| 摘要 |
An optical element having a plastic substrate and an antireflection film of a lambda /4 - lambda /2 - lambda /4 or lambda /4 - lambda /4 - lambda /2 - lambda /4 type ( lambda = 500 nm) provided in that order on the plastic substrate, wherein the layer of lambda /2 is a high-refraction equivalent film containing at least three layers and having a refractive index of from 1.80 to 2.40, and the even-numbered layer of the equivalent film is an SiO2 layer is provided. The optical element having an antireflection film on a plastic substrate has good heat resistance. |
