using these laser pulses, the dependence of the drilling depth of dry ivory samples on the fluence was investigated. The drilling depth increased with the fluence in the same laser pulse waveform. In this work, the effective short laser pulse for the hard tissue drilling was the laser pulse with the spike pulse energy of 0.87 mJ and the pulse tail energy of 6.33 mJ that produced the drilling depth of 28.1 mu m at the fluence of 3.48 J/cm(2) and the drilling depth per the fluence of 7.27 mu m/J/cm(2).

DOI： 10.1117/12.2211557

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser that produces a short laser pulse. The laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 9 mm, a pulse power supply, a step-up transformer, a storage capacitance, and a spark-gap switch. The laser pulse had a spike pulse and a pulse tail. The energy of the pulse tail was controlled by adjusting medium gas. Using three types of CO2 laser pulse with the same spike-pulse energy and the different pulse-tail energy, the characteristics of the hole drilling of synthetic silica glass was investigated. Higher pulse-tail energy gave deeper ablation depth. In the short laser pulse with the spike-pulse energy of 1.2 mJ, the spike pulse width of 162 ns, the pulse-tail energy of 24.6 mJ, and the pulse-tail length of 29.6 mu s, 1000 shots irradiation produced the ablation depth of 988 mu m. In the hole drilling of synthetic silica glass by the CO2 laser, a crackfree process was realized.

DOI： 10.1117/12.2077924

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We developed a longitudinally excited CO2 laser with a tandem discharge tube. The tandem scheme was constituted of two 30-cm long discharge tubes connected with an intermediate electrode. Two parts, each consisting of a charged capacitance and a 30-cm long discharge tube, were electrically connected in parallel and switched by a spark gap. The tandem scheme produced a short laser pulse like that of a TEA-CO(2)Z laser with a charging voltage of -24.8 kV, which was smaller than the -40.0 kV charging voltage of our previous CO2 laser. At a gas pressure of 3.8 kPa, the spike pulse width was 145 ns, the pulse tail length was 58.8 mu s, the output energy was 52.0 mJ, and the spike pulse energy was 2.4 mJ. We also investigated the dependence of the laser pulse and the discharge voltage on gas pressure. (C) 2014 AIP Publishing LLC.

DOI： 10.1063/1.4898183

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser with a tail-free short laser pulse. In a discharge tube, two structures were researched. One is a shingle scheme that is constituted of a 45 cm-long discharge tube. Another is a tandem that is constituted of two 30 cm-long discharge tubes connected with an intermediate electrode were used. In gas media, CO2-rich mixture (CO2: N-2 = 20: 1) was used to reduce a laser pulse tail. The laser system did not require expensive and scarce helium. A fast discharge (<1 mu s) in a low gas pressure (<1.8 kPa) produced a tail-free laser pulse with the pulse width of about 100 ns. The single scheme produced an output energy of 4.7 mJ by a charging voltage of -36.3 kV, and the tandem scheme produced an output energy of 9.3 mJ by a charging voltage of -25.2 kV. The tandem scheme produced higher spike pulse by lower voltage than the single scheme. Therefore, the tandem scheme will be effective in longitudinally excited CO2 lasers with simple and compact designs.

DOI： 10.1117/12.2071059

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We developed a longitudinally excited N-2 laser (337 nm) with low beam divergence without collimator lenses. The N-2 laser consisted of a 30 cm long Pyrex glass tube with an inner diameter of 2.5 mm, a normal stable resonator formed by flat mirrors, and a simple, novel driver circuit. At a N-2 gas pressure of 0.4 kPa and a repetition rate of 40 Hz, the N-2 laser produced a circular beam with an output energy of 2.6 mu J and a low full-angle beam divergence of 0.29 mrad due to the uniform discharge formed by the longitudinal excitation scheme, the long cavity with the small aperture, and the low-input energy oscillation. (C) 2014 AIP Publishing LLC.

DOI： 10.1063/1.4894263

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We developed a longitudinally excited CO2 laser that produces a short laser pulse with a circular beam and a low divergence angle. The laser was very simple and consisted of a 45-cm-long alumina ceramic pipe with an inner diameter of 9 mm, a pulse power supply, a step-up transformer, a storage capacitance, and a spark-gap switch. The laser pulse had a spike pulse width of 103 ns and a pulse tail length of 32.6 mu s. The beam cross-section was circular and the full-angle beam divergence was 1.7 mrad. The laser was used to drill ivory samples without carbonization at fluences of 2.3-7.1 J/cm(2). The drilling depth of the dry ivory increased with the fluence. The drilling mechanism of the dry ivory was attributed to absorption of the laser light by the ivory.

DOI： 10.1117/12.2038325

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We developed a modified driver circuit composed of a capacitance and a spark gap, called a directdrive circuit, for a longitudinally excited gas laser. The direct-drive circuit uses a large discharge impedance caused by a long discharge length of the longitudinal excitation scheme and eliminates the buffer capacitance used in the traditional capacitor-transfer circuit. We compared the directdrive circuit and the capacitor-transfer circuit in a longitudinally excited N-2 laser (wavelength: 337 nm). Producing high output energy with the capacitor-transfer circuit requires a large storage capacitance and a discharge tube with optimum dimensions (an inner diameter of 4 mm and a length of 10 cm in this work); in contrast, the direct-drive circuit requires a high breakdown voltage, achieved with a small storage capacitance and a large discharge tube. Additionally, for the same input energy of 792 mJ, the maximum output energy of the capacitor-transfer circuit was 174.2 mu J, and that of the direct-drive circuit was 344.7 mu J. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798643]

DOI： 10.1063/1.4798643

Web of Science

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：(MISC) Prompt report, short report, and research note, etc. (bulletin of university, research institution)  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

A longitudinally excited CO2 laser pumped by a fast discharge emits a short laser pulse, similarly to TEA and Q-switched CO2 lasers. We investigated the relation between the discharge length and the laser pulse characteristics to develop a longitudinally excited CO2 laser producing a high spike laser pulse. We examined discharge lengths of 30, 45, and 60 cm, using the same mirrors and the same excitation circuit with the same input energy. A longer discharge length increased the discharge volume and improved the laser output energy. However, the longer discharge length caused a long discharge formation time (a slow fall time of the discharge voltage) due to the higher discharge impedance, which resulted in a long laser pulse tail. Therefore, the longitudinally excited CO2 laser had optimum conditions for obtaining a high spike laser pulse effectively. © 2013 Springer Science+Business Media New York.

DOI： 10.1007/s10762-013-9966-6

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

In a longitudinally excited CO2 laser with a short laser pulse, similarly to TEA and Q-switched CO2 lasers, a fast discharge is very important. We investigated the use of a fast discharge circuit to obtain a high spike laser pulse in a longitudinally excited CO2 laser. We compared a traditional capacitor-transfer circuit having a buffer capacitance of 700 pF with our direct-drive circuit in which the buffer capacitance is removed. The direct-drive circuit produced a fast discharge and a high spike laser pulse. We also investigated the effect of a resistance connected in parallel with the discharge tube to eliminate low discharge current after the main discharge. A low resistance of 1 k Omega or less acted as a shunt resistance. The shunt resistance was effective in decreasing the energy of the laser pulse tail at high gas pressure.

DOI： 10.1007/s10762-013-9965-7

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We have developed a longitudinally excited CO2 laser without a high-voltage switch. The laser produces a short laser pulse similar to those from TEA and Q-switched CO2 lasers. This system, which is the simplest short-pulse CO2 laser yet constructed, includes a pulsed power supply, a high-speed step-up transformer, a storage capacitor, and a laser tube. At high pressure (4.2 kPa and above), a rapid discharge produces a short laser pulse with a sharp spike pulse. In mixed gas (CO2: N-2: He = 1: 1: 2) at a pressure of 9.0 kPa, the laser pulse contains a spike pulse of 218 ns and has a pulse tail length of 16.7 mu s.

DOI： 10.1007/s10762-012-9892-z

Web of Science

Language：Japanese   Publishing type：Research paper (research society, symposium materials, etc.)  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We have developed a longitudinally excited CO2 laser with a short laser pulse similar to that of TEA and Q-switched CO2 lasers. A capacitor transfer circuit with a low shunt resistance provided rapid discharge and a sharp spike pulse with a short pulse tail. Specifically, a circuit with a resistance of 10 M Omega provided a spike pulse width of 103.3 ns and a pulse tail length of 61.9 mu s, whereas a circuit with a shunt resistance of 100 Omega provided a laser pulse with a spike pulse width of 96.3 ns and a pulse tail length of 17.2 mu s. The laser pulses from this longitudinally excited CO2 laser were used for processing a human tooth without carbonization and for glass marking without cracks.

DOI： 10.1007/s10762-009-9542-2

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Plasma Science and Nuclear Fusion Research  

Red-fluorine-atom (Red-F^* ) laser oscillation (λ = 630-780 nm) and strong fluorescence of VUV-F₂ emission (λ = 157 nm) are observed in a lamp-like discharge in a longitudinal discharge excitation tube. The laser tube consists of a 30 cm long Pyrex glass pipe with an inner diameter of 2 mm, and a step-up transformer coupled directly to the discharge tube without a high-voltage switch. Excitation is produced by wall-coupled discharge. The laser pulse width is 6.1 ns at 100 Torr (13.3 kPa, with an F₂ concentration of 5 %) when a slow-rising voltage pulse of -40 kV (rise time: 253 ns) is applied. VUV-F₂ emission of a 24.5 ns (FWHM) pulse width was generated simultaneously with the red-F^* laser.

DOI： 10.1585/pfr.3.037

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We have developed novel excitation circuits without high-voltage switches for two longitudinally excited N(2) lasers (wavelength: 337 nm). One uses a single tube without a trigger and the other uses a tandem tube with a trigger. In both systems, the discharge tube acts as a switch. In the single-tube system, the laser output energy was 125.8 mu J and the efficiency was 0.16% at 18 Torr (2.4 kPa) when a slow-rising voltage pulse of -28 kV was applied (rise time: 21.3 mu s). In the tandem-tube system, the laser output energy was 259.4 mu J and the efficiency was 0.11% at 18 Torr when a slow-rising voltage pulse of -48 kV was applied (rise time: 27 mu s). (C) 2008 American Institute of Physics. (C) 2008 American Institute of Physics.

DOI： 10.1063/1.2936872

Web of Science

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Nitrogen laser oscillation is observed in a lamplike discharge within a longitudinal excitation tube. The laser consists of a 30-cm-long Pyrex glass tube with ail inner diameter of 2.5 film and a step-Lip transformer directly coupled to the discharge tube without a high-voltage switch. The excitation is produced by wall-coupled discharge. The laser Output energy is 1.7 mu l at 12 Torr (1.6 kPa) and 40 Hz when applying a slow-rising Voltage Pulse of 37 kV (rise time of 572 ns).

DOI： 10.1143/JJAP.45.1651

Web of Science

Language：Japanese   Publishing type：Research paper (research society, symposium materials, etc.)  

Event date： 2024.1 - 2024.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, California   Country：United States  

Event date： 2024.1 - 2024.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, California   Country：United States  

Event date： 2024.1

Language：Japanese   Presentation type：Poster presentation  

Venue：日本科学未来館   Country：Japan  

Event date： 2024.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：日本科学未来館   Country：Japan  

Event date： 2023.12

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：大阪公立大学I-siteなんば   Country：Japan  

Event date： 2023.12

Language：English   Presentation type：Oral presentation(general)  

Venue：Sheraton Grand Hiroshima Hotel, Hiroshima   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Poster presentation  

Venue：熊本城ホール   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Poster presentation  

Venue：愛知工業大学自由ヶ丘キャンパス   Country：Japan  

Event date： 2023.6

Language：English   Presentation type：Poster presentation  

Venue：Hirosaki Bunka Center, Hirosaki, Aomori   Country：Japan  

Event date： 2023.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa   Country：Japan  

Event date： 2023.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Poster presentation  

Venue：上智大学，東京  

Event date： 2023.3

Language：Japanese   Presentation type：Poster presentation  

Venue：上智大学，東京  

Event date： 2023.1

Language：Japanese   Presentation type：Poster presentation  

Venue：ウインクあいち，愛知県  

Event date： 2023.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：ウインクあいち，愛知県  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：東北大学川内キャンパス，宮城県  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：東北大学川内キャンパス，宮城県  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：西之表市民会館，鹿児島  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：西之表市民会館，鹿児島  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：西之表市民会館，鹿児島  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：西之表市民会館，鹿児島  

Event date： 2022.9

Language：Japanese   Presentation type：Poster presentation  

Venue：西之表市民会館，鹿児島  

Event date： 2022.4

Language：English   Presentation type：Poster presentation  

Venue：Kunibiki Messe, Matsue, Japan  

Event date： 2022.4

Language：English   Presentation type：Oral presentation(general)  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

Venue：青山学院大学相模原キャンパス  

Event date： 2022.3

Language：Japanese   Presentation type：Poster presentation  

Venue：青山学院大学相模原キャンパス  

Event date： 2022.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：Online  

Event date： 2022.1

Language：Japanese   Presentation type：Poster presentation  

Venue：Online  

Event date： 2021.9

Language：Japanese   Presentation type：Poster presentation  

Venue：Online  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：online  

Event date： 2020.10

Language：English   Presentation type：Poster presentation  

Venue：Online  

Event date： 2020.10

Language：English   Presentation type：Poster presentation  

Venue：Online  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：オンライン  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：オンライン  

Event date： 2020.9

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン  

Event date： 2020.9

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン  

Event date： 2020.9

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン  

Event date： 2020.3

Language：Japanese   Presentation type：Poster presentation  

Venue：上智大学四谷キャンパス，東京都  

Event date： 2020.3

Language：Japanese   Presentation type：Poster presentation  

Venue：上智大学四谷キャンパス，東京都  

Event date： 2020.1

Language：Japanese   Presentation type：Poster presentation  

Venue：仙台国際センター，宮城県  

Event date： 2019.11

Language：English   Presentation type：Poster presentation  

Venue：Ceratopia Toki, Toki, Gifu, Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Poster presentation  

Venue：北海道大学札幌キャンパス，北海道  

Event date： 2019.9

Language：English   Presentation type：Poster presentation  

Venue：The Westin Maui Resort & Spa, Maui-Hawaii, USA  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation(invited, special)  

Venue：琉球大学工学部，沖縄県  

Event date： 2019.9

Language：Japanese   Presentation type：Poster presentation  

Venue：岩手大学上田キャンパス，岩手県  

Event date： 2019.9

Language：Japanese   Presentation type：Poster presentation  

Venue：岩手大学上田キャンパス  

Event date： 2019.5

Language：English   Presentation type：Poster presentation  

Venue：Hiroshima International Conference Center, Hiroshima, Japan  

Event date： 2019.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Poster presentation  

Venue：山梨大学甲府キャンパス  

Event date： 2019.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京工業大学大岡山キャンパス  

Event date： 2019.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東京工業大学大岡山キャンパス  

Event date： 2019.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, California, United States  

Event date： 2019.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：東海大学高輪キャンパス  

Event date： 2018.10

Language：English   Presentation type：Poster presentation  

Venue：Beijing International Convention Center, Beijing, China  

Event date： 2018.9

Language：Japanese   Presentation type：Poster presentation  

Venue：名古屋国際会議場，愛知県名古屋市  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：イーグレひめじ，兵庫県姫路市  

Event date： 2018.9

Language：English   Presentation type：Oral presentation(general)  

Venue：Palau de Congressos de Tarragona, Tarragona, Spain  

Event date： 2018.6

Language：English   Presentation type：Poster presentation  

Venue：Heriot-Watt University, Edinburgh, UK  

Event date： 2018.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2018.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Poster presentation  

Venue：早稲田大学西早稲田キャンパス  

Event date： 2018.2

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：山梨大学，山梨県甲府市  

Event date： 2018.2

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：山梨大学，山梨県甲府市  

Event date： 2018.1

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2018.1

Language：Japanese   Presentation type：Oral presentation(invited, special)  

Venue：京都市勧業館みやこめっせ，京都府京都市  

Event date： 2017.9

Language：Japanese   Presentation type：Poster presentation  

Venue：室蘭工業大学  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：室蘭工業大学  

Event date： 2017.9

Language：Japanese   Presentation type：Poster presentation  

Venue：室蘭工業大学  

Event date： 2017.9

Language：Japanese   Presentation type：Poster presentation  

Venue：福岡国際会議場  

Event date： 2017.6

Language：English   Presentation type：Poster presentation  

Venue：Messe Munchen, Munich, Germany  

Event date： 2017.6

Language：English   Presentation type：Poster presentation  

Venue：Toyama International Conference, Toyama, Japan  

Event date： 2017.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Poster presentation  

Venue：パシフィコ横浜  

Event date： 2017.1

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2017.1

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2017.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：徳島大学常三島キャンパス  

Event date： 2016.11

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：東京都市大学横浜キャンパス  

Event date： 2016.11

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：官公労共済会八重山会館  

Event date： 2016.10

Language：English   Presentation type：Poster presentation  

Venue：Beijing International Convention Center, Beijing, China  

Event date： 2016.10

Language：English   Presentation type：Poster presentation  

Venue：Beijing International Convention Center, Beijing, China  

Event date： 2016.9

Language：Japanese   Presentation type：Poster presentation  

Venue：朱鷺メッセ  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：朱鷺メッセ  

Event date： 2016.5

Language：English   Presentation type：Poster presentation  

Venue：Wyndham Grand Xi’an South, Xi’an, China  

Event date： 2016.5

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2016.5

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：東京工業大学大岡山キャンパス  

Event date： 2016.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2016.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2016.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：名城大学  

Event date： 2016.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：名城大学  

Event date： 2016.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：名城大学  

Event date： 2015.12

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：防衛大学校  

Event date： 2015.11

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：宮古島マリンターミナル  

Event date： 2015.11

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：宮古島マリンターミナル  

Event date： 2015.10

Language：English   Presentation type：Poster presentation  

Venue：Melbourne Convention and Exhibition Center, Melbourne, Australia  

Event date： 2015.9

Language：Japanese   Presentation type：Poster presentation  

Venue：金沢大学角間キャンパス  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：名古屋国際会議場  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：名古屋国際会議場  

Event date： 2015.7

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：理化学研究所東京連絡事務所  

Event date： 2015.5

Language：English   Presentation type：Poster presentation  

Venue：Kitakyusyu, International Congress Center, Fukuoka, Japan  

Event date： 2015.3

Language：Japanese   Presentation type：Poster presentation  

Venue：東海大学湘南キャンパス  

Event date： 2015.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2015.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：東海大学高輪キャンパス  

Event date： 2014.10

Language：English   Presentation type：Poster presentation  

Venue：Beijing International Convention Center, Beijing, China  

Event date： 2014.9

Language：Japanese   Presentation type：Poster presentation  

Venue：北海道大学札幌キャンパス  

Event date： 2014.6

Language：English   Presentation type：Poster presentation  

Venue：Radisson BLU Hotel Lietuva Conference center, Vilnius, Lithuania  

Event date： 2014.3

Language：Japanese   Presentation type：Poster presentation  

Venue：青山学院大学相模原キャンパス  

Event date： 2014.2

Language：English   Presentation type：Poster presentation  

Venue：The Moscone Center, San Francisco, U.S.A.  

Event date： 2014.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：北九州国際会議場  

Event date： 2014.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：北九州国際会議場  

Event date： 2013.9

Language：Japanese   Presentation type：Poster presentation  

Venue：同志社大学京田辺キャンパス  

Event date： 2013.7

Language：English   Presentation type：Oral presentation(general)  

Venue：Toki Messe, Niigata, Japan  

Event date： 2013.7

Language：English   Presentation type：Poster presentation  

Venue：Toki Messe, Niigata, Japan  

Event date： 2013.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2013.4

Language：English   Presentation type：Poster presentation  

Venue：Pacifico Yokohama, Kanagawa, Japan  

Event date： 2013.3

Language：Japanese   Presentation type：Poster presentation  

Venue：神奈川工科大学  

Event date： 2013.3

Language：Japanese   Presentation type：Poster presentation  

Venue：神奈川工科大学  

Event date： 2013.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：姫路商工会議所  

Event date： 2013.1

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：姫路商工会議所  

Event date： 2012.11

Language：English   Presentation type：Poster presentation  

Venue：Taipei International Convention Center, Taipei, Taiwan  

Event date： 2012.9

Language：Japanese   Presentation type：Poster presentation  

Venue：愛媛大学  

Event date： 2012.3

Language：Japanese   Presentation type：Poster presentation  

Venue：早稲田大学早稲田キャンパス  

Event date： 2012.2

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：TKP仙台カンファレンスセンター  

Event date： 2012.2

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：TKP仙台カンファレンスセンター  

Event date： 2011.8

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：山形大学  

Event date： 2011.3

Language：Japanese   Presentation type：Oral presentation(general)  

Venue：神奈川工科大学  

Event date： 2006.5

Language：English   Presentation type：Oral presentation(general)  

Venue：Kyoto Research Park, Kyoto, Japan