Patent ID: 7803455

Claim:
An optical element comprising: a substrate; and an antireflection film formed on a surface of the substrate comprising: a plurality of lower refractive index layers having a refractive index equal to or more than 1.4 and equal to or less than 1.6 for a light flux with a wavelength of 450 mm; and a plurality of higher refractive index layers having a refractive index equal to or more than 1.8 and equal to or less than 2.2 for a light flux with a wavelength of 450 nm, wherein the plurality of lower refractive index layers and the plurality of higher refractive index layers are layered alternately, each of the plurality of the lower refractive index layers comprises a main component, and at least two of the plurality of the lower refractive index layers comprise a side component, and percentages for the side component in at least two of the plurality of the lower refractive index layers are different, and each of the plurality of the high refractive index layer adjoins at least one lower refractive index layer comprising a side component.