Acoustic steering of audible and ultrasonic waves using THermally-induced Optical Reflection of Sound (THORS)

Daniel S. Kazal; Ellen L. Holthoff; Brian M. Cullum

doi:10.1117/12.2588224

12 April 2021 Acoustic steering of audible and ultrasonic waves using THermally-induced Optical Reflection of Sound (THORS)

Daniel S. Kazal, Ellen L. Holthoff, Brian M. Cullum

Author Affiliations +

Proceedings Volume 11757, Smart Biomedical and Physiological Sensor Technology XVIII; 117570F (2021) https://doi.org/10.1117/12.2588224
Event: SPIE Defense + Commercial Sensing, 2021, Online Only

Abstract

In this work, we describe the phenomenon, Thermally-induced Optical Reflection of Sound (THORS), and how it can be used to optically steer acoustic waves around a 90 degree corner of a physical obstruction, where observed acoustic amplitudes are increased by a factor of 30. In addition, we discuss the introduction of ultrasonic waves to the THORS phenomenon, and preliminary results for THORS barriers generated in ambient air, using a 5.3-5.7 μm CO laser source.The manipulation and guiding of sound waves have typically required the use of physical barriers for the reflection of an incident pressure wave. With the manipulation of acoustic waves being critical for many applications in scientific and engineering fields, including subsurface tissue imaging, photoacoustic sensing, secure communications, acoustic stealth technology, and acoustic design engineering; the requirement for physical barriers often represents a significant limitation. The recently discovered phenomenon THermally-induced Optical Reflection of Sound (THORS), provides the ability to generate acoustically reflective barriers, in air, by exciting media in the path of an IR laser beam, causing abrupt changes in compressibility between the excited and surrounding media. In this work, we demonstrate the ability to efficiently reflect sound waves around physical obstructions using a laser. Additionally, this work demonstrates the ability to also manipulate ultrasonic waves via THORS barriers, where the reflection and suppression of ultrasonic pulses in the frequency range of 120-300 kHz are shown. Finally, preliminary results demonstrating the ability to employ THORS in ambient air using water vapor as the absorbing media and a 5.5 μm CO laser beam for excitation.

Conference Presentation

Citation Download Citation

Daniel S. Kazal, Ellen L. Holthoff, and Brian M. Cullum "Acoustic steering of audible and ultrasonic waves using THermally-induced Optical Reflection of Sound (THORS)", Proc. SPIE 11757, Smart Biomedical and Physiological Sensor Technology XVIII, 117570F (12 April 2021); https://doi.org/10.1117/12.2588224

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