Monitoring of environmental nitrogen dioxide concentration using visible acousto-optic differential optical absorption spectroscopy

A. Y.S. Cheng*, Mau Hing CHAN

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

3 Citations (Scopus)


Atmospheric concentration measurement of nitrogen dioxide (NO2) pollutant was demonstrated by a new type of differential optical absorption spectroscopy (DOAS) using a spectral scanning device of a visible acousto-optic tunable filter. The measurement requires a stable artificial light source such as a xenon lamp, and the light beam is directed into the environment where the concentration of NO2 is to be monitored. The retrieval of NO 2 concentration is then achieved by analyzing the residual light using the DOAS signal processing. In this paper, we present results obtained from this new DOAS system during continuous measurement of atmospheric NO 2 concentration in the campus of the City University of Hong Kong. Another DOAS system, using a miniature CCD grating spectrometer, was established as a control experiment. The CCD spectrometer acts as a traditional DOAS system for performance evaluation. Instead of using the NO2 absorption cross section for concentration retrieval, differential absorption area provides an alternative quantity for concentration retrieval. The monitoring results from both of the DOAS systems are compared with the pollutant concentrations reported in a nearby pollutant monitoring station, operated by the Hong Kong Environmental Protection Department.

Original languageEnglish
Article number39
Pages (from-to)301-311
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2004
EventRemote Sensing of Clouds and Atmosphere IX - Maspalomas, Spain
Duration: 13 Sept 200415 Sept 2004

Scopus Subject Areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

User-Defined Keywords

  • Acousto-optic tunable
  • Atmospheric pollutant monitoring
  • Differential absorption spectroscopy
  • Visible spectroscopy


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