Photoacoustic imaging: The sound of light
- IF LIGHT passed through objects, rather than bouncing off them, people might now talk to each other on â€śphotophonesâ€ť. Alexander Graham Bell demonstrated such a device in 1880, transmitting a conversation on a beam of light. Bellâ€™s invention stemmed from his discovery that exposing certain materials to focused, flickering beams of light caused them to emit soundâ€”a phenomenon now known as the photoacoustic effect.It was the worldâ€™s first wireless audio transmission, and Bell regarded the photophone as his most important invention. Sadly its use was impractical before the development of optical fibres, so Bell concentrated instead on his more successful idea, the telephone. But more than a century later the photoacoustic effect is making a comeback, this time transforming the field of biomedical imaging.