ILLUMINATION DEVICE

摘要

An optical element according to the present invention is provided with: an incident surface that covers a light-emitting surface of a planar light source; a reflection surface disposed at a position facing the incident surface; and an exit surface that is connected to the peripheral edge of the reflection surface. The center of the light-emitting surface is a point (O). An axis that passes through the point (O) and is perpendicular to the light-emitting surface is the optical axis of the optical element. The reflection surface of the optical element has a recessed shape in the vicinity of the optical axis with respect to the peripheral edge. In an arbitrary cross section of the optical element that includes the optical axis and is perpendicular to the light-emitting surface, at least 80% of the area of the reflection surface reflects light irradiated from the point (O). The incline of the incident surface with respect to a first surface is set so as to satisfy the following equations, where ?p is the incline with respect to the first surface of the normal line of the incident surface at a point (P) at which the incident surface intersects with the first surface including the light-emitting surface, ? is the incline with respect to the first surface of a straight line that connects the point (P) with a point at which the reflection surface and the exit surface intersect, and n is the refractive index of the material of the optical element.