Experiments of Cryogenic Dew and Frost Point Hygrometer for Upper Air Sounding

摘要

An experiment device of cryogenic dew and frost point hygrometer is designed based on physical mechanism. Dew and frost on the chilled mirror are detected by transmitting an IR light with wavelength of 850 nm to mirror and receiving the reflected light after absorption of dew or frost by a photodiode. Special novel signal processing technologies for photoelectric integral and ambient light power suppression make the measurements can be done without any light shield. Peltier thermoelectric cooler (TEC) module is employed to heating or chilling mirror for clear or dew or frost, and served by Fuzzy-PID control logic algorithms and high-efficiency, switch-mode driver. Experiment results show that the instrument measuring dew or frost temperature is very accuracy and error less than 0.2 Celsius degree.