Speaking Through Light

A prototype for free space optical communications using light as a citizen band. Short: A low-cost light walkie talkie.

The electromagnetic field is a widely used medium for the transportation of information. Its use in communicating through free space (that is air, meaning not using fiber-optic or electric cables) is mostly limited to the invisible radio spectrum. The visible approach, using light for long-range communication, comes with practical downsides: Sender and receiver always need to be in line of sight and atmospheric absorption limits the usable range. Optical wireless communication technologies are most widespread through infrared remote controls, yet their use can be found far beyond entertainment systems. Internet satellites communicate via precisely aligned lasers using the advantage of light communication: high data throughput. While being impractical on earth, free space visible light communication enables us to perceive electromagnetic data-streams directly through our own eyes, without the need for external transducers, bringing it closer to our perception, facilitating an intuitive understanding of the technology.

This project, developed at PIFcamp, explores how light can be used to transport sound through space. The vast landscape of Triglavski narodni park offered the perfect dimensions for long-range light transmissions. We explored how sound-carrying light beams look, how living nature alters the light, and how this affects the tonal properties of the transmitted sound. We looked at light as a specific form of electromagnetic radiation and used radio technology to modulate and demodulate the streams of photons.

The first long-range test of the system.

The oscillations of a dimmed flashlight serve as a easy to generate test signal.

A system diagram of the prototype.

The first successfull music transmission, sending Prada by Arca through light.