T. Nishi, J. Kobayashi and S. Komatsu: Personal Identification Making Use of a Stack of Light Source Arrays as a Key (Optics Japan 2005), 410-411.

We propose a new method of personal identification that makes use of a stack of light soruce arrays as a key. Three-dimensional arrangement of the light soruces is used as key information and the sorces are hidden within slits in order to make forgery difficult and to ensure high security. For extracting key information we use an imaging system consisting of a concave mirror and an array of light detectors. The feasibilty of the present method was confirmed by experiments.