Optical element, window material, fitting, and insolation shielding device

摘要

An optical element has a first optical layer; a reflective layer; and a second optical layer. The reflective layer includes at least five layers of high refractive-index layers and metal layers alternately laminated. When a thickness L of the entire reflective layer is 80 nm, a ratio ± of an optical thickness of the entire metal layers to that of the entire high refractive-index layers and a ratio ² of an optical thickness of a third high refractive-index layer to that of a first high refractive-index layer are included in a first region, when the thickness L is 90 nm, the ratios ± and ² are included in a second region, and when the thickness L is 80 to 90 nm, the ratios ± and ² are included in a space enclosed by the first region, the second region, and straight lines derived from these regions.