High resolution optical measurement techniques in paper drying

In the scope of this paper, we present the application of three non-invasive optical measurement techniques for the investigation of paper drying process with a high spatial and temporal resolution. These techniques are based on digital image sequence processing with images acquired at different wavelengths ranging from visual to far infrared. Such spectral imaging techniques combine the potential of conventional spectroscopy with the power of digital image processing to characterize the drying with spatial and temporal resolution, thereby making the transient drying of paper visible at different parts of the electromagnetic spectrum. In the present study, three non-invasive optical measurement techniques have been employed for the characterization of local properties and transport phenomena in paper drying at high resolution both in space and time.