Ultrafast time-gated ballistic-photon imaging and shadowgraphy in optically dense rocket sprays Export

@article{citeulike:4083036, abstract = {Time-gated ballistic-photon imaging is a form of shadowgraphy in which an ultrashort, optical-Kerr-effect (order 2 ps) time gate is used to enhance the relative intensity of ballistic versus multiply scattered photons. In the current work, this technique is adapted for what is believed to be the first time for use in the moderately dense environment (optical density \~{}1.5 to 2) of a high-speed 5 to 15 mm diameter rocket spray to improve image contrast and observe liquid-breakup phenomena. Unlike coherence gating, which is another form of ballistic imaging, the time-gating approach allows sufficient signal levels from ballistic and near-ballistic photons to enable time-resolved single-shot imaging. Direct comparisons with non-time-gated shadowgraphy indicate that the two techniques are sensitive to different features of the flowfield, with regions composed of a dense field of droplets being highly attenuated in conventional shadowgrams but appearing transparent to ballistic photons. This enables significant image contrast enhancement (\~{}6.6∶1) of liquid-core structures and facilitates improved understanding of the primary and secondary breakup processes in sprays of moderate optical density.}, author = {Schmidt, Jacob B. and Schaefer, Zane D. and Meyer, Terrence R. and Roy, Sukesh and Danczyk, Stephen A. and Gord, James R.}, citeulike-article-id = {4083036}, citeulike-linkout-0 = {http://dx.doi.org/10.1364/AO.48.00B137}, citeulike-linkout-1 = {http://www.opticsinfobase.org/abstract.cfm?id=175612}, day = {1}, doi = {10.1364/AO.48.00B137}, journal = {Appl. Opt.}, keywords = {combustion, diagnostics}, month = {February}, number = {4}, pages = {B137--B144}, posted-at = {2009-02-23 06:08:08}, priority = {2}, publisher = {OSA}, title = {Ultrafast time-gated ballistic-photon imaging and shadowgraphy in optically dense rocket sprays}, url = {http://dx.doi.org/10.1364/AO.48.00B137}, volume = {48}, year = {2009} }

TY - JOUR ID - citeulike:4083036 L3 - citeulike-article-id:4083036 N2 - Time-gated ballistic-photon imaging is a form of shadowgraphy in which an ultrashort, optical-Kerr-effect (order 2 ps) time gate is used to enhance the relative intensity of ballistic versus multiply scattered photons. In the current work, this technique is adapted for what is believed to be the first time for use in the moderately dense environment (optical density ~1.5 to 2) of a high-speed 5 to 15 mm diameter rocket spray to improve image contrast and observe liquid-breakup phenomena. Unlike coherence gating, which is another form of ballistic imaging, the time-gating approach allows sufficient signal levels from ballistic and near-ballistic photons to enable time-resolved single-shot imaging. Direct comparisons with non-time-gated shadowgraphy indicate that the two techniques are sensitive to different features of the flowfield, with regions composed of a dense field of droplets being highly attenuated in conventional shadowgrams but appearing transparent to ballistic photons. This enables significant image contrast enhancement (~6.6∶1) of liquid-core structures and facilitates improved understanding of the primary and secondary breakup processes in sprays of moderate optical density. IS - 4 JF - Appl. Opt. EP - B144 TI - Ultrafast time-gated ballistic-photon imaging and shadowgraphy in optically dense rocket sprays PB - OSA VL - 48 SP - B137 KW - combustion KW - diagnostics AU - Schmidt, Jacob AU - Schaefer, Zane AU - Meyer, Terrence AU - Roy, Sukesh AU - Danczyk, Stephen AU - Gord, James PY - 2009/02/01/ UR - http://dx.doi.org/10.1364/AO.48.00B137 ER -