Abstract: An extreme ultraviolet light condensation mirror includes: a substrate; a multi-layer reflective film on the substrate and configured to reflect extreme ultraviolet light having a wavelength of 13.5 nm; and a protective film on the multi-layer reflective film. The protective film includes an oxide silicon layer on the multi-layer reflective film and a titanium oxide layer on the oxide silicon layer having one surface exposed. When x represents the thickness of the titanium oxide layer, the phase of standing wave of the extreme ultraviolet light at the position of the one surface for the maximum reflectance of the extreme ultraviolet light is defined to be zero, and a direction from the one surface toward the multi-layer reflective film is defined to be negative, the position of the one surface is a position at which the phase y of standing wave satisfies the expression below. ?0.313x3+1.44x2+2.57x?51.0?y<0.

Abstract: An extreme ultraviolet light condensation mirror includes: a substrate; a multi-layer reflective film on the substrate and configured to reflect extreme ultraviolet light having a wavelength of 13.5 nm; and a protective film on the multi-layer reflective film. The protective film includes an oxide silicon layer on the multi-layer reflective film and a titanium oxide layer on the oxide silicon layer having one surface exposed. When x represents the thickness of the titanium oxide layer, the phase of standing wave of the extreme ultraviolet light at the position of the one surface for the maximum reflectance of the extreme ultraviolet light is defined to be zero, and a direction from the one surface toward the multi-layer reflective film is defined to be negative, the position of the one surface is a position at which the phase y of standing wave satisfies the expression below. ?0.313x3+1.44x2+2.57x?51.