| 摘要 |
PURPOSE:To obtain information on a ruggedness pattern which has a good contrast, no blur due to aberration by using a hologram with a thick film as a hologram so as to narrow a Bragg angle margin. CONSTITUTION:The rising line width of a human fingerprint is said to be about 150-600mum. The detector changes the angle width thetah of light contributing to connection among light beams scattered at a point 6 in a finger. If the aberration (blur) 6a observed at that time is below half the minimum value, 150mum, of the rising line, the rising line does not overlap with an adjacent rising line and an image is visible. Light quantity contributing to the connection is assumed to be within the Bragg angle margin thetah. If the optical path length of scattering light beams 91-93 is assumed to be (l), and the incident angle at the time of the highest efficiency to be thetah, information on a clear projecting part with few blurs due to the aberration can be obtained as the thetah becomes narrow.
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