Excimer laser with repetition rate up to 2000 Hz

摘要

Laser medical device « Maria » on the basis of KrF excimer laser with the wavelength 248 nm was made for fiber-cavernous lung tuberculosis and bronchia tuberculosis treatment. This very spectral range has maximum efficiency due to the peak of micro bacteria destruction. The main difficulty in the operation with 248 nm radiations arises in the transportation of the radiation from the laser into a tuberculosis cavern along a fiber light guide. The necessity to obtain the desirable mean power of the radiation with a low frequency of pulses it is necessary to increase the peak power in the pulse, which leads us to the destruction of the light guide. In order to bypass this restriction a unique excimer laser was developed. In this laser generation was exited with a discharge propagate along the surface of the dielectric, namely the sliding discharge. High pulse repetition rate was obtained by the thick plasma layer (thickness about 1-1.5 mm) formation by the sliding discharge, which actually use as the pumping source. The sliding discharge plasma propagates along the sapphire plate placed on massive metallic electrode. This provides the optimum conditions for electrode cooling and gives us the increase of the generation repetition rate. The sliding discharge used as pumping source lor excimer KrF laser gives us the possibility to obtain the repetition rate up to 2000 Hz without replacing the gaseous mixture. At this condition and the mean power of the generation about 20 mW (pulse duration about 10ns) the peak power was about 1 kW. This gives us the possibility to transport the UV radiation into the cavern without wave-guide destruction. This excimer laser was able to work continuously during 3 hours without replacing the gaseous mixture. This opens wide possibilities to apply excimer lasers into the medical practice.