Vaisala CT12K Celiometer
This device uses dual optics and a Class 1 Laser to identify cloud conditions using backscatter principle. The Laser used is invisible to the naked eye.
The CT12K uses a dual lens arrangement to determine cloud base height; one optical path for the transmitter and a separate optical path for the receiver. The operating wavelength of the Gallium Arsenide pulsed laser diode transmitter is 904 nm. The CT12K is equipped with a heater and blower housing to prevent snow and ice accumulation on the windows of the instrument cover. The model CT12K has an advertised maximum reportable cloud base detection range of 4000 meters (12,000 ft) above the surface. Initial tests have shown some interesting results, where cloud can be seen changing before a weather event occurs such as showers etc.
Unfortunatly, we have found an issue with the power supply on the CT12K and are awaiting news on a replacement / repair. The receiving script has now been re-written to use a Ubuntu Linux Server as it's host, taking the raw serial output and processing it, sending results to a mysql database. The CT12K will be back on-line when the power supply issue is fixed.