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Optical Engineering

Digital Fresnel field encryption for three-dimensional information security
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Paper Abstract

The complex Fresnel field that contains three-dimensional (3-D) information about an object can be retrieved from an optically generated and electronically detected single off-axis Fresnel hologram of a 3-D object. The retrieved complex Fresnel field gives the appearance of a noise-like distribution. This is primarily due to the scattering nature of the object and the resulting speckle noise, which is a salient trait of the reconstruction process of a hologram. We describe a possible method for securing holographic information by digital encoding of the Fresnel field. A single random-phase Fourier plane encoding is carried out with an assumption that the noisy nature of the complex field may be equivalent to the primary random mask-bonded field, as in the case of conventional double random-phase Fourier plane encoding. The analogy between the decryption process and the numerical reconstruction of the hologram leads to a single-step reconstruction of the complex object field from the encrypted Fresnel field, thus saving computational power. The use of a single off-axis hologram is helpful in zero-order and twin-image free reconstruction. The algorithm is explained with experimental results to support the proof of the concept.

Paper Details

Date Published: 1 April 2007
PDF: 8 pages
Opt. Eng. 46(4) 045801 doi: 10.1117/1.2727377
Published in: Optical Engineering Volume 46, Issue 4
Show Author Affiliations
Anith Nelleri, Indian Institute of Technology Delhi (India)
Joby Joseph, Indian Institute of Technology Delhi (India)
Kehar Singh, Indian Institute of Technology Delhi (India)

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