| 摘要 |
PURPOSE:To attain the even irradiation of light by providing an optical prism of a prismatic shape having three faces to photograph the reflected light of the 1st face through the 3rd face and to make the dispersed illumination beams incident on the 2nd face. CONSTITUTION:A finger F touches a 1st face (acdf) of an optical prism 10 and at the same time the light of a light source 20 is made incident through a 2nd face (abc). Under such conditions, the light of only a part where the projecting part of the F touches reaches a 3rd face (bcef) of the prism 10. Thus a fingerprint picture is photographed to the 3rd face via a TV camera 30. In this case, the light intensity varies according to the recessing/projecting parts of the F and the light is dispersed through the 2nd face and made incident on the prism 10. As a result, the light produced from the recess part of the F is liable to travel toward the 1st face and equalized regardless of the recessing/projecting parts of the finger surface. Thus the camera 30 can photograph the F through the 3rd face with even illumination of the light. |
