A new multipurpose UV-Vis spectrometer for air quality monitoring and climatic studies

Abstract

The multipurpose ultraviolet-visible (UV-Vis) remote sensing equipment SPATRAM (SPectrometer for Atmospheric TRAcers Monitoring) is a scanning spectrometer for measurement of electromagnetic radiation in the 250–950 nm spectral range. In this paper SPATRAM will be presented and new solutions will be discussed. The monochromator is based on the one installed in GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences) developed during the 1990s. The most important improvements of SPATRAM relative to GASCOD are: (i) the wider spectral range scanned, allowing for the detection of more atmospheric compounds than with GASCOD; (ii) an increased number of inputs, resulting in the possibility of quasi-simultaneous measurements from different optical devices; (iii) the focusing optic system, which permits a simple optical alignment procedure and low cost; (iv) electronic self-thermoregulation, allowing for reliable spectral measurements unaffected by mechanical deformation caused by variation of temperature; (v) adoption of a CCD sensor, resulting in an increase of equipment sensitivity and therefore an enhancement in time resolution of the measurements; (vi) the use of an advanced CPU and a standard OS, guaranteeing full stability of the equipment; and (vii) the development of a new software tool for complete control of the whole instrument and for pre-processing of the measured data.

Acknowledgements

The work was funded by the Portuguese FCT through projects PDCTE/CTA/49828/2003 and POCI/AMB/ 59774/2004. The author DB was financially supported by FCT through grant SFRH/BPD/22160/2005.

The authors would like to thank Manuele Turini and all the staff of the DTA (http://www.dta.it) for their support and suggestions in the development of the electronic parts of the equipment, as well as Adriano Gabellini of the COM, Mechanical Opto Components, for continuous additional work requested on the mechanical apparatus. Many thanks also to the Energy Transfer and Minor Gases in the Atmosphere group of the ISAC Institute, namely Fabrizio Ravegnani, Ivan Kostadinov and Andrea Petritoli.