The manipulation and control of sound waves plays a key role in many scientific and engineering fields, such as acoustic engineering, secure communications, photoacoustic sensing, etc. Using infrared absorption, we can heat molecules in the air with a laser to create a barrier for abrupt changes in compressibility.
This difference in compressibility causes sound to reflect off that barrier, similar to how sound waves reflect off a wall when traveling through air. In order to manipulate these sound waves without the use of rigid, physical structures, we use the recently investigated phenomenon, thermally-induced optical reflection of sound (THORS). In this work, we evaluate the use of THORS and it’s potential to generate reflective barriers in tissue phantoms (bovine gelatin) using ultrasound. This provides potential biological applications of photoacoustic imaging in the body, such as brain tumors.