Correction of fluorescence attenuation with depth in fibre and paper images collected by confocal laser scanning microscopy

An empirical method is proposed to compensate for the attenuation of the de tected fluorescence signal with depth in the images collected using a confo cal laser scanning microscope. Application of this method to cross-sections of wood fibres or paper sheets is described. The method is based on fittin g a curve to the experimental intensity versus depth data for each cross-se ction image. The compensation index is calculated from the fitted function and a compensated image is computed. The new fibre image has uniform contra st with depth, providing easier assessment of fibre cross-sections. Images of paper sheets, modified using the compensation technique, show structures to a depth of up to 80 mu m including details at a depth which could not b e seen in the original images.