| 摘要 |
PROBLEM TO BE SOLVED: To provide an antireflection structure having high antireflection effect at a low cost by using a metal thin film having a complex refractive index with a specified refractive index and a specified absorption coefft. to constitute the antireflection film. SOLUTION: This antireflection structure prevents reflection from the back face 10b of a transparent substrate 10. The transparent substrate 10 consists of a transparent glass or transparent plastics (acryl resin, polycarbonate or the like). On the back face 10b of the transparent substrate 10, a metal thin film 22 is formed by sputtering or the like in a specified uniform film state or an island-like film having specified thickness. The optical const. of the metal thin film 22 is expressed by the formula of N=n'-lk. wherein N is the complex refractive index, n' is the refractive index and (k) is the absorption coefft. A metal having 2.0 to 4.0 refractive index n' and weak absorption of 2.0 to 4.0 absorption coefft. is preferably used, and for example, Ti, Cr, Ni. Ni-Cr alloy, stainless steel or the like is used. The metal thin film 22 is preferably formed to about 20 to 30 Å thickness. |
