AQMS-700 CAPS NO2 analyzer is an atmospheric environment monitoring instrument based on the optical cavity attenuation phase shift technology (CAPS) which can directly measure the NO2 concentration in the ambient air and is widely used in the online monitoring of the NO2 content in the ambient air quality monitoring scene.
The analyzer is mainly composed of pre-processing module, resonant cavity module, flow control module, circuit module, etc., and will measure the gas concentration according to the phase difference between the beam in the reference cavity and the cavity with NO2. The LED beam is modulated by high frequency signal and coupled into the optical cavity composed of high-reflection mirror. Then, beam is reflected repeatedly in the cavity and is absorbed by NO2 in the cavity. The absorbed beam is collected by the detector after passing through the optical cavity and the optical filter. The detector converts the optical signal into electrical signal, then demodulates it by electrical heterodyne method, and finally obtains the signal with phase information.