Optical element, optical system, image pickup apparatus, and optical apparatus

An optical element comprising:

• a substrate;
• and
• an antireflection film,
• wherein the antireflection film consists of a first layer formed on an optical surface of the substrate, and a second layer formed on the first layer,
• wherein the first layer includes a first organic compound,
• wherein the second layer includes a second organic compound, and
• wherein the following inequalities are satisfied:
• 1.30≤n1≤1.70
• 1.10≤n2≤1.26
• −0.2≤(ns−1)−2(n1−n2)≤0.2
• 100≤n1d1c≤155
• 100≤n2d2c≤155
• 100≤n1d1q≤155
• 100≤n2d2q≤155
• 1.0<d1q/d1c≤1.3
• 1.0<d2q/d2c≤1.3
• where ns is a refractive index of the substrate at a wavelength of 550 nm, n1 is a refractive index of the first layer at a wavelength of 550 nm, n2 is a refractive index of the second layer at a wavelength of 550 nm, d1c (nm) is a physical film thickness of the first layer on an optical axis, d2c (nm) is a physical film thickness of the second layer on the optical axis, d1q (nm) is a physical film thickness of the first layer at a most distant position from the optical axis in an effective area of the optical surface, and d2q (nm) is a physical film thickness of the second layer at a most distant position from the optical axis in the effective area of the optical surface.