Thermally Induced Optical Reflection of Sound (THORS) in Ambient Air: Characterization and Temporal Dynamics
| dc.contributor.author | Kazal, Daniel S. | |
| dc.contributor.author | Reardon, Alex J. | |
| dc.contributor.author | Cullum, Brian | |
| dc.date.accessioned | 2022-07-12T16:42:04Z | |
| dc.date.available | 2022-07-12T16:42:04Z | |
| dc.date.issued | 2022-07-05 | |
| dc.description.abstract | Thermally induced optical reflection of sound (THORS) provides a means to manipulate sound waves without the need for traditional acoustically engineered structures. By photothermally exciting a medium, with infrared light, a barrier can be formed due to abrupt changes in compressibility of the excited medium. Discovery and initial characterization of the THORS phenomenon utilized air saturated with ethanol vapor as the absorbing medium and a CO2 laser, operating at 9.6 µm, as the excitation source to achieve acoustic reflection efficiencies of 25–30% of the incident wave. In this work, we demonstrate for the first time, the ability to generate THORS barriers in ambient air (i.e., without the need for ethanol vapor). Employing atmospheric water vapor as the absorbing medium and a modulated, multiline carbon monoxide laser, operating at 5.5 ± 0.25 µm, THORS barriers capable of acoustic and ultrasonic reflection–suppression efficiencies greater than 70% are readily generated. To achieve these significant reflection–suppression efficiencies, the temporal dynamics of THORS barriers in ambient air were characterized using 300 kHz ultrasonic pulses incident on the barriers, revealing three different operational regimes. In the first regime, a single laser pulse generates a transient THORS barrier that lasts tens of milliseconds and exhibits minimal acoustic reflectivity. In the second regime, multiple laser pulses interact with the water vapor prior to complete relaxation of the THORS barrier from the previous excitation pulse, resulting in an additive response and reflectivity/suppression efficiencies as great as 72%. Finally, in the third regime, non-modulated continuous wave (CW) excitation of the water vapor occurs resulting in no measurable acoustic reflectivity/suppression from the THORS barrier. This work characterizes these different regimes and the optimal modulation timing to generate efficient continuous acoustic barriers using THORS. | en_US |
| dc.description.sponsorship | The authors would thank Drs. Darren Emge and Eric Languirand of the U.S. Army Combat Capabilities Development Command, Chemical Biological Center, for loan of the ACO Pacific microphone. The authors would also like to gratefully acknowledge the U.S. Army Research Office and the University of Maryland, Baltimore County for funding this work, as well as the U.S DoD SMART Fellowship Program for the support of Ph.D. candidate Daniel Kazal. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors would like to gratefully acknowledge the U.S. Army Research Office (W911NF-11-D-0001) and the University of Maryland Baltimore County for funding this work as well as the U.S. DoD SMART Fellowship program (SMART ID: 2020-13898) for the support of PhD candidate DSK. | en_US |
| dc.description.uri | https://journals.sagepub.com/doi/abs/10.1177/00037028221109238 | en_US |
| dc.format.extent | 10 pages | en_US |
| dc.genre | journal articles | en_US |
| dc.genre | postprints | en_US |
| dc.identifier | doi:10.13016/m2hprg-edpu | |
| dc.identifier.citation | Kazal, Daniel S., Alex J. Reardon, and Brian Cullum. “Thermally Induced Optical Reflection of Sound (THORS) in Ambient Air: Characterization and Temporal Dynamics.” Applied Spectroscopy, (June 2022). https://doi.org/10.1177/00037028221109238. | en_US |
| dc.identifier.uri | https://doi.org/10.1177%2F00037028221109238 | |
| dc.identifier.uri | http://hdl.handle.net/11603/25134 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Sage | en_US |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Chemistry & Biochemistry Department Collection | |
| dc.relation.ispartof | UMBC Faculty Collection | |
| dc.relation.ispartof | UMBC Student Collection | |
| dc.rights | This work has been accepted for publication in Applied Spectroscopy. | en_US |
| dc.title | Thermally Induced Optical Reflection of Sound (THORS) in Ambient Air: Characterization and Temporal Dynamics | en_US |
| dc.title.alternative | Thermally-induced Optical Reflection of Sound in Ambient Air: Temporal Characterization of THORS Barriers | |
| dc.type | Text | en_US |
| dcterms.creator | https://orcid.org/0000-0002-5250-8290 | en_US |