| 摘要 |
PURPOSE:To obtain a fingerprint picture faithful to an actual fingerprint by providing an optical correcting member to correct a component parallel to the optical axis of the whole optical path length from a fingerprint detecting plane to the main point of a lens so as to be approximately equal to the optical path length on the optical axis between a fingerprint detecting member and the lens. CONSTITUTION:A correcting prism 8 makes all the light reflected at the any spot of a fingerprint detecting plane 2 trace equal distance and reach a main point K of the front side of a lens 11. All the light reflected at the fingerprint plane 2 reaches the main point K of the lens 11 with equal optical path length with passing through the correcting prism 8. Accordingly, actual fingerprints on the fingerprint detecting plane 2 are image-formed as a fingerprint picture on a CCD light receiving plane 12 at an equal magnification without relation with parts and the generation of magnification difference in the fingerprint picture is prevented. Thus, the fingerprint picture faithful to the actual fingerprints can be obtained. |
