| 摘要 |
PURPOSE:To cool a mirror, to prevent its dew condensation and to prevent the dust invasion into a laser beam passage by performing a heat exchange by introducing an air to the back face of each mirror and by touching it with the fin touching with the mirror back face. CONSTITUTION:The air fed from an air feeding port 6 is led to the 1st-3rd beam passage 50a-50c in a work head 27 to perform a heat exchange by touching a fin 54 through an air path 55 at the part of each mirror 42, 43, 44. It is exhausted to the atmosphere from the air exhausting port 54 pierced on a cover 51 after entering into a chamber 52. On the other hand, the air is led to the 2nd, 1st beam pipe from the 1st beam path 50a and each mirror is air- cooled similarly. The cooling of mirrors and dew condensation are thus prevented, the piping is reduced and the construction is simplified. |
