Speckle decorrelation study of liquid diffusion

Ambrosini, Dario; Paoletti, Domenica; Ponticiello, A.; Spagnolo, Giuseppe Schirripa

doi:10.1016/s0143-8166(01)00118-x

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…where it is viewed coming in by the CCD matrix at the image point y . A relative displacement d proportional to the change of the ray deflection is observed, at two instances in time t 1 and t 2 [14,15]:…”

Section: Theoretical Backgroundmentioning

confidence: 98%

Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography

Leo

Paoletti

Ambrosini

2018

Eur. Phys. J. Appl. Phys.

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Interfacing two liquid mixtures in a diffusion cell induces noise in the initial state of the diffusing system, which produces a gap between the diffusion boundary and the ideally boundary assumed in the theory. Measured diffusivity values systematically drift with time and they are often corrected by using a linear shift of the zero-time of the process after sufficiently long time when the system reaches the free one-dimensional diffusion regime. In data analysis methods which involve optical correlation between pairs of successive digital images of the cell, it is not easy to establish how long the transient lasts. We show that when the initial perturbation between solution and solvent relaxes slowly toward the diffusive regime no simple zero-time correction can be applied.

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Section: Theoretical Backgroundmentioning

confidence: 98%

Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography

Leo

Paoletti

Ambrosini

2018

Eur. Phys. J. Appl. Phys.

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“…The change of the deflection angle can be described as a local translation of the fringe pattern. For light rays defined as orthogonal trajectories to geometrical wave-front, the equation relating the path of ray to the local index of refraction is [24] grad d d n n ds ds r (11) where r is the position vector of a typical point on a ray and s is the length of ray measured from a fixed point on it.…”

Section: Change Of Refractive Index During Diffusion Process and Corrmentioning

confidence: 99%

“…Laser-based techniques are among the most sensitive methods employed for measuring diffusion coefficient and thermal conductivity [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In this paper we propose an improved version of digital projection moiré to study the refractive index variation in liquid mixtures and hence to measure the diffusion coefficient in mass transfer.…”

Section: Introductionmentioning

confidence: 99%

Measurement of mass diffusion coefficients by digital moiré

2005

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In order to measure small diffusion coefficients of miscible fluids, in this paper we propose an improved version of digital projection moiré. The system uses a simple and flexible fringe generator realized by means of a video projector with a modification of projection optic. The fringe patterns are projected on the bottom of a ground glass plate. The phase object (diffusion cell) is placed in front of the ground glass (in other words, in front of the fringe pattern), which is imaged by a digital video camera. Grating patterns, during the evolution of diffusion phenomena, are captured by a CCD camera and stored in a computer at different times. With the aid of signal demodulating techniques, the images are processed to obtain the diffusion coefficients. The theoretical aspects of the method are presented and the relationship between the fringe shift and the diffusion coefficient is derived. Furthermore, we report some experiments conducted for demonstrating the usefulness of the system.

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“…Knowledge of diffusivity is necessary for the design of chemical equipment and for mass transfer studies. [11][12][13][14][15][16][17][18][19] Additionally, techniques involving interference require optical elements for the splitting and combining of laser beams making them bulky. 1,2 Diffusion in transparent liquid mixtures can be studied using various optical techniques, each having their own advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Imaging of mass transfer process using artificial fringe deflection

2014

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A noninterferometric technique used to measure the diffusion coefficients of transparent liquid solutions is reported. This technique uses a white light source and a diffusion cell, with an artificially developed fringe pattern of dark and white stripes at its entrance. As the diffusion process takes place in the cell, the light passing through this nonuniform refractive index medium will bend toward the higher refractive index region, which results in a fringe shift. This shift in the fringe pattern at different times is recorded in a personal computer (PC) using a CCD camera for the calculation of diffusion coefficients. The fringe shift is calculated after skeletonization and linear fit of the captured fringe system. The diffusion coefficient of different concentrations of ammonium dihydrogen phosphate was determined using the proposed technique and the measured values lay within 1% of the reported values. Detailed theoretical and experimental analyses with a comparison of other existing results are discussed.Chhaniwal, Narayanamurthy, and Anand: Imaging of mass transfer process using artificial fringe deflection Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/18/2015 Terms of Use: http://spiedl.org/terms

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Speckle decorrelation study of liquid diffusion

Cited by 12 publications

References 26 publications

Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography

Effect of noise on measurements of diffusivity in transparent liquid mixtures by digital speckle photography

Measurement of mass diffusion coefficients by digital moiré

Imaging of mass transfer process using artificial fringe deflection

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