A deterministic phase-encoded encryption system, which adopts a lenticular lens array (LLA) sheet as a phase modulator
(key), based on arbitrary two-step phase-shift interferometry (PSI), with an unknown phase step, is presented. The
principle of encryption and decryption which is using a LLA in arbitrary unknown two-step PSI is given. With the aid of
key holograms (right key), it can be theoretically shown that only the reconstructed object wavefront term will be left in
the image plane, and all the accompany undesired terms be eliminated. Thus the hidden information of object wavefront
in this encryption system can be numerically and successfully decrypted using arbitrary unknown two-step PSI with right
key. For comparisons, computer simulations are carried out to verify the principle of encryption and decryption without
key, with wrong key and with right key, respectively.
This work presents the working principle for digital holography with arbitrary phase-step reconstruction using multiple
holograms. The arbitrary phase-step of the reference wave can be easily estimated with two different approaches -blind
searching algorithm (Meng et al.) and the limited area algorithm (Hsieh et al.). Using these approximations, the
magnitude-contrast images are reconstructed without dc term and twin-image blurring, but the phase-contrast images are
filled with phase distortion. Computer simulations are carried out to verify the proposed approach and optical
experiments are performed to validate it. The optical results and spatial resolutions using different estimation of the
phase-step are presented and discussed herein.