| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide hard-to-fabricate forgery-proof sheets such as a gift certificate, a stock certificate or various kinds of cards, the judgement of genuineness of which is certain. SOLUTION: A plurality of fine permeable holes 6a to 6d obtained by dividing a specific shape such as a figure, a character or a symbol, are formed by dispersing the holes 6a to 6d to the four corners of the sheet through irradiating the sheet such as a gift certificate with a laser beam in different directions. It is determined whether a light is transmitted at the same angle and in the same direction as a laser irradiation angle and a laser irradiation direction when each of the through holes 6a to 6d are formed. When the light does not pass through the holes 6a to 6d, the sheet is judged as forged. Further, when the light passes through the holes 6a to 6d, the light passing through each of the holes 6a to 6d is synthesized and when the synthesized shape coincides with the divided specific shape, the sheet is judged as genuine.</p> |
