| 摘要 |
PURPOSE:To protect a light source for alignment at low cost by simple constitution by forming a window to a box body by the material, the quality of which transmits visible rays and absorbs laser beams outputted from a gas laser oscillator. CONSTITUTION:A window 18 shaped to a box body 9 is formed by the material, the quality of which transmits visible rays and absorbs laser beams oscillated by a gas laser oscillator, such as quartz glass or rock crystal glass. The window 18 displays high transmittance at the wavelength lambda1 of laser beams for alignment in a visible ray region C-D, and displays low transmittance at the wavelength lambda2 of laser beams oscillated by the gas laser oscillator. When using such a window 18, He-Ne laser beams for alignment can be introduced into the laser oscillator, and CO2 laser beams emitted from a small hole 19 in a concave total reflection mirror 7 are absorbed by the window 18, and do not reach a He-Ne laser oscillator 17. |
