Lasers are red, lasers are blue

Calcium is a happy element that likes to mix with others - as we mostly see in bones, limescale and rocks. These compounds usually appear white, like the Cliffs of Dover or bones, but calcium atoms themselves would shiny red or blue if isolated. So to interact with calcium we need to used red and blue lasers.

This experiment takes calcium atoms cools them down to a thousand of a degree above absolute zero - or -273.149?. The blue light is made by using a powerful green laser to pump an infrared laser which is then converted into blue light using a technique known as frequency doubling. The red light comes from a relatively simple laser diode.