| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface light source device for surface inspection capable of emitting a precise parallel beam over a wide range, using light emitting diodes. SOLUTION: This surface light source device is provided with a light source 11 consisting of a light emitting diode group formed by arraying the plurality of light emitting diodes 11a depth-directionally circular-arc-likely to conform respective optical axes with the circular arc center, and a Fresnel lens 15 faced to the light source in front of the circular arc center, and using the circular arc center as a focal point. The Fresnel lens emits the irradiation beam in each of the light emitting diodes 11a passing the focal point along an optical axis face including the respective optical axes of the plurality of light emitting diodes 11a arrayed circular-arc-likely, in parallel along the optical axis face. The surface of an inspection object is thereby irradiated with the parallel beam to allow inspection of a micro defect on the surface by a reflection beam thereof. COPYRIGHT: (C)2005,JPO&NCIPI
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