Omnidirectional reflector

• US 9,063,291 B2
• Filed: 02/05/2011
• Issued: 06/23/2015
• Est. Priority Date: 08/12/2007
• Status: Active Grant

• Current Assignee: Toyota Motor Corporation
• Original Assignee: Toyota Motor Corporation, Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Banerjee, Debasish, Zhang, Minjuan, Ishii, Masahiko
• Primary Examiner(s): Chang, Audrey Y
• Application Number:
  US13/021,730
• Publication Number:
  US 20110128616A1
• Time in Patent Office: 1,599 Days
• Field of Search: 359/585, 359/586, 359/587, 359/588, 359/589, 359/359, 359/360, 359/584, 257/98, 428/403, 428/446, 428/412
• US Class Current: 1/1
• CPC Class Codes: G02B 5/0825 the reflecting layers comprising dielectric materials only
• CPC Class Codes: G02B 5/085 at least one of the reflecting layers comprising metal
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361

Abstract

An omnidirectional structural color (OSC) having a non-periodic layered structure. The OSC can include a multilayer stack that has an outer surface and at least two layers. The at least two layers can include at least one first index of refraction material layer A1 and at least one second index of refraction material layer B1. The at least A1 and B1 can be alternately stacked on top of each other with each layer having a predefined thickness d_A1 and d_B1, respectively. The d_A1 is not generally equal to the d_B1 such that the multilayer stack has a non-periodic layered structure.

Claims

1. An omnidirectional structural color (OSC) having a non-periodic layered structure, said OSC comprising:

a multilayer stack having an outer surface and at least five layers, said at least five layers having at least two first index of refraction oxide material layers A1 and A2, at least two second index of refraction oxide material layers B1 and B2, said at least two layers A1 and A2 and at least two layers B1 and B2 alternately stacked on top of each other;

said at least A1, A2, B1 and B2 layers having a predefined thickness of d_A1, d_A2, d_B1 and d_B2, with said d_A1 thickness not generally equal to said d_A2, d_B1 or said d_B2 thickness such that said multilayer stack has a non-periodic layered structure; and

said multilayer stack defining a reflector, said reflector having a single first reflection band with a center wavelength in the visible light spectrum, said single first reflection band being a reflectance of more than 50% of said center wavelength of a band of reflected electromagnetic radiation, said first reflection band also having a full width at half maximum (FWHM) of less than 200 nanometers and a shift of said center wavelength of less than 50 nanometers when said outer surface is exposed to a generally broad band of electromagnetic radiation at angles between 0 and 45 degrees with respect to the normal of said outer surface.

2. The OSC of claim 1, further comprising at least one third index of refraction material layer C1 having a predefined thickness d_C1, said at least two layers A1 and A2 and said at least two layers B1 and B2 alternately stacked on top of each other and on top of said C1 layer and said d_C1 thickness not generally equal to said d_A1 or d_A2 thickness.

3. The OSC of claim 2, wherein said band of reflected electromagnetic radiation has a FWHM of less than 100 nanometers.

4. The OSC of claim 2, wherein said multilayer stack has a second reflection band, said second reflection band being a reflectance of more than 50% of ultraviolet electromagnetic radiation having a center wavelength of less than 400 nanometers.

5. The OSC of claim 2, wherein said A1, A2, B1, B2 and C1 layers are selected from a group consisting of titania, silica, mica, zirconium oxide, niobium oxide, chromium and silver.

6. A process for omnidirectionally reflecting a band of electromagnetic radiation, the process comprising:

providing a multilayer stack having an outer surface and at least five layers, the at least five layers having at least two first index of refraction oxide material layers A1 and A2, at least two second index of refraction oxide material layers B1 and B2, the at least two layers A1 and A2 and at least two layers B1 and B2 alternately stacked on top of each other;

the at least A1, A2, B1 and B2 layers having a predefined thickness of d_A1, d_A2, d_B1 and d_B2, with the d_A1 thickness not generally equal to the d_A2, d_B1 or d_B2 thickness such that the multilayer stack has a non-periodic layered structure and defines a reflector; and

providing a source of broadband electromagnetic radiation;

exposing the multilayer stack to the broad band electromagnetic radiation at angles between 0 and 45 degrees with respect to the normal of the outer surface; and

the reflector reflecting a single first reflection band with a center wavelength in the visible light spectrum, the single first reflection band being a reflectance of more than 50% of the center wavelength of a band of reflected electromagnetic radiation, the single first reflection band also having a full width at half maximum (FWHM) of less than 200 nanometers wide and a shift of the center wavelength of less than 50 nanometers when an outer surface of the multilayer stack is exposed to the generally broad band of electromagnetic radiation at angles between 0 and 45 degrees with respect to the normal of the outer surface.

7. The process of claim 6, further comprising the multilayer stack having at least one third index of refraction material layer C1 having a predefined thickness d_C1 not equal to the d_A1 or d_A2 thickness, the at least two layers A1 and A2 and the at least two layers B1 and B2 alternately stacked on top of each other and on top of the C1 layer.

8. The process of claim 7, further comprising the reflector reflecting a second reflection band in the ultraviolet electromagnetic radiation spectrum, the second reflection band having a center wavelength of less than 400 nanometers and being a reflection of more than 50% of the center wavelength.

9. The process of claim 7, wherein A1, B1 and C1 are selected from a group consisting of titania, silica, mica, zirconium oxide, niobium oxide, chromium and silver.