A Novel Optical Image Encryption Technique using Single-beam Holographic Storage System

Description

The researchers propose a novel optical image encryption scheme using the single-beam holographic system which employs a spatial light modulator (SLM) to modulate both the object and reference beams. Holographic techniques have the advantages of varying a number of parameters, such as the wavelength, the angle of incidence, the phase and the polarization of the laser beam. In a conventional holography system, the two beam off-axis interference technique is normally used. However this system is limited by its complex optical path configuration and the maintenance of stricter stability between the object and reference paths. The single-beam (or collinear) holography system will provide simple optical paths and much more stable system with less demand for mechanical precision to achieve better optical interference pattern between the object and the reference beams. Through the use of the spatial light modulator which the researchers have designed many diffractive optical elements in previous research works, they can code the reference and object beams in various ways using the parameters described previously, generating high-capacity multi-image holograms which can be decrypted separately using predetermined reference beam masks as the “decoding” keys. This technique should have good potential and useful applications in high-capacity holographic optical storage and in anti-counterfeiting measures used in consumer product labeling system, such as credit card logos, etc.