| 摘要 |
<p>A card true/false decision apparatus comprises a measuring light projection system (23) for projecting a measuring beam P from a predetermined direction to a hologram (2) provided at a predetermined position on a card (1), a photodetector element (24b) for receiving the reflected/diffracted light R1, R2, and R3 of the measuring beam P reflected by the hologram (2), averaging means (25) for changing the radiation position of the measuring beam P on the hologram 2 so as to average photodetector signals corresponding to the light quantity distribution on the photodetector element (24b), and decision means (26) for comparing the output of the averaging means with an allowance value so as to determine whether the card is true or false.</p> |
