Optical device using laterally-shiftable diffraction gratings
AssigneesThe Trustees of the University of Pennsylvania, Toyota Motor Engineering & Manufacturing North America, Inc.
InventorsHideo IIZUKA, Nader ENGHETA
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Abstract
A double-sided grating divider acts as a light switch where the upper and lower grating dividers are arranged to accommodate a relative lateral shift therebetween of about one-fourth of the period of the diffraction grating elements and where the critical refraction angles of the grating dividers are more than about 43.6°. Lateral shift may be achieved by various devices including MEMS and metal couplers having a known/calibrated thermal coefficient of expansion over a temperature range of interest.
Claims21
An optical device comprising:
- first and second substantially identical diffraction grating dividers each having a distributed plurality of grating elements;
- said grating dividers being arranged in mutually inverted but spaced apart and substantially aligned relationship;
- and
- means for varying the lateral alignment of the first and second grating dividers relative to one another to vary the degree to which incident light is transmitted therethrough.
A light valve comprising:
- first and second substantially identical diffraction grating dividers each made up of a distributed plurality of grating elements having predetermined, regular geometries and formed of a first material;
- said gratings being arranged in mutually inverted relationship;
- one side of the first grating divider providing an input to incident light, the opposite another side of the second grating divider opposite said one side providing an output to transmitted light;
- and
- the elements of first and second grating dividers being arranged to permit variations in lateral alignment which variations vary the transmission of light through said gratings.
A variably light-transmissive window comprising:
- first and second diffraction grating dividers each made up of a distributed plurality of grating elements having regular geometries and formed of a first material carried by a substrate of a second material wherein the geometries of said grating elements are substantially identical;
- said grating dividers being arranged in mutually inverted, substantially laterally aligned, spaced-apart relationship with an interface substance having a refraction index of about 1 therebetween;
- a first side of the first grating divider providing an input surface to incident light, a first side of the second grating divider providing an output surface to transmitted light;
- and
- means for varying the lateral alignment between the elements of first and second grating dividers thereby to vary the transmission of visible light through said gratings.
A light valve comprising:
- first and second diffraction gratings comprising periodically arranged elements of a first refractive index carried by a substrate of a second refractive index less than the first refractive index;
- the elements of said gratings being of common periodicity;
- a liquid medium;
- said gratings being arranged in use in opposed and aligned relationship with said liquid medium therebetween;
- and
- means for means for changing the alignment between said gratings thereby to vary the transmission of incident polarized light through the valve.
Dependencies are inferred from the claim text.