Far too complicated for me....
http://www.flickr.com/photos/llnl/2829372018/
http://en.wikipedia.org/wiki/National_Ignition_Facility
One of the last steps in the process before reaching the target chamber is to convert the infrared light at 1053 nm into the ultraviolet (UV) at 351 nm in a device known as a
frequency converter.These are made of thin sheets cut from a single crystal of
potassium dihydrogen phosphate. When the 1053 nm (IR) light passes through the first of two of these sheets, frequency addition converts a large fraction of the light into 527 nm light (green). On passing through the second sheet, frequency combination converts much of the 527 nm light and the remaining 1053 nm light into 351 nm (UV) light. IR light is much less effective than UV at heating the targets, because IR couples more strongly with hot
electrons which will absorb a considerable amount of energy and interfere with compressing the target. The conversion process is about 50% efficient, reducing delivered energy to a nominal 1.8 MJ.