SO2 and NO2, gases selectively and characteristically absorb light from scattered solar radiation (skylight) as it passes through the atmosphere. By correlating the resulting absorption spectrum with corresponding reference spectra etched onto a disc inside the unit, the COSPEC measures, in real time, the integrated concentration of SO2 or NO2 along the line of sight, independently of the presence of other potentially interfering gases.

The COSPEC, incorporating a unique proprietary mask design, has a high signal to noise ratio and is sufficiently sensitive to track plumes over great distances under adverse weather conditions. Internal signal processing compensates for changing ambient light levels and diurnal spectral shifts.

Over 180 COSPECs are currently in use worldwide.

  • Specifications

Target Gases

SO2 or NO2

Field of View

10 x 30 mrads

Limit of Detection

2.5 ppm-m

Dynamic Range

0-1000 ppm-m standard (other ranges available)

Operating Temperature

0 -50 degrees celsius


78 x 38 x 22 cm




LabView based software

Light Sources, Spectrometers, Monochromators, Detectors , Components and Systems from Extreme Ultraviolet (EUV) to Infrared (IR)

Resonance Ltd  | Telephone (705)733-3633