Head-up display and vehicle

A head-up display comprising:

• a display device having a display surface for displaying an image;
• and
• a projection optical system for projecting an image displayed on the display surface onto a viewing area for an observer,
• wherein the projection optical system includes a first reflective element and a second reflective element in order along an optical path from the display surface to the viewing area,
• wherein a reflective surface of at least one of the first reflective element and the second reflective element has a concave shape,
• a light beam that is emitted from a center of the display surface and reaches a center of the viewing area is referred to as a reference light beam,
• an intersection of the reference light beam with the reflective surface of the first reflective element is referred to as a reference intersection point,
• a plane including the reference light beam incident on the first reflective element and the reference light beam reflected by the first reflective element is referred to as a reference plane,
• an intersection line of the reflective surface of the first reflective element with the reference plane is referred to as a reference intersection line,
• a tangent plane of the reflective surface of the first reflective element at the reference intersection point is referred to as a reference tangent plane,
• respective heights from two points, a vertically upper point and a vertically lower point, which are equidistant from the reference intersection point on the reference tangent plane, to the reflective surface of the first reflective element are referred to as a sag, and
• when perpendiculars extending from the two points, the vertically upper point and the vertically lower point, and normal to the reference tangent plane intersect with the reference intersection line, a sag at the vertically upper point is greater than a sag at the vertically lower point.