The diffraction of light by high frequency sound waves: Part I.

Polymer films with embedded liquid crystal inclusions (polymer-dispersed liquid crystals) are superb composites for addressable windows, flexible displays and optical storage. Their scattering behavior and electro-optic properties depend essentially on the shape and size of the liquid crystal inclusions, which are typically formed by phase separation from a multicomponent homogeneous mixture. Here, pulsed field gradient NMR is used to measure the self-diffusion coefficients of the liquid crystal and a photo-reactive monomer, which compose such a precursor mixture. The kinetics of holographic grating formation in this mixture can be predicted by inserting the NMR diffusion coefficient of the monomer and the polymerization rate in a reaction diffusion model. The ratio of diffusion rate over reaction rate is found to be in the limiting regime in which the kinetics of the grating formation is not sensitive to this parameter.

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“…If Q≪ 1, the diffraction efficiency can be calculated by using the Raman-Nath theory for thin gratings [19]:…”

Section: Resultsmentioning

confidence: 99%

Kinetics of the grating formation in holographic polymer-dispersed liquid crystals: NMR measurement of diffusion coefficients

et al. 2012

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“…We assume that the signal beam consists of many ''individual beams'', which illuminate the photopolymer at different incident angles. For each ''individual beam'', in the Raman-Nath regime [20,21], the maxima of the intensity occur in the directions that when projected on the x-z plane make angles, denoted by y xk , with the x-axis (Fig. 7):…”

Section: Discussionmentioning

confidence: 99%

Two-dimensional higher-diffraction-order optical beam splitter based on phenanthrenequinone-doped poly(methyl methacrylate) photopolymer

Gong

Zhou

Liu

et al. 2009

Optics and Lasers in Engineering

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“…This imaging method provides an intensity distribution over the CCD array that is approximately an affine function of the phase in plane p 0 . We neglect Doppler shifting of the optical frequency because of the motion of the ultrasound pulse [12]- [16]. We also assume that only the phase of the optical wave is altered during its passage through the sound field.…”

Section: Phase Contrast Methodmentioning

confidence: 99%

“…After a number of attempts by prominent contemporary scientists, Raman and Nath presented the first accurate model of the physics involved in optical scattering 1 by a narrowband ultrasound field in a series of papers published in 1935 and 1936 [12]- [16]. Since then, the majority of the research in this area has focused on deduction of narrowband beam cross-sectional power or amplitude from farfield measurements of scattered optical intensity.…”

Section: Introductionmentioning

confidence: 99%

Optical measurement of ultrasonic Poynting and velocity vector fields

Pitts

2002

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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This report describes a method for estimating several wide bandwidth ultrasonic field parameters from optical measurements of the local, acoustically induced, refractive index perturbation in water. These parameters include Poynting and particle velocity vector fields as well as pressure and density fields at any temporal delay under mild (forward-propagating) assumptions on the angular plane-wave spectrum of the ultrasound field. A sampling theorem is derived stating that two complete measurements of the three-dimensional pressure field separated in time by ∆t allow release of the forward-propagating assumption for every acoustic wave number k satisfying k 6 = n =(c∆t), where c is the acoustic wave speed in the medium and n an integer greater than zero. The approach provides detailed measurements of very general ultrasound fields.Two optical measurement methods that acquire the Radon transform of the three-dimensional refractive index perturbation are briefly reviewed. It is shown that the Radon transform of the field itself satisfies a twodimensional wave equation and may be propagated independently forward or backward in time under a source-free model. Conversely, the Radon transform of the ultrasound field measurement at several known time delays provides a means of applying a filter to the data based on known ultrasound propagation models. Each two-dimensional distribution may be propagated to a common time point and the ensemble averaged, thus incorporating the propagation model into the measurement. We support the presented theory with several experiments.

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The diffraction of light by high frequency sound waves: Part I.

Cited by 419 publications

References 2 publications

Kinetics of the grating formation in holographic polymer-dispersed liquid crystals: NMR measurement of diffusion coefficients

Kinetics of the grating formation in holographic polymer-dispersed liquid crystals: NMR measurement of diffusion coefficients

Two-dimensional higher-diffraction-order optical beam splitter based on phenanthrenequinone-doped poly(methyl methacrylate) photopolymer

Optical measurement of ultrasonic Poynting and velocity vector fields

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