Ultraviolet optical part having coat of ultraviolet optical thin film, and wavelength-changing device and ultraviolet light source unit having coat of ultraviolet optical thin film

摘要

The present invention provides an ultraviolet optical part having an ultraviolet optical thin film having a high durability against ultraviolet rays. The ultraviolet optical part is used in connection with ultraviolet rays continuously generated in a wavelength of 200 through 300 nm, and comprises an optical component and an ultraviolet optical thin film formed the optical component, wherein the ultraviolet optical thin film comprises a material having a thermal conductivity of 0.01 J. multidot.cm.sup.-1 ·sec.sup.-1 ·K.sup.-1 or greater. The ultraviolet optical thin film may comprise an HfO.sub.2 layer 10 and MgF. sub.2 layer 11, or may comprise an HfO.sub.2 layer 10, an MgO layer 12, and MgF.sub.2 layer 11. Further, the present invention provides a wavelength-changing device having a high durability against ultraviolet rays, the wavelength-changing device comprising a non-linear optical crystal and the ultraviolet optical thin film formed on the optical crystal. The non-linear optical crystal may comprise BBO or KDP.