Optical Interferometry of Inhomogeneous Gases

Howes, Walton L.; Buchele, D. R.

doi:10.1364/josa.56.001517

Cited by 35 publications

(11 citation statements)

References 7 publications

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“…A residual shadowgraph image remains whose effect varies with the ratio of the length of the source ͑the flame in our case͒ to the focal length of the imaging lens. Howes and Buchelle 19 show that if the refractive-index gradient is a linear function of distance, the image is distortionless provided that the center of the test section ͑the flame in our case͒ is imaged at the detector surface. A 2-D soot optical system incorporating virtually distortionless imaging is described below.…”

mentioning

confidence: 93%

Two-dimensional imaging of soot volume fraction in laminar diffusion flames

et al. 1999

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/npsi/ctrl?action=rtdoc&an=3535830&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=3535830&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1364/AO.38.002478Applied Optics, 38, 12, pp. 2478Optics, 38, 12, pp. -2485Optics, 38, 12, pp. , 1999 Two-dimensional imaging of soot volume fraction in laminar diffusion flames Snelling, David R.; Thomson, Kevin A.; Smallwood, Gregory J.; Gülder, Ömer L. Two-dimensional imaging of soot volume fraction in laminar diffusion flamesDavid R. Snelling, Kevin A. Thomson, Gregory J. Smallwood, and Ö mer L. Gü lder A technique for acquiring two-dimensional soot-volume-fraction measurements in laminar flames has been demonstrated. The technique provides a map of very low noise concentration over a range of wavelengths ͑250 -1100 nm͒. A noise level of 0.0007 in extinction and a spatial resolution of 30 -40 m for soot concentration were achieved with an arc lamp source that was filtered to provide greater spatial coherence and a CCD detector. The broadband arc lamp source also allowed us to avoid the added noise resulting from speckle with coherent laser sources. Beam steering, due to refractive-index gradients in the flame, was measured and compared with theoretical predictions. The optical arrangement to minimize the effect of beam steering is described. As a result the beam steering had no effect on the soot measurements in the flames examined. Flame-transmission maps obtained with this system in an ethylene͞air laminar diffusion flame are presented. Tomographic analysis from use of an Abel inversion of the line-of-sight data to obtain radial profiles of soot concentration is described.

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confidence: 93%

Two-dimensional imaging of soot volume fraction in laminar diffusion flames

et al. 1999

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“…The gradients were then integrated in a vertical fashion from the boundary defined by the bottom surface of the pool. For this particular combination of optical path length and optical properties of the test liquid, the measurement sensitivity is of the order of 1 mdeg C. This figure neglects any image-plane distortions that are produced, particularly in those regions where terms of second order or higher are nonnegligible, 11 as is the case in the immediate vicinity of the radiantly heated liquid surface. Regardless, the resulting sensitivity is substantial, particularly in light of the fact that the decollimating optics in this case has a modest focal length of only 304 mm.…”

Section: Applications and Discussionmentioning

confidence: 97%

“…This eliminates numerous complications such as intensity fluctuations of the source, pixel-to-pixel variations in gain within a given detector array or from one detector to another, absorption or scattering of light within the test section, or section-order intensity variations resulting from asymmetric refractiveindex distributions. 11 An example of a color basis that does not possess these properties is the RGB (red, green, and blue) representation provided by most conventional color video systems. The tristimulus values must be combined according to some predetermined formalism to yield the net perceived color, and each of the three values of R, G, and B are themselves dependent on the absolute intensity.…”

Section: Color-based Filteringmentioning

confidence: 99%

Quantitative rainbow schlieren deflectometry

Greenberg

Klimek

Buchele³

1995

Appl. Opt.

Self Cite

104

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In the rainbow schlieren apparatus, a continuously graded rainbow filter is placed in the back focal plane of the decollimating lens. Refractive-index gradients in the test section thus appear as gradations in hue rather than irradiance. A simple system is described wherein a conventional color CCD array and video digitizer are used to quantify accurately the color attributes of the resulting image, and hence the associated ray deflections. The present system providesva sensitivity comparable with that of conventional interferometry, while being simpler to implement and less sensitive to mechanical misalignment.

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“…For every rotation angle ö, the object projection images P ö (integrated phase and integrated amplitude) [ Fig. 1(a)] are captured by means of interferometry [5] (including holography [6]). In order to properly reconstruct an object internal structure, the captured projection images must well approximate object integrated phase and amplitude distributions.…”

Section: Introductionmentioning

confidence: 99%

Investigation of limitations of optical diffraction tomography

Kozacki

Kujawińska

Kniazewski

2007

Opto-Electronics Review

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Optical diffraction tomography (ODT) applied to measurement of optical microelements is limited by low dynamic range, i.e., only objects with small deviations of refractive-index distribution can be measured. Therefore in this paper the limitations and errors of ODT are investigated throughout extensive numerical experiments. It is shown that these errors can be reduced by introduction of additional numerical focusing in the tomographic reconstruction algorithm. Additionally, new tomographic reconstruction algorithm using back propagation in reference medium for optical microelements measurement with known design is proposed. This hybrid reconstruction algorithm allows significant extension of ODT applicability in measurement of elements having large deviations of refractive-index distribution.

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Optical Interferometry of Inhomogeneous Gases

Cited by 35 publications

References 7 publications

Two-dimensional imaging of soot volume fraction in laminar diffusion flames

Two-dimensional imaging of soot volume fraction in laminar diffusion flames

Quantitative rainbow schlieren deflectometry

Investigation of limitations of optical diffraction tomography

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