| 摘要 |
PURPOSE:To enable laser oscillation of a stable and high-quality mode by causing the reflected light from the aperture's reflecting surface to depart from the optical axis of the laser beam, and to be received by an absorber which is integral or thermally connected with the aperture's beam control portion and has a cooling mechanism, thereby preventing rise in the gas temperature in the vicinity of the aperture. CONSTITUTION:A laser beam 5b incident upon an aperture 1 having a reflecting surface of a high reflectance is reflected, largely departs from the optical axis, proceeds to and all absorbed by an absorber 2 which integral with the aperture 1 and provided with a coolant passage 2. As a concrete means for providing the aperture with a high reflectance, it is considered that, for instance, copper or brass is used, the surface is planished, and a surface treatment such as gold evaporation is performed. With these, the temperature rise of the aperture due to the absorption of the laser beam is substantially reduced, thereby preventing dissolution and damage of the aperture itself as well as deterioration of the laser beam mode involving a change in the refractive index due to the gas temperature rise in the vicinity of the aperture. |
