| 摘要 |
An illuminating device includes a light source and a light receiving surface, first and second light exit surfaces. When a point at the edge of the light emitting surface is P2 and an axis which passes through a center P1 of a light emitting surface and is perpendicular to the light emitting surface is an optical axis, the optical element has a hollow around the optical axis. The first light exit surface is such that x coordinate of a point most distant from the optical axis on the first light exit surface is at least 1.5 times x coordinate of P2, that in 80% or more of an area in which x coordinate of a point is at least the x coordinate of another point P3, an angle of incidence of light emitted at P1 is at least the critical angle and that in 80% or more of an area in which x coordinate of a point is equal to or smaller than x coordinate of another point P4, an angle of incidence of light emitted at P2 is smaller than the critical angle.
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