In the words of Gamechanger Audio:

The LIGHT Pedal is the worlds first analog optical spring reverb system
that uses infra-red optical sensors. This system is used to harvest the
full timbral and harmonic range of the spring reverb tank. The LIGHT
Pedal combines the best features of a classic spring reverb with the
innovative optical sensor system and a powerful effects section. This
combination opens up countless new types of reverb textures and sounds
never heard before.