Optical image coding with a circular Dammann grating

Doh, Kyu B.; Dobson, Kelly; Poon, Ting‐Chung; Chung, Philip

doi:10.1364/ao.48.000134

Cited by 13 publications

(9 citation statements)

References 20 publications

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“…For example, the latter can be integrated with existing image encryption schemes, such as [2][3][4][5][6][7][8] to foster stronger resistance of optical images towards illegal access and attacks. It is also possible to complement our proposed method with optical encryption [26], to prevent brute force decryption with numerical means. This is essential as the emergence of powerful hardware, such as the graphic processing unit (GPU), has enabled a massive amount of computation to be conducted in a parallel fashion.…”

Section: Resultsmentioning

confidence: 99%

Fast numerical generation and encryption of computer-generated Fresnel holograms

2010

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In the past two decades, generation and encryption of holographic images have been identified as two important areas of investigation in digital holography. The integration of these two technologies has enabled images to be encrypted with more dimensions of freedom on top of simply employing the encryption keys. Despite the moderate success attained to date, and the rapid advancement of computing technology in recent years, the heavy computation load involved in these two processes remains a major bottleneck in the evolution of the digital holography technology. To alleviate this problem, we have proposed a fast and economical solution which is capable of generating, and at the same time encrypting, holograms with numerical means. In our method, the hologram formation mechanism is decomposed into a pair of onedimensional (1D) processes. In the first stage, a given three-dimensional (3D) scene is partitioned into a stack of uniformed spaced horizontal planes and converted into a set of hologram sublines. Next, the sublines are expanded to a hologram by convolving it with a 1D reference signal. To encrypt the hologram, the reference signal is first convolved with a key function in the form of a maximum length sequence (also known as MLS, or M-sequence). The use of a MLS has two advantages. First, an MLS is spectrally flat so that it will not jeopardize the frequency spectrum of the hologram. Second, the autocorrelation function of an MLS is close to a train of Kronecker delta function. As a result, the encrypted hologram can be decoded by correlating it with the same key that is adopted in the encoding process. Experimental results reveal that the proposed method can be applied to generate and encrypt holograms with a small number of computations. In addition, the encrypted hologram can be decoded and reconstructed to the original 3D scene with good fidelity.

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Section: Resultsmentioning

confidence: 99%

Fast numerical generation and encryption of computer-generated Fresnel holograms

2010

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“…This is advantageous because any imperfection in the optical system, such as aberration, can be alleviated in practice. In contrast to the previous intensity-based coding method [3], which can only code the image at the focal plane, the proposed method can be used for complex coding of a 3D object.…”

Section: Discussionmentioning

confidence: 99%

“…We propose to perform 3D optical image encryption with a circular Dammann grating (CDG) through the use of OSH. In contrast to a recent intensity-based optical system based on the grating for two-dimensional (2D) image coding [3], the present coding method is complex-amplitude based and is suitable for 3D image coding. Because the Dammann grating can be easily fabricated and duplicated, decryption will be easier than those encoded with a random phase mask [4,5].…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional complex image coding using a circular Dammann grating

et al. 2010

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Recently, optical image coding using a circular Dammann grating (CDG) has been proposed and investigated. However, the proposed technique is intensity based and could not be used for three-dimensional (3D) image coding. In this paper, we investigate an optical image coding technique that is complexamplitude based. The system can be used for 3D image coding. The complex-amplitude coding is provided by a circular Dammann grating through the use of a digital holographic recording technique called optical scanning holography. To decode the image, along the depth we record a series of pinhole holograms coded by the CDG. The decoded reconstruction of each depth location is extracted by the measured pinhole hologram matched to the desired depth. Computer simulations as well as experimental results are provided.

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“…It has been used in optical image coding [17]. Usually, the optical behavior of a circular Dammann grating is addressed in polar coordinates.…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional profilometry using a Dammann grating

2009

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We propose three-dimensional (3D) profilometry based on a Fourier transform in which a twodimensional (2D) Dammann grating and a cylindrical lens are used to generate structured light. The Dammann grating splits most of the illumination power into a 2D diffractive spot matrix. The cylindrical lens transforms these 2D diffractive spots into one-dimensional fringe lines that are projected on an object. The produced projection fringes have the advantages of high brightness and high contrast and compression ratios. The experiments have verified the proposed 3D profilometry. The 3D profilometry using Dammann grating should be of high interest for practical applications.

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Optical image coding with a circular Dammann grating

Cited by 13 publications

References 20 publications

Fast numerical generation and encryption of computer-generated Fresnel holograms

Fast numerical generation and encryption of computer-generated Fresnel holograms

Three-dimensional complex image coding using a circular Dammann grating

Three-dimensional profilometry using a Dammann grating

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