Patent ID: 7618161

Claim:
A lighting apparatus comprising: a light source which emits light rays; a Fresnel lens acting as a convex lens having a convergent function of converting the light rays to a spotlight and projecting the spotlight on an illumination area, which is made of a lens material whose refraction index is n, and projects light rays from the light source at a specified radiation view angle φ to the illumination area, and has an optical axis, the Fresnel lens comprising: a plurality of Fresnel lens segments which are arranged concentrically around a common optical axis, and are made into ridge shapes respectively, wherein each Fresnel lens segment includes: a segment lens surface which has a peak and a bottom corresponding to one and the other end of the segment lens surface, respectively, and is curved into a concave surface toward the illumination area in respect to a reference plane connecting the peak and the bottom, a rise surface which is arranged between adjacent lens surfaces, and extended between the peak and the bottom, the light rays projected from adjacent lens surfaces irradiating circular band areas having widths, respectively, which mutually overlap at least half of the width of the circular band area.