Tetsuo Kano

Experimental trial of a hollow-core waveguide used as an absorption cell for concentration measurement of NH 3 gas with a CO 2 laser

The basic idea of using a hollow-core waveguide as an absorption cell in a spectroscopic gas measurement system is proposed. Measurements of NH3 gas concentration were made with different absorption methods at an absorption wavelength of 10.719 μm and a nonabsorption wavelength of 10.697 μm and by using a 1-m hollow-core waveguide whose transmission loss was approximately 1 dB/m in a CO2 laser with wavelengths ranging from 10.261 to 10.719 μm. The hollow-core part of the waveguide was filled with NH3 gas to form an absorption cell through which the two wavelengths were transmitted. The minimum detectable concentration level of the measurement system was limited to 5 parts in 106 because of the limitations of the manometers used in the gas-concentration monitor.

Simultaneous three primary color laser emissions from dye mixtures

Simultaneous two‐ and three‐band laser emissions were obtained in a process of mixing two and three kinds of dyes excited by a nitrogen laser. They were blue, green, and yellow in a coumarin 460 (C460)/disodium fluorescein (DF)/rhodamine 610 (R610) dye mixture, and blue, green, and red in a C460/DF/rhodamin 640 (R640) dye mixture. Strong energy transfers from DF to R610 and to R640 were shown. R610 and R640 laser emissions on mixing with DF were obtained at very low concentrations. They were 4×10−6 mol/l  for R610 and 1×10−5 mol/l  for R640, compared to the lasing threshold concentration of 1×10−4 and 2×10−4 mol/l  of each dye alone. Also, the R610 radiation moved about 35 nm to a shorter wavelength at the reduced concentration.

Spectral characteristics of a short-pulse red-green-blue dye mixture laser

Three-primary-color laser emissions of blue, green, and red were simultaneously obtained by using a Coumarin 460 (C460)/Disodium Fluorescein (DF)/Cresyl Violet (CV) mixture and a C460/DF/LD690 (LD) dye mixture excited by a nitrogen laser. The center wavelengths were 455 nm (C460; 4.8 x 10(-3) mol/L), 526 nm (DF; 2.4 x 10(-4) mol/L), and 630 nm (CV; 2.2 x 10(-4) mol/L) in the C460/DF/CV dye mixture laser, and 466 nm (C460; 4.8 x 10(-3) mol/L), 521 nm (DF; 2.4 x 10(-4) mol/L), and 650 nm (LD; 1.2 x 10(-3) mol/L) in the C460/DF/LD dye mixture laser. The pulse widths of the dye mixture lasers were several nanoseconds. The differences in oscillation wavelength (wavelength shift caused by mixing) and threshold concentration among the three dye mixtures, two dye mixtures, and the individual dyes that were used for the mix are experimentally described. A theoretical discussion of the selection of suitable dyes and the calculated results that were obtained by using the rate equations and the laser gain equations for the estimation of suitable concentrations for the dye mixture laser are also described.

Simultaneously tunable two-wavelength dye laser using two dielectric multilayer filters

This letter describes a simultaneous tunable two-wavelength dye laser, pumped by a nitrogen laser which uses a second dielectric multilayer filter inside the laser cavity. (AIP)

Simultaneous two-band laser emissions and three primary color outputs in the superradiant mode from dye mixtures

A dye mixture of coumarin 460, disodium fluorescein, and nile blue 690 perchrolate was excited by a nitrogen laser. Simultaneous laser emissions in two spectra regions (blue and green, green and red, red and blue) were obtained in each of the two dye mixtures. Furthermore, simultaneous three primary color outputs in a superradiant mode from three dye mixtures were observed.

Effects of the gas flow rate and the circuit parameters of the spark gap side on characteristics of LC inversion TE N2 laser

Design criteria for a N2 laser with LC inversion excitation circuit are theoretically and experimentally described. Lower resistance, depending on the spark gap pressure, gave higher energy, while the inductance was independent of it. Laser energy increased with higher gas flow rate and was saturated at rates over 10 l/min. Other experimental relationships between pulse width, gas flow rate, energy, and repetition rate are described. Typically, an energy of 4.6 mJ, a peak power of 700 kW, a pulse width of 6.6 ns, and an efficiency of 0.18% was obtained at a repetition rate of 0.4 pps, a gas flow rate 10 l/min, and a voltage of 15 kV. For a higher repetition rate of 10 pps the parameters were 3 mJ, 400 kW, 7.5 ns, and 0.12%, respectively.

Simple tunable dye laser using a dielectric multilayer filter

We describe a nitrogen laser pumped dye laser tuned by a dielectric multilayer filter. The construction is simple and the adjustment of tuning is easy. It is found that the tuning is possible over a range of 10 nm from 445 to 455 nm in alcoholic solutions of coumarin 1, that the linewidth (0.8 nm) is independent of the filter tilt angle, and that the output intensity is remarkably flat over this tuning range.

Dye-mixture laser tunable in three primary color regions with a linear variable filter

The tuning characteristics of a Coumarine 460-Disodium Fluorescein-Rhodamine 640 dye-mixture laser in the blue, green, and yellow-orange regions are reported. A linear variable filter was inserted into the laser cavity as a tuning element. The tunable range was 439-485 nm in the blue region, 509-531 nm in the green region, and 592-601 nm in the yellow-orange region. Comparison of the characteristics of the one-wavelength tuning output with those of simultaneous broadband outputs in the three color regions showed that energy transfer was an important mechanism for the oscillations, especially in the longer-wavelength region, which was farthest away from a pumping wavelength.

Energy enhancement and volume effect between parallel and transverse gas flow N2 laser

The effect of gas flow parallel and transverse to the optical path and of the volume of the laser tube on N2 laser energy and pulse width was experimentally investigated. Energy enhancements of more than a factor of 2 are clearly seen in transverse flow as compared with parallel flow. Gas flowrate affects the energy more in lasers with a large volume. Pulse widths in lasers with transverse flow are shorter than those with parallel flow by about 2 ns. These results show that both the direction of gas flow and the volume of the laser tube are important parameters to adjust to increase energy and power.