Gas Concentration Units and Unit Conversions Bengt Löfstedt General, AQM, CEM 2023-05-11 View Count 1399 On the most fundamental level, the signal from the sensor of a gas analyser gives the number of gas molecules, usually along an optical light beam or in a certain sampling volume. However, a concentration should not be expressed in number of molecules – the number would be far too big. Instead, it is scaled to a unit of weight-per-cubic-metre or volumetric share. How is the scaling done? Read More »
Uncertainties in Measurements Bengt Löfstedt General, AQM, CEM 2023-04-20 View Count 886 With all efforts made on precision instrumentation, quality assurance, calibrations, parallel measurements, and adjustments, the measurement results produced by a gas monitor should be spot on, right? Well, not quite… Read More »
Instrument Interfaces Bengt Löfstedt AQM, CEM, General 2023-04-06 View Count 658 A lot of efforts are usually spent on gas concentration measurements and making sure that the measurements are correct. However, all that is of little value if the resulting data is not available. Here is where the instrument interfaces come in play. Read More »
Spring is in the Air Bengt Löfstedt General 2023-03-16 View Count 1172 At the home of OPSIS, the phrase ‘spring is in the air’ is an established saying which means long-awaited warmer and longer days and the sense of a new beginning. But what’s in the air in the spring, really? Let’s take a look at seasonal variations of air pollution! Read More »
Good Averages, on Average? Bengt Löfstedt General 2023-03-13 View Count 810 We all know how to calculate the average of a set of values: add the individual values and then divide by the number of them. Right? Yes, almost always right, but if you work with air quality and specifically meteorological data, you must sometimes think a little further. Read More »
Keep an Eye on Ozone Bengt Löfstedt General, AQM 2022-09-16 View Count 6243 Stratospheric ozone is a blessing. It prevents most of the sun’s ultraviolet radiation from reaching the surface of the earth, and thereby protects surface-dwelling life from damaging UV rays. At the same time, ground-level ozone is a major air pollutant. Let’s take a closer look at the latter phenomenon. Read More »
Inside the Gas Analyser – the Tuneable Diode Laser Bengt Löfstedt General 2021-04-08 View Count 12598 OPSIS is probably best known for its gas analyser systems based on broad-band (“white”) light from xenon lamps and spectrometers or interferometers as the core analysis devices. However, OPSIS also offers an instrument type base on a quite different optical technique – light absorption detected by utilizing a tuneable diode laser. Let’s take a closer look! Read More »
Inside the Gas Analyser – the Interferometer Bengt Löfstedt General 2021-03-16 View Count 3599 Some OPSIS gas analysers are based on a device called an interferometer. Like a spectrometer, it separates light into its wavelength components, but it’s done in a special and indirect way. Keep on reading to find out how! Read More »
Inside the Gas Analyser – the Spectrometer Bengt Löfstedt General 2021-02-23 View Count 4459 Several of OPSIS gas analyser types are based on a device called a spectrometer. It separates light into its wavelength components, allowing the analyser to detect light absorption and thereby determine gas concentrations. Let’s take a closer look at how a spectrometer works! Read More »
Once Upon a Time – the Founding of OPSIS Bengt Löfstedt General 2020-12-17 View Count 3971 In 2020, OPSIS has been in the gas monitoring business for 35 years. How did it all start, and what does “OPSIS” actually mean? Read on to find out! Read More »