An optical method for measuring the thickness of heterogeneous materials has been studied. The method is based on the light attenuation theory. A complete system has been constructed in order to demonstrate the applicability of the present method for industrial use. The experimental setup consists of semiconductor lasers, focusing lenses, photo-diodes serving as a power meter and a personal computer with an AID converter for data acquisition. Averaging of numerous measurements is required in the present method because the heterogeneous cell

A system for real-time monitoring of a dye has been constructed which enables us to measure the concentration and fluctuations of the three base colours. The method is based on light attenuation theory and its principle requires three different lasers having the three base colours. The system consisted of a semiconductor laser and argon ion laser for light sources, a photodiode for a light detector and a personal computer for data processing. Detection sensitivity for the dye concentration was a few mg I I and the system can be applied for practical uses.

A real-time measuring method of a dispersive dye, i.e. oil dye, has been developed which enables us to measure the concentration and its fluctuation of the three base colours. The method is based on the light scattering theory and its principle requires three different lasers having the three base colours. The system consisted of a semiconductor laser and argon ion laser for light sources, a photodiode for a light detector and a personal computer for data processing. Detection sensitivity for the dye concentration was about 1 mg I l and was applicable for practical use.