APPARATUS FOR CAUSING LASER BEAM TO IRRADIATE IN VACUUM

PURPOSE:To provide a vacuum laser beam irradiating apparatus where gas generated from a material to be irradiated with laser beam irradiation is screened with an inner aperture plate and sticking of impurity to expensive outer aperture plate can be prevented, by arranging the outer aperture plate between a cylindrical body arranged in a vacuum chamber and the atmosphere and the inner aperture plate in vacuum inside of this outer aperture plate. CONSTITUTION:After reducing pressure in the vacuum chamber 3 into high vacuum under condition of laying the material 6 to be irradiated on an irradiated material laying table 5, the laser beam is emitted from a laser beam oscillator 10. Then, the laser beam is transmitted through the optional opening part 19d in a backup member 19 through the outer aperture plate 13 in the vacuum chamber 3 and introduced to the vacuum chamber 3 through vertically moving member 22 and a first plate 23 and further through the inner aperture plate 16 to irradiate the material 6 to be irradiated. By this irradiation, the gas is generated from the material 6 to be irradiated, but a large part of the gas is screened with the inner aperture plate 16 arranged inside of the outer aperture plate 15 and on the outer aperture plate 15, sticking of impurity contained in the gas is little. Therefore, the expensive outer aperture plate 15 is not required to exchange often and economical burden is reduced.