| 摘要 |
PROBLEM TO BE SOLVED: To provide an antireflection film which has high antireflection performance on light in a visible wavelength region with regard to substrates having various refractive indices and which can reduce generation of ghosts or flares, and to provide an optical element and an optical system having the antireflection film.SOLUTION: The antireflection film comprises layers stacked on a substrate. The layers are, successively from the substrate side, a first layer, a second layer, a third layer, a fourth layer and a fifth layer. Under the condition of a reference wavelength λ set to 550 nm, refractive indices and optical film thicknesses of the above layers satisfy ns>n1, 1.6≤ns≤2.05, 1.3≤n1≤1.8 and 0.018λ≤d1≤0.200λ, 1.8≤n2≤2.2 and 0.018λ≤d2≤0.11λ, 1.3≤n3≤1.8 and 0.04λ≤d3≤0.31λ, 1.8≤n4≤2.2 and 0.018λ≤d4≤0.15λ, and 1.2≤n5≤1.3 and 0.18λ≤d5≤0.33λ. |
