Striped optical filters (cyan, magenta and yellow) are fabricated using a multi-target RF sputtering apparatus. These filters are made of 13 layers of TiO2 and SiO2, with refractive indices of 2.50 and 1.47, respectively, at 546.1 nm. The spectra for these filters do not shift more than ±2 nm after baking at 500°C for 1 h in air. The filter layers are deposited alternately in one pump-down vacuum. The pitch, length and number of stripes are 20 micro m, 10 mm and about 700 lines respectively. The stripes are photoetched with conventional lift-off techniques, using two layers of Al and Cr. Each layer is deposited by placing the substrate holder under the TiO2 and SiO2 target for appropriate time intervals calculated from the deposition rate. Deviations in the deposition rate are within ±2%, as the result of automatically controlling RF power and sputtering gas pressure. The electric signal output from each color channel of these striped filters in tri-electrode pickup tube is increased by 6 dB over that of conventional R, G and B filters. The related moiré signal-to-noise ratio has been decreased by 6 dB. © 1979.
