Color light sensors are awesome devices for everything from environmental sensors to general robotics. They can be used to monitor slowly changing events like algae blooms or leaf death, or to determine light absorption through a medium. But for all their utility, they have some flaws. First off, they can be complicated to interface to since RGB data often has to be derived using complex signal processing. Secondly, they're less than rugged, and when you want to deploy one in the field you need a device that can stand up to the weather. Even moisture in the air can make an unprotected sensor unreliable.
These problems have been seolved by embedding the light sensor in a rugged housing below a layer of transparent epoxy which protects the sensor from moisture while still allowing light to get in. The resulting light probe is water- and dust-proof, sleet and ice tolerant, non reactive in salt water and will readily sink when submerged. On top of all that, it provides both RGB level (in 8-bit RGB format) and light intensity (in lux) as simple comma separated strings over RS-232!