| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical device which is constituted by combining a light emitting element array with an image forming optical system and can be improved light utilizing efficiency, by efficiently making light rays emitted from the light emitting elements of the array incident on the image forming optical system. SOLUTION: In an LED array 10, recessed sections 24 each having such a inverted truncated conical shape as the cocktail glass has are arranged on the surface of an n-type GaAs epitaxial layer 22 formed on a GaAs substrate 20. Side wall of each recessed section 24 which expands toward an opening of the section 24 formed on the surface of the epitaxial layer 22 from a bottom section of the section 24 from a slope 26 and the light emitting section 28 of an LED composed of a p-type GaAs layer is formed on the bottom of the section 24. Of the light radially emitted form the light emitting section 28, therefore, the light which falls within a prescribed radiation angle is directly made incident to an image forming optical system as direct light L1 and, at the same time, the other light which does not fall within the radiation angle is made incident on the slope 26 on the side wall of the section 24 and reflected by the slope 26. A reflected light L3 is made incident on the image forming optical system. |
