| 摘要 |
PURPOSE:To obtain a Fresnel lens having a good light condensing efficiency, by providing refracting bodies which refract rays of light reflected by a surface of total refraction in the direction of focal point at the high refractive index areas around the central part of the Fresnel lens. CONSTITUTION:Small lens bodies 2 of an ordinary Fresnel lens are continuously provided at the central part of this lens which is low in refractive index and refracting bodies 3 are continuously provided at the peripheral area of the central part which is high in refractive index. When rays of light are vertically made incident on the face (a) of the refracting body 3, all of the incident rays of light are reflected by the face (c) of the body 3 and the emitted rays of light are condensed to the focal point of the small lens bodies 2. Therefore, all of the incident rays of light are condensed to the focal point and the light condensing efficiency of this Fresnel lens 1 is improved.
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