| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a break and a crack from being generated in an optical coating film by a method wherein the optical coating film is formed on the surface through which a laser beam passes, of an optical element excluding the edges of the surface. SOLUTION: An optical element 1 of a structure, wherein an optical coating film 2 is formed only on a part patterned in a circular form on the center of the mirror-polished surface 1a of the element 1 and the film 2 is not formed on edge parts 1b, is formed. At this time, the narrowest width of the edge parts 1b, that is, the shortest distance between the end of the film 2 and the end parts of the surface 1a formed with the film 2 is set in a length of 0.5 to 1.5 mm. By such a way, the bus of a laser beam is ensured and the generation of the peeling of the film 2 at the end part of the film 2 and the generation of a crack in the end part of the film 2 can be prevented. Thereby, with the fraction of detect of a semiconductor laser excitation solid laser reduced, the reliability of the laser can be enhanced.</p> |
