Wide angle mirror system
Assignee3M Innovative Properties Company
InventorMichael F. Weber
Life of this patent
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Abstract
Composite mirror systems include a wideband thin film interference stack having a plurality of microlayers and an optically thick layer having a refractive index greater than air but less than the smallest refractive index of the stack. The mirror systems can provide high reflectivity for light propagating in the stack and in the optically thick layer at supercritical angles, while avoiding degradation in reflectivity if dirt or other disturbances such as absorbing materials are present at the mirror backside for example due to contact with a support structure.
Claims13
1 An optical system, comprising:
- a light source;
- and
- a light guide, comprising;
- a plurality of microlayers having refractive indices and thicknesses selected to substantially reflect light over a wavelength range of interest and over an angular range of interest;
- and
- an optically thick layer optically coupled to the plurality of microlayers along a first major surface of the optically thick layer and having a side surface facing the light source for receiving light from the light source.
The optical system of claim 1, wherein the plurality of microlayers includes at least tens of microlayers.
The optical system of claim 1, wherein the plurality of microlayers includes at least hundreds of microlayers.
The optical system of claim 1, wherein the optically thick layer has a refractive index no less than the refractive indices of the microlayers.
The optical system of claim 1, wherein the wavelength range of interest is from 400 nm to 700 nm.
The optical system of claim 1, wherein the optically thick layer has an optical thickness that is on the order of an average wavelength in the wavelength range of interest.
The optical system of claim 1, wherein the optically thick layer has an optical thickness that is at least 10 times an average wavelength in the wavelength range of interest.
The optical system of claim 1 further comprising a liquid crystal panel for receiving light extracted from the optically thick layer along a second major surface opposing the first major surface.
The optical system of claim 1, wherein the light guide is made by a co-extrusion process.
An optical construction, comprising:
- a plurality of microlayers;
- and
- a light guide optically coupled to and coextruded with the plurality of microlayers and comprising light extraction features on a major surface of the light guide for extracting light that is injected into the light guide from a side surface of the light guide.
Dependencies are inferred from the claim text.