Section News

Son et Lumiere | Music Transmission with Light and Mirrors – a DIY Guide

The newly formed IEEE photonics society branch at City, University of London has been very busy over the past few months in coming up with and running a wonderful series of photonics “Hackathons”, which involve interesting, interactive and very easy to do experiments to demonstrate the wonders of photonics and inspire school pupils and undergraduates alike.

One of these experiments demonstrates how a beam of light can be used to carry information. Specifically Amplitude Modulation (AM) of light is used to transmit sound (information) on a carrier (light) beam.

This is shown in the short video and the only way to disrupt the sound is by blocking the path of the light (e.g. with your hand), or by reflecting the light away from the receiver using mirrors.

The setup involves having a light modulator, which is provided by plugging a special flashlight transmitter into a mobile phone, play a song, and the sound “rides” along the light beam to the photovoltaic receiver. The mirrors will allow you to direct the light beam on any path you like.

If you want to recreate this in your school, you will need the following:
This is the light modulator, the main reason we could carry out the experiment. In this kit, you have a light that has an audio jack which you can plug into your phone to play any sound or music that you desire. There’s also the photovoltaic receiver that will play the sounds when the light hits the solar panels.
This link is the mirrors that we used that can bounce and reflect the light.
This link is to the wooden blocks that we used to hold up the mirrors, and we could use them to also block the light.
This link refers to the black cloth that we used so that other light sources don’t interfere and get detected by the receiver.

In addition, batteries are required for the light modulator and clear tape to stick the mirrors to the blocks.