METHODS AND APPARATUS FOR PROVIDING AN ABSORBING, BROAD BAND, LOW BRIGHTNESS ANTIREFLECTION COATING

The present invention relates to electrically-conductive, absorbing, contrast-enhancing antireflection coatings having excellent optical properties characterized by, specifically, a large bandwidth ratio, i.e., a ratio indicative of the range of wavelengths for which the reflectance value is less than 0.6%, and a small brightness value for the visible wavelengths. It has been surprisingly discovered that a simple, two-layer substrate coating consisting of only a first thin layer of a transparent material having a low refractive index and a second very thin layer of an absorbing, electrically conductive, transition metal oxynitride material provides high performance, electrically conductive, contrast-enhancing antireflection coatings having small brightness values and large bandwidth ratios. The present invention provides antireflection coatings having brightness values less than or equal to about 0.22, and preferably less than or equal to about 0.15. One important advantage of the present invention is that, due to the simplicity of the design and the suitability and efficiency of deposition of the materials in an in-line DC reactive magnetron sputtering process, the high performance, absorbing, electrically conductive, and contrast-enhancing antireflection coatings in accord with the present invention can be produced in a very cost-effective manner.