| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method and apparatus capable of noncontactly detecting the thickness of a paper sheet such as a bank note or noncontactly inspecting whether or not a foreign object such as tape etc. is placed on a bank note. <P>SOLUTION: Terahertz light 12 is used to noncontactly inspect the thickness of a bank note 14. For the terahertz light 12, the wavelength to be used is a fraction of one to several times the thickness of the bank note 14. The terahertz light 12 is irradiated from one side 141 of the bank note 14, and reflected terahertz lights 121, 124 reflected from the front surface 141 and the back surface 142 of the bank note 14 are detected. The detected reflected terahertz light has a phase difference as the detected light contains the reflected light 121 reflected from the front surface and the reflected light 124 reflected from the back surface. The phase difference can be detected as the intensity of interference. As a result, the thickness of the bank note can be correctly and noncontactly detected. <P>COPYRIGHT: (C)2010,JPO&INPIT |
