| 摘要 |
PURPOSE:To cool a light guide and to prevent the light guide from breaking down owing to absorbed heat by providing a cavity which extends lengthwise, i.e. cooling passage in at least one thick internal part of a division member. CONSTITUTION:Joint surface parts of four long-sized division members 6 and 6, and 7 and 7 having linear section are fixed with an adhesive to form square section. Each of the division parts form one of a top and a reverse and a right and a left flank and the cavity which extends lengthwise, i.e. cooling passage 8 is formed in the thick part of the division members forming intermediate, top, and reverse surfaces. A refrigerant made of gas or liquid is admitted into and discharged from the passage 8 through its entrance and exit to cool the light guide. The division part 6 having this cooling passage 8 is made into a division member having a specular surface by extruding a heated and softened metallic material by using a combinational die. Thus, the breakage of the light guide due to absorbed heat is prevented. |
