| 摘要 |
PURPOSE:To reduce a variation in the direction of a beam by restricting the extension of a fine discharge tube due to a thermal expansion, the expansion, the deformation of a tube supporting plate due to thermal expansion to an extension to the direction of an optical axis before its suppression or deformation. CONSTITUTION:A plurality of heat sink plates 7 are secured onto the outer periphery of a fine heat sink tube 2 in a heat transfer manner, and a pair of slits 11 are formed on a tube supporting plate 5 which is also used as a heat sink plate of a predetermined position. The plate 5 is made of a flexible metal plate, and the surface of the outside of the plate is attached through auxiliary attachment plates 8, 8' by an attachment plate 9 to a base 10. Further, reinforcing rings 12, 13 having smaller diameter than the interval of the slits 11 are respectively adhered to both the faces of the plate 5. Thus, the extension, the deformation of the fine tube and the plate due to thermal expansion can be restricted to the extension in the direction of an optical axis before its suppression or deformation, and a variation in the direction of a beam can be reduced. |
