Three-dimensional Distribution of Ink-jet Inks in Paper Acquired by Confocal Laser Scanning Microscope

A new method of determining three-dimensional distribution of dyed inks for ink-jet was demonstrated. In this method, fluorescence emitted from dyes is detected in a laser scanning microscope. Most magenta and black dyed inks for ink-jet contain fluorescence agents or use fluorescence dyes specific of the colour. Fluorescence emitted from those of the ink-jet inks provides a three dimensional ink distribution by the optical slicing function of a confocal laser scanning microscope. Its characteristic high sensitivity owes to intense light emission even from trace fluorescence dyes as compared to observation with a regular optical microscope. However, it keeps easy sample preparation, as is a merit of optical microscopy. In applications, several facts were revealed. Ink dot shape was like a coin with a constant thickness on photo quality paper, ink spreads over crack surfaces on high gloss type paper a few times deeper than the normal penetration and ink dots had rugged edges with their tips intruding between fibers in the base paper for medium grade paper. Three-dimensional image analysis is potential to be a useful measure to clarify more dyed ink penetration mechanisms.