Fiber-Optic Colorimeter

The paper presents construction of a simple fibre-optic color sensor designed for recognition of objects from a set comprising an "a prori" defined, limited number of colors. Hereby, color recognition is understood as distinguishing among colored objects and defining theirs colors, but is not exactly the color measurement because it is not subjected to any standardization. The device operation is therefore close to machine color vision. The construction was assumed to be simple and low-cost, therefore using standard, cheap optoelectronic elements. Color sensing is based on the diffusive reflectivity of the examined surfaces measured in several separate spectral channels. Number and positions of channels depend on predetermined set of colors. The channels are fed by selected LEDs sequentially in TDMA-mode. Collected serially analogue signals are converted onto digital data enabling some processing variants.