This research proposes a method that uses a single object beam to record multiple images in a photorefractive crystal medium without having to use any reference wave. The object beam in this study is modulated using a lenticular lens array sheet to produce a set of sub-object beams. These beams are then angularly separated on the recording plane and their scattered waves overlapped in an iron-doped photorefractive LiNbO₃ crystal. This single-exposure, multiple-holographic-recording method is simple and proven successful via the experiments that recorded four holograms in a 30 x 1 mm³ LiNbO₃:Fe crystal with single exposure.
A deterministic phase-encoded encryption system is proposed. A lenticular lens array (LLA) sheet with a particular LPI (lenticular per inch) number is chosen as a modulator (key) instead of the random phase molator. The suggested encryption scheme is based on arbitrary two-step phase-shift interferometry (PSI), using an unknown phase step. The encryption and decryption principle is based on an LLA in arbitrary unknown two-step PSI. Right key holograms can be used to theoretically show that the object wavefront is the only one left in the hologram plane and that all accompanying undesired terms are eliminated. The encrypted image can therefore be numerically and successfully decrypted with the right key in the image plane. The number of degrees of freedom of the encryption scheme increases with the distance from the object and the LLA to the CCD, and also with the unknown phase-step and the LLA LPI number. Computer simulations are performed to verify the encryption and decryption principles without a key, with the wrong key and with the right key. Optical experiments are also performed to validate them
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