Abstract: A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser, which dielectric material is coated with a thin layer of a material absorptive for light of the frequency supplied by the recording laser (e.g., titanium). The coating parameters are chosen to establish an anti-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated. With the peak intensity of the focused light sufficient to at least cause melting of the absorptive layer, an information track is formed as a succession of spaced pits in which the reflective layer is effectively exposed through the layer of dielectric material.

Abstract: A flat major surface of a disc-shaped substrate (e.g., of glass) is coated with a light-reflective layer (e.g., of aluminum) which is coated with a dielectric material (e.g., silicon dioxide) highly transparent for light of a frequency supplied by a recording laser and of a thickness equal to an integer multiple of the half-wavelength of the laser light output in the dielectric material. The dielectric material is coated with a layer of material moderately absorptive for light of the frequency supplied by the recording laser (e.g., an organic dye such as fluorescein). The coating parameters are chosen to establish an anti-reflection condition for the coated record blank at the recording light frequency. The light output of the laser, which is intensity modulated in accordance with a signal to be recorded, is focused upon the coated surface of the disc as the disc is rotated.

Abstract: An optical record blank structure comprises a disc-shaped substrate (e.g., glass), a layer of light-reflective material (e.g., aluminum) overlying a surface of the disc-shaped substrate, a coating of a transparent material (e.g., silicon dioxide) overlying the light-reflective layer and a coating of a moderately absorptive material (e.g., an organic dye such as fluorescein) overlying the dielectric coating. The coating parameters are chosen to establish an antireflective condition to a recording light beam incident on the disc surface. The transparent coating thickness is selected such that the transparent coating is optically passive to the recording light beam, i.e., the thickness of the transparent coating is selected to be an integer multiple of the half-wavelength of the recording light beam wavelength in the transparent material.

Abstract: Playback apparatus, providing a playback beam of light, effects signal recovery, from an information record, with a high signal-to-noise ratio. An information record, suitable for use with such playback apparatus, comprises a flat major surface of a disc-shaped foundation coated with a layer of a thermally conductive material overlaid with a layer of a thermally insulating material. Information storage is effected in a layer of material (e.g., platinum-cobalt), highly absorptive for light of a frequency supplied by a recording laser, which layer overlies the insulating layer. By proper choice of thicknesses for the insulating and the conductive layers, absorptive layer sensitivity to the intensity of the playback beam of lights is effectively reduced to enable record playback at high playback beam intensity levels without damage thereto. Where the foundation is formed of a thermally conductive material, the layer of thermally conductive material may be dispensed with.

Abstract: A photovoltaic device has a body which includes a thin film active region and a layer substantially transparent to solar radiation. The thickness of the transparent layer is such that a first antireflection condition is present for solar radiation at a wavelength which is relatively highly absorbed by the material of the active region. Furthermore, the combined thickness of the transparent layer and active region are such that a second antireflection condition is present for solar radiation at a wavelength which is poorly absorbed by the material of the active region. As a result of the prevailing antireflection conditions the solar radiation absorption efficiency of the photovoltaic device is increased.