Fountain with internal illumination
The Laser Fountain is a recirculating fountain consisting of three water jets into a basin. The water jets are arranged with coaxial laser illumination. Because of total internal reflection, the laser light follows the arc of each water stream.
In practice, the nozzles consist of a pipe T-junction with a glass
window epoxied across from the nozzle on the crossbar, and the water
input down the leg. The laser shines right through the window and out
the nozzle, coaxial with the jet.
The long collimating nozzle helps generate a smooth unbroken jet of water. If if you cup your hands under the stream, you are rewarded with a pretty handful of wet green light.