Dielectric micro-filter arrays for local resolving color sensors

Two different types of color sensor have been developed, which are adaptable to a wide variety of industrial applications. One kind of sensor was developed by depositing dielectric interference filters directly on photoelectric cells, applying a low temperature coating procedure. This way it was possible to accommodate spectral characteristics to the specific spectral sensitivity of the photoelectric cells, minimizing losses by absorption and scattered light in the desired spectral region. The geometric shape of these coated cells is suitable especially for color measurements using fibers. The second kind of color sensors, consisting of miniaturized photoelectric cell arrays and three different micro-patterned interference filter arrays, arranged on a glass substrate, make it possible to distinguish and measure colors with a local resolution. The honey-comb-arrangement of filter- and receiver cells and a flexible setup also permits a fast adaptation to different applications. In this p aper design and development of both miniaturized interference filers are described. The different manufacturing procedures are depicted, advantages and questions arising with the employment of interference filters are discussed and the entire assembly of both sensors is presented.