| 摘要 |
An optical element (1) is provided with an optical film (20). The optical film (20) is provided with an aluminum oxide layer (21) which comprises aluminum oxide as the main component and which has an optical film factor (x) of 0.010 to 2.00 as defined on the basis of optical thickness (nd) and central wavelength (lambda0). Further, the optical film (20) exhibits a shift of 0.50 % or less between the first reflectance (R1) at ordinary temperature and the second reflectance (R2) at the time of heating, both reflectances being measured at the same wavelength in the central wavelength bandwidth. |
