Humidity Interlock for Protecting a Cooled Laser Crystal

A humidity interlock has been developed to prevent damage that could be caused by condensation of water on a delicate and expensive laser crystal that must be maintained at a temperature below ambient during operation. The humidity interlock is installed in conjunction with the laser temperature controller system. Whenever the humidity inside the laser housing rises beyond a safe level, the humidity interlock turns off power to a thermoelectric cooler on which the laser crystal is mounted.