heliophone

A heliophone is a device that produces sound by using a beam of light. The most common type of heliophone, invented by William Henry Leblanc in 1878, works by interrupting a beam of light with a vibrating diaphragm. This interruption causes fluctuations in the intensity of the light beam, which are then converted into sound by a photoelectric cell.

The heliophone was an early form of optical sound reproduction and served as a precursor to modern optical sound tracks on film. While not widely adopted for commercial use due to its limitations and the advent of more practical sound recording technologies, it demonstrated the principle of converting light variations into audible sound. Other inventors, such as Alexander Graham Bell, also experimented with heliophone-like devices, exploring different methods of light-based sound transmission. The fundamental concept involved modulating a light beam and then detecting those modulations to reconstruct the original sound wave. This principle has found applications in various fields, though the term "heliophone" typically refers to these historical optical sound devices.