Abstract: In accordance with an example aspect of the present invention, there is provided a method of obtaining a calibrated measurement of a sample using an integrating cavity, comprising obtaining sample spectral information by using the integrating cavity with the sample placed inside the integrating cavity, obtaining cavity-characterizing spectral information generated by using the integrating cavity with a standard object, and obtaining a measurement result from the sample spectral information by employing a mathematical process that takes the cavity-characterizing spectral information as input.

Abstract: Optical analyzer (10,50,60) comprises an optically integrating cavity (20), the optically integrating cavity (20) formed by at least one optical light diffusing wall (31) and adapted to contain a sample of a solid agricultural product, the sample consisting of one or more sample elements (41,48), a light source (13,33), emitting light into the optically integrating cavity (20), whereas the at least one optical light diffusing wall (31) is utilized to convert emitted light to diffused light, whereas the sample at least partially or completely converts the diffused light to spectrally filtered light, and a spectral sensor (26). The sample is confined in the optically integrating cavity (20) while the spectral sensor (26) is being exposed to the spectrally filtered light. Patent application has independent claims also for optical analyzing method and sample preparation device.