Abstract: An optical member includes a light guide. An inclination angle of a first reflecting surface of the light guide with respect to a first direction perpendicular to a normal direction of the first reflecting surface is defined as ?r in a rotational direction about an axis extending in the normal direction. A line segment is defined by connecting the viewer and the light guide in a cross section perpendicular to the first direction. An inclination angle of the line segment with respect to a second direction perpendicular to the normal direction and the first direction is defined as ? in a rotational direction about an axis extending in the first direction. The first reflecting surface is formed so as to satisfy Inequation of 10°?arctan(tan ?r×sin ?)?90°.

Abstract: A blind spot assist device includes a first optical element and a second optical element. The first optical element reflects a part of incident light having a first angle of incidence at different second angles such that light is incident at the first angle on the first optical element from an outdoor view and reflected at the second angles on the first optical element. The second optical element is positioned to face the first optical element and reflects incident lights having different angles of incidence at a third angle such that lights reflected by the first optical element are incident at the second angles on the second optical element and reflected at the third angle on the second optical element toward a user.

Abstract: A virtual image display device displays a virtual image by projecting a display light of an image toward a projection unit, and includes: a display unit configured to emit the display light; and a diffraction reflection element configured to reflect the display light emitted from the display unit by diffraction. The diffraction reflection element has a plate shape along a horizontal plane. The diffraction reflection element is configured to emit the display light toward the projection unit arranged above the diffraction reflection element when the display light is incident, and is set such that an angle of incidence on the diffraction reflection element is larger than an angle of emission from the diffraction reflection element.