Abstract: According to an example aspect of the present invention, there is provided an apparatus comprising a normalized surface condition monitoring sensor, and a processing unit comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to process surface data based on a real time position of the apparatus to obtain calibration of the surface condition monitoring sensor, wherein values of the surface data originate from at least one normalized surface condition monitoring system, and wherein at least some of the values of the surface data are associated with position information.

Abstract: A method and apparatus for calibrating an optical surface condition monitoring system (1). Light beams at different wavelengths (?1, ?2) are emitted to a reference substrate (2) at different distances (L1, L2) as well as to sample substrates (5) at a specific distance (Lspecific). Subsequently, ratios between the signals scattered back from the reference substrate (2) and the signals scattered back from the sample substrates (5) are calculated. Then, input data regarding a measurement distance (Lmeasurement) between a target surface (8) to be monitored, for example a road, and the receiver (3) of the system (1) is provided. Further, a preset program is selected. Dry calibration of the system (1) can then take place based on the calculated ratios, the measurement distance (Lmeasurement) and the selected program. Dry calibration can be calculated without having to perform an actual dry calibration in the field and no dry calibration plate or dry spot of the target surface (8) is required.

Abstract: A method for improving optical measurement of gas concentration includes steps for directing narrow band light to the gas to be measured and measuring the attenuation of the light in the gas, modulating the center wavelength of the light source around or over a first predetermined absorption maximum (absorption line) of the measured gas and aside of it, measuring the attenuation of the light in the gas as a function of the center wavelength of the light, and determining the gas concentration based on the measurement. The center wavelength of the light is varied such that the center wavelength is adapted to coincide with at least one other absorption maximum (peak) with different absorption properties of the gas to be measured, and correspondingly the attenuation of the other absorption maximum or maxima is measured as a function of the center wavelength of the light.

Abstract: The present invention relates to a method for improving optical measurement of gas concentration. The method comprises steps for directing narrow band light to the gas to be measured and measuring the attenuation of the light in the gas, modulating the center wavelength of the light source around or over a first predetermined absorption maximum (10) (absorption line) of the measured gas and aside of it, measuring the attenuation of the light in the gas as a function of the center wavelength of the light, and determining the gas concentration based on the measurement. According to the invention the center wavelength of the light is varied such that the center wavelength is adapted to coincide with at least one other absorption maximum (11) (peak) with different absorption properties of the gas to be measured, and correspondingly the attenuation of the other absorption maximum or maxima is measured as a function of the center wavelength of the light.