I Digital Holography – Computer-Generated Holograms

Bryngdahl, Olof; Wyrowski, Frank

doi:10.1016/s0079-6638(08)70288-9

Cited by 122 publications

(60 citation statements)

References 103 publications

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“…Because computer-generated holograms (CGHs) can produce wavefronts with any desired amplitude and phase distributions, they have yielded many applications since Lohmann et al [17,18] firstly demonstrated it several decades ago, such as optical interconnection [19], spatial filtering [20], three-dimensional display [21,22], and holographic optical manipulation [23]. Two steps are needed for the production of a Fourier hologram.…”

Section: Realizing Optical Storage By Methods Of Computer-generated Homentioning

confidence: 99%

Several Diffractive Optical Elements Fabricated by Femtosecond Laser Pulses Writing Directly

Guo¹,

Ran²,

Qu³

et al. 2010

Coherence and Ultrashort Pulse Laser Emission

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Section: Realizing Optical Storage By Methods Of Computer-generated Homentioning

confidence: 99%

Several Diffractive Optical Elements Fabricated by Femtosecond Laser Pulses Writing Directly

Guo¹,

Ran²,

Qu³

et al. 2010

Coherence and Ultrashort Pulse Laser Emission

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“…The present security system can be viewed as a generalization of the Fresnel computer-generated hologram. In this analogy, h 2 (ξ, η) plays the role of a generalized medium between h 1 (ξ, η) and the reconstructed output image A(x, y) in a fashion similar to the quadratic phase factor representing the free-space medium in the Fresnel hologram reconstruction [14]. The medium function can be used as a lock to expose an image but does not contain any information on the image, and therefore its size does not limit the image capacity that can be utilized by the system.…”

Section: Synthesis Of a Key Mask In The Jtcmentioning

confidence: 99%

Steganography and Encryption Systems Based on Spatial Correlators with Meaningful Output Images

Rosen

Javidi

2005

Optical and Digital Techniques for Information Security

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Summary. Three different optical security systems are surveyed in this chapter. Their common feature is the appearance of meaningful images on the system's output. In the first system, two phase-only transparencies are placed in a 4f correlator such that a known output image is received. In the second system, two phase-only transparencies are placed together in a joint-transform correlator for the same purposes. In both cases, the two phase masks are designed with an iterative optimization algorithm with constraints in the input and the output domains. In addition to simple verification, these security systems are capable of identifying the type of input mask according to the corresponding output image it generates. The third system is different from the two others in the sense that the system's input signal also is a meaningful image. This last system can offer various solutions for steganography, watermarking, and information coding. This chapter summarizes research first published in [1-3]. IntroductionOptical technologies have recently been employed in data security [4][5][6][7]. Compared with traditional computer and electrical systems, optical technologies offer primarily two types of benefits. (1) Optical systems have an inherent capability for parallel processing; that is, rapid transmission of information. (2) Information can be hidden in any of several dimensions, such as phase or spatial frequency; that is, optical systems have excellent capability for encoding information.In several pioneering studies [4][5][6], the authors demonstrated different optical verification systems for information security applications based on optical correlations. These systems correlate two functions: one, the lock, is always inside the correlator, and the other, the key, is presented to the system by the user in the verification stage. Mostly, the systems determine whether the input is true or false by detecting the correlation peak in the output plane. The next generation of these security systems should offer a higher level of security and more sophisticated services than the simple verification offered by

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“…However, the creation of laser hologram requires relatively complex equipment. Computers have also been used to design laser holograms [28]. Traditional holograms have also been used together with interactive computer graphics [29].…”

Section: Introductionmentioning

confidence: 99%