An experiment on the treatment of tinea pedis, common athlete's foot, infections was done using a pulsed CO₂ laser having an output energy of 3 joule/pulse and pulse duration of 0.5 psec. Based on the results by the culture experiment, the ratio of the number of the samples having a cure rate of above 70% to all the samples is about 0.55 for thin skin and 0.35 for thick skin. The itchiness on the blistered infected parts virtually disappers within a few hours after the laser irradiation and the vesicles almost completely disapper within about 2 days.

View full abstract

Using the intense electron beam excited mixtures of molecular fluorine and helium; we have developed a joule-level 157-nm F₂ laser. Maximum laser energy of 1.84 J with a pulse width of 35 ns (53 MW) and an intrinsic efficiency of 1.4% was obtained using a 6 atm mixture of He/F₂=99.88/0.12 (%). It corresponds to 11.5 J of the laser energy extracted from the whole electron beam aperture of 9 cm in diameter. It is found for the first time that the Ne-addition to the normal He/F₂ mixture is very useful to decrease the high operat-ing pressure of the mixture.

View full abstract

Kinetic process and lasing characteristics of IF halogen lasers are described for electron-beam pumped Ar/CF₃I/NF₃gas mixtures. According to individual fluorescence yields of IF (D′-A′), I₂ (D′-A′) and Ar F (B-X), it is found that (1) the I (⁴P) species are confirmed as the common precursor to IF (D′) and I₂ (D′), and (2) the formation of I₂ (D′) competes with the formation of IF (D′) because the ratio of IF fluorescence yield to the I₂ fluorescence yield is nearly equal and the formation of I₂ (D′) leads to the reduction of the number of I (⁴P). We also investigated the performance characteristics of the IF laser., It is found that the lasing is delayed due to the absorption by the I₂ (X) that causes the extraction of IF laser energy to be decreased.

View full abstract

Arrayed KDP cells with 20cm aperture for third harmonic generation of two beam Glass Laser System GMII has been constructed. The doubler with four segments of KDP crystals and the tripler with four were altogether assembled in one cell. Each crystal has been finished with a diamond turning machine. A crystal orientation and measuring system with an accuracy of 2″″ using repetitive Q-switched YAG laser has been used to measure the phase matching angle and to determine segment-to-segment angle correction. The angular accurracy of each KDP segment for the doubler was set less than 12″″ and for the tripler, 6″″. Propylene carbonate was used for index matching fluid. Maximum energy conversion efficiency of 60% for third harmonic generation was obtained at the input energy of 60J (2.2 GW/cm², 100ps pulse), and the near field pattern was uniform.

View full abstract