[OPTICAL REVIEW Vol. 10, No. 4 (2003) 175-178]
© 2003 The Optical Society of Japan

Shift-tolerance Property of Optical Security System using Phase-based Virtual Image

Dong-Hoan SEO* and Soo-Joong KIM

School of Electrical Engineering & Computer Science, Kyungpook National University, Daegu, 702-701, South Korea

(Received December 9, 2002; Accepted April 9, 2003)

The shift-tolerance property of the encrypted image or the Fourier decrypting key in the Fourier space is proposed based on a phase-encoded virtual image. The encrypted data is obtained by the Fourier transform of the product of a phase-encoded virtual image to camouflage the original one and a random phase image. Therefore, even if unauthorized users analyze the encrypted image, they cannot reconstruct the required image. This virtual image protects the original one from being counterfeited and from unauthorized access. We demonstrate the robustness to data loss and shift of the encrypted data or the Fourier decrypting key in the proposed decryption technique using an interferometer.

Key words: optical security system, random phase encoding, optical correlators

*E-mail address: dhseo@palgong.knu.ac.kr