Omnidirectional UV-IR reflector
The present invention provides an omnidirectional ultraviolet (UV)-infrared (IR) reflector. The omnidirectional UV-IR reflector includes a multilayer stack having at least three layers, the at least three layers having at least one first index of refraction material A 1 and at least one second index of refraction layer B 1 . The at least one first index of refraction material layer and the at least one second index of refraction material layer can be alternately stacked on top of each other to provide the at least three layers. In addition, the at least one first index of refraction material layer and the at least one second index of refraction material layer each have a predefined thickness of d A1 and d B1 , respectively, with the thickness d A1 not being generally equal to the d B1 thickness such that the multilayer stack has a non-periodic layered structure.
1. An omnidirectional UV-IR reflector comprising:
a multilayer stack having an average thickness between 0.5 and 10 microns and between four and thirteen layers, said between four and thirteen layers having at least two first index of refraction material layers H 1 and H 2 , and at least two second index of refraction material layers L 1 and L 2 , said at least two first index of refraction material layers and said at least two second index of refraction material layers alternately stacked on top of each other such that said H 1 layer is located between said L 1 layer and said L 2 layer, and said L 2 layer is located between said H 1 layer and said H 2 layer;
said between four and thirteen layers each having a predefined thickness of d H1 , d H2 , d L1 , d L2 with said d H1 thickness not generally equal to said d H2 thickness and said d L1 thickness not generally equal to said du thickness; and
wherein said multilayer stack when shined by light at incident angles between 0 to 45 degrees, has a first high reflectivity bandwidth with more than 50% reflectance of electromagnetic radiation having wavelengths less than about 400 nanometers, a second high reflectivity bandwidth with more than 80% reflectance of electromagnetic radiation having wavelengths greater than about 800 nanometers, and a low reflectivity bandwidth with less than 20% reflectance of electromagnetic radiation having wavelengths between about 400 nanometers to 800 nanometers.
2. The omnidirectional UV-IR reflector of claim 1 , wherein said first high reflectivity bandwidth has at least 75% reflectance of said electromagnetic radiation having a wavelength of less than about 400 nanometers.
3. The omnidirectional UV-IR reflector of claim 2 , wherein said low reflectivity bandwidth has is greater than 80% transparency for electromagnetic radiation having a wavelength between about 400 to 800 nanometers.
4. The omnidirectional UV-IR reflector of claim 3 , wherein said low reflectivity bandwidth has is greater than 90% transparency for electromagnetic radiation having a wavelength between about 400 to 800 nanometers.
5. The omnidirectional UV-IR reflector of claim 1 , wherein said multilayer stack reflects greater than 80% of electromagnetic radiation having wavelengths between about 800 and 1400 nanometers.
6. A process for omnidirectionally reflecting UV and IR electromagnetic radiation, the process comprising:
providing a multilayer stack having an average thickness between 0.5 and 10 microns and between four and thirteen layers, the between four and thirteen layers having at least two first index of refraction material layers H 1 and H 2 , and at least two second index of refraction layers L 1 and L 2 , the at least two first index of refraction material layers and the at least two second index of refraction material layers alternately stacked on top of each other such that the H 1 layer is located between said L 1 layer and said L 2 layer, and said L 2 layer is located between said H 1 layer and said H 2 layer;
the between four and thirteen layers each having a predefined thickness of d H1 , d H1 , d L1 , d L2 with the d H1 thickness not generally equal to the d H2 thickness and the d L1 thickness not generally equal to the d L2 ;
wherein the multilayer stack when shined by white light at incident angles between 0 to 45 degrees, has a first high reflectivity bandwidth with more than 50% reflectance of electromagnetic radiation having a wavelength of less than about 400 nanometers, a second high reflectivity bandwidth with more than 80% reflectance of electromagnetic radiation having a wavelength of greater than about 800 nanometers, and a low reflectivity bandwidth with less than 20% reflectance of electromagnetic radiation having wavelengths between about 400 nanometers to 800 nanometers;
providing a source of white light;
exposing the multilayer stack to the source of white light; and
the multilayer stack reflecting at least:
50% of electromagnetic radiation from the source of white light having wavelengths less than about 400 nanometers,
at least 80% of electromagnetic radiation from the source of white light having wavelengths greater than about 800 nanometers and
less than 20% of electromagnetic radiation from the source of white light having wavelengths between about 400 nanometers to 800 nanometers.
7. The process of claim 6 , further including reflecting at least 75% of the electromagnetic radiation from the source of white light having wavelengths less than about 400 nanometers.
8. The process of claim 6 , wherein the multilayer stack is transparent to at least 80% of the electromagnetic radiation from the source of white light having a wavelength between about 400 to 800 nanometers.
9. The process of claim 6 , further including reflecting greater than 80% of electromagnetic radiation from the source of white light having wavelengths between about 800 and 1400 nanometers.