Abstract: The present invention relates to a method (1) for determining a content of H2S in a process gas comprising H2S. The method (1) comprises extracting (2) a sample of the process gas, performing oxidation (4) of at least a major portion of H2S of the sample, whereby oxidation products comprising elemental sulfur are formed, analysing (6) the oxidized sample by optical absorption spectroscopy at wavelengths above 310 nm, and determining (8) the content of H2S in the process gas based on the analysing. The invention further relates to a system (100) for determining a content of H2S in a process gas comprising H2S, and use of system (100).

Abstract: Method for titration comprising: providing a solution comprising at least one titrand and at least one indicator; providing a titrant; performing titration by repeatedly: transmitting light through the solution; measuring an intensity of light transmitted through the solution at a first wave length; measuring an intensity of light transmitted through the solution at a second wave length; comparing the measured intensities of light transmitted through the solution at the first and second wave lengths with a target value; and adding titrant to the solution at a rate based on said comparing.

Abstract: A device for radiation absorption measurements may include a radiation source emitting electromagnetic radiation having a wavelength in the interval 0.2 ?m-20 ?m, a detector detecting the electromagnetic radiation, when in a measurement mode at least a portion of the radiation has passed through a medium and been reflected by a surface at a distance from the radiation source, before reaching the detector. The device may further include a fluid calibration cell, which is adapted to be arranged in the path of the electromagnetic radiation between the radiation source and the detector. A method for calibrating a device for radiation absorption measurements may involve emitting electromagnetic radiation having a wavelength in the interval 0.2 to 20 ?m, directing at least a portion of the electromagnetic radiation through a fluid calibration cell, and detecting the electromagnetic radiation.

Abstract: A device for radiation absorption measurements may include a radiation source emitting electromagnetic radiation having a wavelength in the interval 0.2 ?m-20 ?m, a detector detecting the electromagnetic radiation, when in a measurement mode at least a portion of the radiation has passed through a medium and been reflected by a surface at a distance from the radiation source, before reaching the detector. The device may further include a fluid calibration cell, which is adapted to be arranged in the path of the electromagnetic radiation between the radiation source and the detector. A method for calibrating a device for radiation absorption measurements may involve emitting electromagnetic radiation having a wavelength in the interval 0.2 to 20 ?m, directing at least a portion of the electromagnetic radiation through a fluid calibration cell, and detecting the electromagnetic radiation.

Abstract: An interferometer includes a beam splitter (BS) and two scanning mirrors (M1, M2), which are parallel and disposed on a common slide member that can be linearly displaced. The interferometer further comprises two compensating mirrors (M3, M4), which are disposed between the beam splitter (BS) and the scanning mirrors (M1, M2). The beam splitter (BS) and each of the compensating mirrors (M3, M4) are orthogonal. The interferometer has good tolerance for displacement inaccuracies of the scanning mirrors (M1, M2). The interferometer may be used for producing a compact and inexpensive Fourier transform spectrometer.

Abstract: Optical analysing equipment includes a light source, a light receiver and an optical arrangement for producing a measuring beam and a calibrating beam from the light of the light source. A calibrating channel and a measuring channel extend form the light source to the light receiver. The light source and the light receiver can be arranged on opposite sides of the duct. In this case, the calibrating channel and the measuring channel include two tubes extending in parallel across the duct between the light source and the light receiver. The light source and the light receiver can alternatively be arranged on the same side of the duct. In this case, the measuring channel extends partially into the duct. The calibrating channel may then extend into the duct or be positioned entirely outside the duck. By light control means, the light receiver receives either the measuring beam or the calibrating beam.

Abstract: An apparatus for emitting and receiving light comprises an emitter, which consists of a light source (5) and a concave mirror (7), and a receiver which receives light from the emitter and which is connected to analyzing equipment (3). Furthermore, the receiver comprises a concave mirror (9) which is disposed behind the mirror (7) of the emitter and whose diameter is larger than that of the mirror (7) of the emitter and whose focus is located in front of the light source (5). In the focus of the mirror (9) is positioned one end of an optical fibre (19) for transmitting the received light to the analyzing equipment (3).

Abstract: A method for determining parameters, especially pressure, temperature, concentration, number of particles and particle size distribution, of gaseous substances present in combustion processes and other high temperature processes, comprises transmitting spectrally broad-band light through an object (2) of measurement, spectrally dividing the light transmitted through said object, and recording the spectral distribution of the light in the studied wavelength range a large number of times. Each recording occurs sequentially in that the spectrally divided light is swept relative to a one-channel detector and for such a short time that the total light intensity of the entire wavelength range is constant during each recording.