高次複屈折を用いた情報セキュリティーデバイスの開発

摘要

We propose a new type of visual information security device (VISD) consists of higher-order birefringence elements. When a higher-order birefringence film which is sandwiched between a pair of polarizer is illuminated by white light from one side, the image with white color is observed. On the other hand, when the film is illuminated by monochromatic light, the brightness of transmitted light depends on its wavelength. The VISD is fabricated by controlling the amount of higher order birefringence which gives a high contrast at the only certain wavelength under polarized illumination. The device can be decoded by the illumination of specific reading wavelength. In this paper, we have simulated and demonstrated observation images of the device under white and monochromatic illuminations. Furthermore, stored information can be easily distributed to multiple physical keys which show arbitrary images. In this case, since the image is decoded by XOR operation of each pixel of physical keys, the decoded result is obtained by superimposing them.