History of Photosound
What is Photosound?
Photosound is a collective term to include photoacoustic, optoacoustic and thermoacoustic imaging and detection methods. It was first mentioned in Alexander Graham Bells Paper called Production of Sound by Light in 1880. Bell was experimenting with long-distance sound transmission. Through his invention, called “photophone”, he transmitted vocal signals by reflecting sun-light from a moving mirror to a carbon disulfide photo resistor. As a byproduct of this investigation, he observed that sound waves were produced directly from a solid sample when exposed to beam of sunlight that was rapidly interrupted with a rotating slotted wheel. He noticed that the resulting acoustic signal was dependent on the type of the material and correctly reasoned that the effect was caused by the absorbed light energy, which subsequently heats the sample. Later Bell showed that materials exposed to the non-visible (ultra-violet and infra-red) portions of the solar spectrum can also produce sounds and invented a device, which he called “spectrophone”, to apply this effect for spectral identification of materials. Bell himself and later John Tyndall and Wilhelm Röntgen extended these experiments, demonstrating the same effect in liquids and gases.[3,4] However, the results were too crude, dependent on ear detection, and this technique was soon abandoned. The application of the photoacoustic effect had to wait until the development of sensitive sensors and intense light sources.
In 1938 Mark Leonidovitch Veingerov revived the interest in the photoacoustic effect, being able to use it in order to measure very small carbon dioxide concentration in nitrogen gas (as low as 0.2% in volume).  The invention of lasers further invigorated the field.  It provided the field with a high power monochromatic, pulsed source of excitation.  This lead to biomedical applications for sensing and imaging of turbid media. [8,9] as seen today.
5. Veingerov, M.L. (1938). “New Method of Gas Analysis Based on Tyndall-Roentgen Opto-Acoustic Effect”. Dokl. Akad. Nauk. USSR 19: 687.
6. Gould, R. Gordon (1959). “The LASER, Light Amplification by Stimulated Emission of Radiation”. In Franken, P.A. and Sands, R.H. (Eds.). The Ann Arbor Conference on Optical Pumping, the University of Michigan, 15 June through 18 June 1959. p. 128. OCLC 02460155.
7. Gusev, V.E. Karabutov A. A. (1993) Laser Optoacoustics AIP Press ISBN 1-5639-036-2
8. Bowen T. (1981) Radiation-induced thermoacoustic soft tissue imaging. Proc. IEEE Ultrasonics Symposium 1981;2:817-822.
9. Oraevsky AA, Jacques SL, Esenaliev RO, Tittel FK. Laser-based optoacoustic imaging in biological tissues. Proc. SPIE 1994;2134A:122-128.