Non linear magic

This bright green glowing set of optics you can see here is part of a piece of kit known as an OPO (optical parametric oscillator). I use it to take images of biological specimens such as this.

The crystal inside the OPO converts light of one colour (which in this case is green with a wavelength of 532 nm) into two different colours. The total energy of the light out has to equal the total energy of the light going into the crystal (due to conservation of energy - in this lab, we don't violate the laws of thermodynamics, no matter how hard we might try). The different colours you get out depend on the temperature of the crystal, and this can be precisely controlled to enable me to probe particular chemical bonds in my sample.

It's all very nifty, expensive, fun stuff. I'll be working in the lab until about 10 p.m. tonight. Bring on the nth cup of tea!