Frequency conversion of CO2 laser radiation to the 0.5 μ range in nonlinear crystals

A study was made of frequency conversion of CO₂ laser radiation to the 0.5 μ range in two stages: first, the radiation was converted to the near infrared in crystals capable of handling middle infrared range and then to the visible range in a crystal of lithium iodate. In both stages the pump radiation was provided by a YAG laser. The conversion efficiencies were 8–14%, depending on a crystal. This made it possible to record reliably the middle infrared radiation with a sensitivity equivalent to that of a photomultiplier characterized by a quantum efficiency of 1–2%.