| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve problems in that scattering light is emitted to a connecting part, which insulates and connects a mirror and the space of discharging means, with the result that temperature of this joining part increases, leading to a decrease in the insulation resistance of the insulation joining part, and shift of discharge to an insulation part.SOLUTION: In the present invention, in order to solve the foregoing problems, projections and recesses for scattering absorbing miscellaneous light are provided on the internal surface of a connecting part that insulates and connects a mirror and the space of discharging means. The shape of each of the recessed and projections is right-angle triangle. The length of the hypotenuse of each triangle is not less than four times but not greater than six times with respect to the wavelength of a laser beam. The inclination angle of the recesses and projections with respect to the direction of an optical axis is 10 to 25 degrees. The right angle part of each of the right-angle triangular projections and recesses of the non-discharge tube joining a partial reflector and a discharging part is oriented toward the partial reflector. The right-angle triangular projections and recesses of the discharge tube joining a total reflector and the discharging part are oriented toward the total reflector. The material of the joining part is glass or ceramic.</p> |
