Broad-band antireflection coating having four sputtered layers
AssigneeThe BOC Group, Inc.
InventorsRonald E. Laird, Charles K. Carniglia
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Abstract
A broad-band multilayer antireflection coating comprising four layers designed for deposition in an inline magnetron sputtering machine. The optical thickness of the third layer from the substrate is less than one quarter of a wavelength in the center of the low-reflection band, and the second and fourth layers are made of silicon dioxide.
Claims51
An antireflection coating for a transparent or semi-transparent substrate consisting essentially of four optical interference layers, the coating comprising:
- a first layer adjacent to the substrate having a refractive index greater than about 1.9;
- a second layer comprising silicon dioxide or silicon dioxide doped with less than 20% of another material;
- a third layer having a refractive index greater than about 2.1 and an optical thickness less than .lambda..sub.0 /4, where .lambda..sub.0 is a central wavelength corresponding to a spectral region bounded by or in the visible spectrum;
- and
- a fourth layer comprising silicon dioxide or silicon dioxide doped with less than 20% of another material.
An antireflection coating for a transparent or semi-transparent substrate consisting essentially of four optical interference layers, the coating comprising:
- a first layer adjacent to the substrate having a refractive index greater than about 1.9;
- a second layer having a refractive index less than that of the first layer;
- a third layer having a different composition than the first layer, the third layer having a refractive index greater than about 2.1 and greater than the refractive index of the first layer and an optical thickness less than .lambda..sub.0 /4, where .lambda..sub.0 is a central wavelength corresponding to a spectral region bounded by or in the visible spectrum;
- and
- a fourth layer having a refractive index less than that of the first layer.
An antireflection coating for a transparent or semi-transparent substrate consisting essentially of four optical interference layers, the coating comprising:
- a first layer adjacent to the substrate having a refractive index greater than about 1.9;
- a second layer having a refractive index less than that of the first layer;
- a third layer having a refractive index greater than about 2.1 and an optical thickness less than .lambda..sub.0 /4, where .lambda..sub.0 4 is a central wavelength corresponding to a spectral region bounded by or in the visible spectrum;
- a fourth layer having a refractive index less than that of the first layer;
- and
- an absorbing layer adjacent to the third layer.
Dependencies are inferred from the claim text.