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Browsing by Author "Sheridan, John T."

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Digital computation of the complex linear canonical transform

Liu, Changgeng ; Wang, Dayong ; Healy, John J. ; Hennelly, Bryan M. ; Sheridan, John T. ; Kim, Myung K. (Optical Society of America, 2011-07-01)

An efficient algorithm for the accurate computation of the linear canonical transform with complex transform parameters and with complex output variable is presented. Sampling issues are discussed and the requirements for ...
Dual wavelength digital holographic Laplacian reconstruction

Ryle, James P. ; Li, Dayan ; Sheridan, John T. (Optical Society of America, 2010-09-15)

Access to the spatial derivatives of an optical wave field can be used to enhance edge detection, focusing, and holographic imaging. It was recently shown that, by using digital holographic techniques, the Laplacian of an ...
Effects of absorption and inhibition during grating formation in photopolymer materials

Gleeson, M. R. ; Kelly, John V. ; Close, Ciara E. ; O'Neill, Feidhlim T. ; Sheridan, John T. (Optical Society of America, 2006-10-01)

Photopolymer materials are practical materials for use as holographic recording media, as they are inexpensive and self-processing (dry processed). Understanding the photochemical mechanisms present during recording in ...
Examination of the photoinitiation processes in photopolymer materials

Gleeson, M. R. ; Liu, Shui ; O'Duill, Sean ; Sheridan, John T. (American Institute of Physics, 2008-09)

Holographic data storage requires multiple sequential short exposures. However, the complete exposure schedule may not necessarily occur over a short time interval. Therefore, knowledge of the temporally varying absorptive ...
Extended model of the photoinitiation mechanisms in photopolymer materials

Liu, Shui ; Gleeson, M. R. ; Sabol, Dušan ; Sheridan, John T. (American Institute of Physics, 2009-11)

In order to further improve photopolymer materials for applications such as data storage, a deeper understanding of the photochemical mechanisms which are present during the formation of holographic gratings has become ...
Fast linear canonical transforms

Healy, John J. ; Sheridan, John T. (Optical Society of America, 2010-01-01)

The linear canonical transform provides a mathematical model of paraxial propagation though quadratic phase systems. We review the literature on numerical approximation of this transform, including discretization, sampling, ...
Fast numerical algorithm for the linear canonical transform

Hennelly, Bryan M. ; Sheridan, John T. (Optical Society of America, 2005-05-01)

The linear canonical transform (LCT) describes the effect of any quadratic phase system (QPS) on an input optical wave ﬁeld. Special cases of the LCT include the fractional Fourier transform (FRT), the Fourier transform ...
Fundamental diffraction limitations in a paraxial 4-f imaging system with coherent and incoherent illumination

Kelly, Damien P. ; Sheridan, John T. ; Rhodes, William T. (Optical Society of America, 2007-07-01)

In the usual model of an imaging system, only the effects of the aperture stop are considered in determining diffraction-limited system performance. In fact, diffraction at other stops—those associated with different lens ...
Generalization of the boundary diffraction method for volume gratings

Sheridan, John T. (Optical Society of America, 1994-02-01)

The boundary diffraction method (BDM) is an approximate method that permits the derivation of analytic solutions for the output beams, both forward and backward propagating, that arise from the fundamental nature of ...
Generalization of the boundary diffraction method for volume gratings

Sheridan, John T. (Optical Society of America, 1994-02-01)

The boundary diffraction method (BDM) is an approximate method that permits the derivation of analytic solutions for the output beams, both forward and backward propagating, that arise from the fundamental nature of ...
Generalized in-line digital holographic technique based on intensity measurements at two different planes

Situ, Guohai ; Ryle, James P. ; Gopinathan, Unnikrishnan ; Sheridan, John T. (Optical Society of America, 2008-02-10)

In-line digital holography based on two-intensity measurements [Zhang et al. Opt. Lett. 29, 1787 (2004)], is modiﬁed by introducing a π shifting in the reference phase. Such an improvement avoids the assumption that the ...
Generalized model of photopolymer behavior for use in optimized holographic data storage scheduling algorithms

Kelly, John V. ; Gleeson, M. R. ; Close, Ciara E. ; O'Neill, Feidhlim T. ; Sheridan, John T. (Optical Society of America, 2006-10-10)

A generalized model of photo-polymerization in free radical chainforming polymers has been developed. Applying this model to data storage, optimized scheduling algorithms are developed for the multiplexing of multiple ...
Generalized Yamaguchi correlation factor for coherent quadratic phase speckle metrology systems with an aperture

Kelly, Damien P. ; Ward, Jennifer E. ; Gopinathan, Unnikrishnan ; Hennelly, Bryan M. ; O'Neill, Feidhlim T. ; Sheridan, John T. (Optical Society of America, 2006-12-01)

In speckle-based metrology systems, a finite range of possible motion or deformation can be measured. When coherent imaging systems with a single limiting aperture are used in speckle metrology, the observed decorrelation effects ...
Generalizing, optimizing, and inventing numerical algorithms for the fractional Fourier, Fresnel, and linear canonical transforms

Hennelly, Bryan M. ; Sheridan, John T. (Optical Society of America, 2005-05-01)

By use of matrix-based techniques it is shown how the space–bandwidth product (SBP) of a signal, as indicated by the location of the signal energy in the Wigner distribution function, can be tracked through any quadraticphase ...
Holographic data storage : optimized scheduling using the nonlocal polymerization-driven diffusion model

Sheridan, John T. ; O'Neill, Feidhlim T. ; Kelly, John V. (Optical Society of America, 2004-08-01)

The choice of an exposure schedule that maximizes the uniformity and capacity of a holographic recording medium is of critical importance in ensuring the optimum performance of any potential holographic data storage scheme. ...
Holographic grating evolution in photopolymer materials

Gleeson, M. R. ; Kelly, John V. ; Close, Ciara E. ; Sabol, Dušan ; Sheridan, John T. (Optical Society of America, 2007-05-20)

A generalized non-local polymerization driven diffusion (NPDD) model is presented, including the effects of absorption and inhibition. Experimentally obtained growth curves are fit using a four-harmonic numerical fitting ...
Holographic interferometry and the fractional Fourier transformation

Sheridan, John T. ; Patten, Robert (Optical Society of America, 2000-04-01)

The fractional Fourier transform (FRT) is shown to be of potential use in analyzing the motion of a surface by use of holographic interferometry. The extra degree of freedom made available by the use of the FRT allows ...
Holographic photopolymer materials : nonlocal polymerization-driven diffusion under nonideal kinetic conditions

Kelly, John V. ; O'Neill, Feidhlim T. ; Sheridan, John T. ; Neipp, Cristian ; Gallego, Sergi ; Ortuño, M. (Optical Society of America, 2005-02-01)

The kinetics of photosensitive polymer holographic recording materials are examined assuming a material that exhibits nonideal kinetic behavior. Previously, a linear relationship between monomer concentration and polymerization ...
Holography and photopolymer recording materials

Sheridan, John T. (Optical Society of America, 2010-04-11)

Photopolymers act as drivers and enabler of fabrication technologies for applications including refractive/diffractive optical elements, hybrid 3D optoelectronic circuitry, data storage recoding media and self-trapping. ...
Holography : an interpretation from the phase-space point of view

Situ, Guohai ; Sheridan, John T. (Optical Society of America, 2007-12-15)

The formation of holograms is interpreted as the consequence of the bilinearity of the ambiguity function. Reconstruction can then be regarded as the manipulation of the ambiguity function. Specifically, we show that in ...