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.

Benefits 
• Adopt ultra-high reflector, low detection limit;
• Direct measurement, without reagent or catalytic conversion, low maintenance;
• Strong anti-interference ability;
• Simple structure and parts; 
• Strong system stability, low power consumption;
• Fast response;

Application 
• Atmospheric background station, urban environment and other conventional monitoring;
• Laboratory ultra-high requirement monitoring;
• NO₂ concentration monitoring in special areas such as hospitals;