| 摘要 |
<p>A multilayer optical thin film (4) is formed by alternately forming SiO<SUB>2</SUB> thin films (2) and Nb<SUB>2</SUB>O<SUB>5 </SUB>thin films (3) approximately for 100 layers in total on a surface of a quartz substrate (1) having a thickness of 0.8mm or less. Since a linear expansion coefficient of the substrate (1) is small and a difference between a linear expansion coefficient of the multilayer optical thin film (4) is large, when the temperature of the substrate (1) is reduced to a normal temperature from a normal film forming state at approximately 200°C, compression stress of the multilayer optical thin film (4) and heat stress generated by temperature reduction cancel each other and deformation (warping) of the substrate (1) is reduced. Thus, a process of cutting the substrate (1) with a dicing saw and the like can be easily performed with less breakage, and surface accuracy of a cut out optical element is improved.</p> |
