• T640-PM web
  • GT5000 Gasmet logo
  • T500U CAPS NO2 web
  • T100U SO2 web
  • Gasmet black-2
  • opsis DOAS
  • Lephalale

Opsis was founded in 1985 when two Ph.D. students from the University of Lund, Sweden, took the concept of measuring gases with light and developed it into a commercially viable product. Svante Wallin and Leif Unéus developed the idea of measuring gases in air, by using light. This technology also made it possible to measure several gases simultaneously, using one analyser.

Opsis is certified according to ISO 9001 quality system and ISO 14001 environmental quality system.

The Opsis analyser systems use the DOAS (Differential Optical Absorption Spectroscopy) technique. In addition, Opsis offers a wide range of additional equipment such as compact analysers, Oxygen meters and particulate monitors. Opsis have also developed powerful software tools for environmental management.

In addition to the above-mentioned gas analysers, Opsis also distribute the SM200 Particulate monitor, which has recently been designated as a reference level particulate sampler by TUV.

What is DOAS?

In the DOAS systems developed by Opsis, an emitter projects a beam of light to a receiver. The light is transferred to the analyser through a fibre optic cable. Here, specific gases will absorb light from known parts of the light spectrum, in UV, visible and IR wavelengths. The absorption is recorded using a computer-controlled spectrometer. The computer also logs the results for immediate display or for future analysis.

This technology is the same for both ambient open-path systems, as well as for stack applications. A variety of fibre optic cables are available, and the type is determined by the application, the gases being measured, as well as the type of analyser (UV or IR).

Schematic of the Opsis DOAS technique Opsis AQM application Opsis CEM application AQM stations

What can be measured by the Opsis DOAS systems?


Bromine (Br2)

Hydrogen cyanide (CHN)

Chlorine (Cl2)

Chlorine dioxide (ClO2)

Carbon monoxide (CO)

Carbon dioxide (CO2)

Phosgene (COCl2)

Carbon disulphide (CS2)

Water vapour (H20)

Hydrogen sulphide (H2S)

Hydrogen bromide (HBr)

Hydrogen chloride (HCI)

Hydrogen cyanide (HCN)

Hydrogen fluoride (HF)

Mercury (Hg)

Nitrous acid (HNO2)

Nitrous oxide (N2O)

Ammonia (NH3)

Nitric monoxide (NO)

Nitrogen dioxide (NO2)

Nitrate radical (NO3)

Oxygen (O2)

Ozone (O3)

Sulphur dioxide (SO2)

Sulphur trioxide (SO3)



Naftalene (C10H8)

Acethylene (C2H2)

Ethene (C2H4)

Acetaldehyde (C2H4O)

Ethane (C2H6)

Ethanol (C2H6O)

Propane (C3H8)

Trimethylbenzene (C6H3(CH3)3)

o-,m-,p-Xylene (C6H4(CH3)2)

Ethylbenzene (C6H5C2H5)

Styrene (C6H5CH=CH2)

Phenol (C6H5OH)

Benzene (C6H6)

Toluene (C7H8)

Formaldehyde (CH2O)

o-,m-,p-Cresol (CH3C2H4OH)

Methane (CH4)

Methanol (CH4O)

Total hydrocarbons (THC)

This list is continuously expanding to include more compounds.

Opsis applications

Opsis equipment can be found in a wide variety of applications in the fields of ambient air quality, continuous emission monitoring as well as process control. In addition to monitoring equipment, Opsis also distributes a complete data management system. Due to space constraints, we cannot include all the information here, but feel free to use the links to view the information on the Opsis website. Some application case studies covering the applications listed below, can be downloaded from the Press page.

Ambient air quality monitoring applications using the Opsis-developed equipment, can be classified into the following areas:

Continuous emission monitoring applications using the Opsis-developed equipment, has been successfully applied in a variety of industries. This list is continuously growing as Opsis and its network of distributors install the Opsis range of equipment on a wider range of industrial sites and processes. These industries include, but are not limited to:

The Opsis system as monitoring solution, is particularly well suited to process control. As such, international installations exist in all the CEM fields listed above, where the Opsis DOAS in conjunction with ancillary equipment, is being used purely for process control purposes.

The range of Opsis equipment is crowned by an equally impressive data management package. The data management package is a real-time data management system, that includes:

  • Collection, validation and storage of data

  • Exporting and reporting of collected data

  • Advanced statistical analysis and comparison

  • GIS system for comprehensive environmental modelling

  • Ability to integrate data from a variety of external sensors and instruments

  • Can handle analogue and digital input/output signals as well as serial communication

  • Software package that meets the EC regulations for reporting.


Are there any international approvals for the Opsis range of equipment?

The short answer is YES. Opsis holds several international approvals for their systems. As these approvals are too many to list here, please feel free to follow the link to their website where you can browse through the various international approvals at your leisure.