Patent ID: 8693099

Claim:
An antireflection film provided between a metal film having a complex refractive index represented by N M =n M −i·k m and a glass substrate having a refractive index N G , wherein the metal film is an exposed surface of the antireflection film and includes a metal film component selected from the group consisting of molybdenum and a nickel alloy, comprising, from the metal film side: (A) a first dielectric layer having a refractive index N 1 ; (B) a second dielectric layer provided on the first dielectric layer and having a refractive index N 2 ; and (C) a third dielectric layer provided on the second dielectric layer and having a refractive index N 3 , wherein N 1 <n M , N 1 >N G , N 2 <N G , and N 3 >N G hold, whereby light which is incident on the glass substrate and which reaches the metal film is prevented from being reflected by the metal film, and wherein 4.29≦N 1 +N 3 ≦4.75 holds.