IDENTIFICATION CARD AND READING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To prepare an identification card comparatively inexpensive, to enable a lot of users to use that card and further to eliminate the danger of forgery. SOLUTION: This identification card 10 has a pattern 13 formed from sand blast at one part of one side at least. This identification card 10 is read by irradiating the pattern 13 with light, detecting reflected light through a photodetecting means and converting it to an electric signal. More concretely, an interference pattern generated by the phase difference between the reflected light of laser light irradiating the pattern 13 and reference light directly reflecting the laser light on a mirror is photodetected by a CCD camera and converted to the electric signal or the part of the pattern is irradiated with laser light and the reflected light is photodetected by the CCD camera and converted to the electric signal while moving the card. Then, such a method for performing the Fourier transformation of these electric signals and providing a spectrum distribution is preferably adopted.