This project was motivated by a desire to analyze and discuss the shortcomings of our dependence on corporate communication networks.
As we keep delegating more and more of our daily lives to fewer and fewer digital platforms, using wires and towers owned by a handful of telecommunication companies, and watched over by an even smaller number of agencies, it becomes important to consider practical and conceptual alternatives for our affections.
On one hand, a laser modem provides a very direct, secure and personal communication channel that can be built to connect points at distances much greater than WiFi could cover.
On the other hand, the point-to-point nature of the link and the fact that it relies on a very thin beam of light to transmit data make it very susceptible to misalignment, interruptions and interference.
A most tenuous connection indeed!
As this is mostly a proof of concept and art installation, we focused on getting one-way communication working, but the circuits could easily be replicated to build two-way transceivers.
A couple of other groups and individuals thinking about similar issues:
Ronja: This design from a group in the Czech Republic uses car brake lights to transmit data at 10Mbps.
Laser gun game: This is the most interesting for this kind of prototype, but we couldn’t get the tone decoder PLL ICs in time, and designing the filters can make for an interesting second version. We decided to focus on a simpler version of this.
Laser Transceiver Instructables: This is a good starting point, but we couldn’t get it to work at distances greater than 1 meter, much less 345 meters. There’s no way a 5mW laser and a single photodiode produce enough current, with low enough noise, for the ATmega168 to pick up. I also don’t think a 5mW laser with crappy optics can go 345 meters.