Spectra-physics Visiontech Oy

Mika Christophliemk

Heimo Keranen

A calibration method especially for calibrating a reflection spectrometric gauge, such as an oil film gauge. In the method, calibration is conducted by measuring the gauge response by means of a calibration unit and a solid, stable permanent sample (37) provided on it as a calibration sample. A change that simulates a certain substance concentration is generated by the stable permanent sample (37) in the reflection spectrum, and the gauge response is calibrated on the basis thereof. In the invention, the gauge response is calibrated by using at least two calibration samples (37, 39) having different absorption responses, said two calibration samples being said permanent sample (37) and a second calibration sample (39). For calibration, roughness compensation is performed, in which the gauge response is corrected on the basis of the measurement of the optical response of the surface to be measured and the known data on roughness dependence.

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Oulu, Finland

Mika Christophliemk