摘要 |
<p>Detecting counterfeit banknotes is achieved by directing ultraviolet light at a sample from a source (104) and measuring the level of ultraviolet light reflected from the sample using a first photocell (105) and the amount of fluorescent light generated by the sample using a second photocell (106). The detected levels are compared with reference levels and only if both reflective and fluorescent criteria are satisfied is the note declared genuine. The sample, during test, is swiped over a glass window (102), preferably under an overlying shield.</p> |