Ken Ishikawa

Pulsed laser processing of ceramics in water

A new method for defect‐free processing of ceramics is presented. This method consists of processing ceramics in water with a Q‐switched yttrium aluminum garnet (YAG) laser. In laser machining, a recast layer and cracks are usually formed in the machined part. Using this method, these defects are not formed.

Third‐harmonic generation of an alexandrite laser in β‐BaB2O4

We report the first cascading third‐harmonic generation by light from an alexandrite laser in β‐BaB2O4. Ultraviolet (UV) light was generated by mixing the fundamental laser light with the second‐harmonic light. The calculated effective nonlinear constant for type I mixing is nearly three times larger than that for type II. Using type I mixing we demonstrated UV light generation in the wavelength region 244–259 nm with 24% mixing efficiency at maximum.

A 20 W Cr3+, Tm3+, Ho3+: YAG laser

Abstract A 2.1 μm Cr 3+ , Tm 3+ , Ho 3+ : YAG laser is operated with an output power of 20 W at 12 Hz. The laser output is successfully transmitted through a silica fibre. The laser system was designed based on the technology of an alexandrite laser oscillator.

5 kHz high repetition rate excimer laser

ties and arcing become permanent. With a laser mixture of F,/Kr/Ne = 0.2/2/ 97.8%, the charging voltage of 27 kV was loaded. Maximum laser output energy is 213 mJ/pulse. Laser beam pattern and pulse width (FWHM) are 1.2 X 2 cm2 and 16 ns, respectively. And maximum efficiency is 1.8% at charging voltage of 21 kV. The output power of 50.3 Watt is obtained continuously at a repetition rate of 470 Hz under the condition of gas flow velocity of 13 m/s. Clearance ratio is 2.3 in above optimal condition. The gas life time of KrF laser was 3 X lo6 shots.

High-repetition-rate XeC1 Excimer Laser

A high repetition rate XeC1 excimer laser has been developed. The laser gas can be circulated at a flow rate of 120 m/s uniformly in the discharge region by a 4-stage axial blower. In a Ne buffer gas mixture, an average power of 304 W was obtained at a repetition rate of 4 kHz.

2.5 kHz high-repetition-rate XeCl excimer laser

these industrial applications.For the purpose of reaching higher repetition rates, we have constructedan experimental apparatus capable of circulating laser gas uniformly at upto 100 m/s and have clarified the optimum conditions for its operation. Theaverage laser and the gas flow rate vs. the repetition rate are presentedfor both He and Ne buffer gas mixtures.2. ExperimentFigure 1 shows the conceptual cross-section of the experimental apparatuswhich is 2.0 m in length, 1.5 m in height, and 1.0 m in width. It is Teflon