A comparison of SAW and optical dew point measurement techniques

A comparison of SAW and optical dew point measurement techniques in the areas of condensation sensitivity, surface contamination effects, frost point transition behavior, and dew point measurement resolution was made using a novel hybrid SAW/optical sensor. In addition SAW frequency was used to compare SAW dew point measurements to a commercial optical sensor. The SAW dew point sensor was found to be much less susceptible than the optical technique to surface contamination. The frost point transition was found to cause significant instability to the dew point measurements when controlling condensation density with SAW velocity, or optical reflection voltage. SAW amplitude provided continuous dew point measurements. A SAW oscillator dew point system had a measurement resolution of 0.03/spl deg/C as compared to a resolution of 0.2/spl deg/C for a commercial optical dew point hygrometer.