three layer anti-reflective coating for optical substrate
AssigneeNikon Corporation
InventorTakeshi Shirai
Life of this patent
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Abstract
Anti-reflective coatings for use on an optical substrate are disclosed having a low reflectance over a broad band of wavelengths in the ultraviolet range and exhibiting excellent "laser durability." The anti-reflective coatings comprise a layer of high-refractive index material situated between at least two layers of low-refractive index material. The layers of high- and low-refractive index material are laminated onto an optical substrate, such as glass or quartz. The anti-reflective coating minimizes the loss of light due to flares, ghosts, etc. Additionally, reflections are reduced over a broad range of incidence angles.
Claims16
An optical element, comprising:
- (a) an optical substrate;
- (b) at most three layers of low- and high-refractive index material laminated on a surface of the optical substrate, the three layers comprising a layer of high-refractive index material situated between first and second layers of low-refractive index material;
- (c) the first low-refractive index layer being adjacent the optical substrate and having an optical film thickness of (0.05) .lambda..sub.0 to (0.15) .lambda..sub.0 ;
- (d) the high-refractive index layer having an optical film thickness of (0.2) .lambda..sub.0 to (0.35) .lambda..sub.0 ;
- and
- (e) the second low-refractive index layer having an optical film thickness of (0.2) .lambda..sub.0 to (0.3) .lambda..sub.0, wherein .lambda..sub.0 is a design-center wavelength for the optical element and is within a range of 150-300 nm.
An optical element, comprising:
- (a) an optical substrate;
- (b) a first layer of low-refractive index material on a surface of the optical substrate;
- (c) a layer of high-refractive index material superposed on the first layer of low-refractive index material;
- (d) a second layer of low-refractive index material superposed on the layer of high-refractive index material;
- (e) the first layer of low-refractive index material having an optical film thickness of (0.05) .lambda..sub.0 to (0.15) .lambda..sub.0, wherein the optical substrate has at most three layers laminated thereon;
- and .lambda..sub.0 is a design-center wavelength and is within a range of 150-300 nm.
Dependencies are inferred from the claim text.