OPTICAL FILTER AND OPTICAL APPARATUS

摘要

There is provided an optical filter of the type having absorption and with low reflection, which includes a light-transmitting substrate; and a light-absorbing gradient refractive index thin film provided on the substrate and whose refractive index changes so as to be close to the refractive index of the substrate toward the substrate side in a film thickness direction. There is also provided an optical apparatus using the optical filter.