The portable cold mirror dew point meter is a precision instrument used to measure the dew point temperature of gases, achieving high-precision humidity detection through the condensation phenomenon on the surface of the optical cold mirror. Using the principle of cold mirror, the temperature of the cold mirror is accurately controlled to condense water vapor in the gas into dew drops. The temperature at which dew drops form is measured as the dew point temperature.
The precision optical cold mirror is cooled by a refrigeration system. When the measured gas flows through the surface of the cold mirror and the temperature drops to the dew point, water vapor condenses into dew drops. A high-precision optical detection system, such as a photoelectric sensor, monitors changes in the reflection of light on the surface of a cold mirror. When the intensity of the reflected light changes significantly, it indicates the formation of dew drops. At this time, the mirror surface temperature measured by the temperature sensor is the dew point temperature of the gas.
The core working principle of the portable cold mirror dew point meter is based on the cold mirror method, and the specific steps are as follows:
Mirror cooling: The built-in refrigeration system actively reduces the temperature of the mirror, gradually bringing the water vapor in the gas closer to saturation.
Condensation layer formation: When the mirror surface temperature drops to the gas dew point, water vapor condenses into liquid dew or solid frost on the mirror surface, forming a visible condensation layer.
Optical detection: Real time monitoring of specular reflection intensity using an optical system composed of LED light source and photodiode. After the formation of the condensation layer, the specular reflection light undergoes diffuse reflection, and the light intensity received by the photoelectric sensor decreases.
Temperature measurement and balance: High precision platinum resistance thermometer embedded in the mirror surface, directly measuring the mirror surface temperature at condensation equilibrium. The control system adjusts the cooling power to dynamically balance the mirror temperature at the dew point state (where the evaporation rate is equal to the condensation rate), which is the dew point temperature of the gas.
Parameter conversion: Dew point temperature can be calibrated and converted into parameters such as relative humidity and humidity to meet the needs of different scenarios.
Mirror maintenance
Cleaning method: Use a dust-free cloth dipped in anhydrous ethanol to gently wipe the mirror surface and light path window to avoid scratching the surface. If the mirror contamination is severe, it can be repeatedly heated and cooled several times to remove residue.
Heating treatment: If the exposed layer is too thick or frozen, the heating function can be briefly turned on to accelerate the evaporation of water, and the measurement can be restarted after the exposed layer indicator light returns to a dry state.