Optical film with sharpened bandedge

• US 20050243425A1
• Filed: 07/01/2005
• Published: 11/03/2005
• Est. Priority Date: 01/13/1998
• Status: Abandoned Application

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Wheatley, John A., Weber, Michael F., Ouderkirk, Andrew J.
• Application Number:
  US11/173,663
• Publication Number:
  US 20050243425A1
• Time in Patent Office: Days
• US Class Current: 359/589
• CPC Class Codes: G02B 5/282 reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
• CPC Class Codes: G02B 5/287 comprising at least one layer of organic material
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers

Abstract

The present invention provides reflective films and other optical bodies which exhibit sharp bandedges on one or both sides of the main reflection bands. The optical bodies comprise multilayer stacks M₁ and M₂, each having first order reflections in a desired part of the spectrum and comprising optical repeating units R₁ and R₂, respectively. At least one of the optical repeating units R₁ and R₂ varies monotonically in optical thickness along the thickness of the associated multilayer stack.

Claims

1. A reflective film comprising a plurality of optical repeating units having an optical thickness profile that defines a curve, the curve having substantially no discontinuities in its first derivative and shaped so that it, in order, monotonically decreases from an initial optical thickness to a minimum optical thickness, remains substantially constant at the minimum optical thickness, monotonically increases from the minimum optical thickness to a maximum optical thickness, remains substantially constant at the maximum optical thickness, and monotonically decreases from the maximum optical thickness to an end optical thickness, wherein the optical repeating units monotonically increasing from the minimum optical thickness to the maximum optical thickness form a reflection band.

2. The reflective film of claim 1, wherein the reflection band includes visible light.

3. The reflective film of claim 1, wherein the reflection band includes infrared light.

4. The reflective film of claim 1, wherein the reflection band includes ultraviolet light.

5. The reflective film of claim 1, wherein the optical repeating units comprise polymer layers.

6. The reflective film of claim 1, wherein the optical repeating units comprise a plurality of layers.

7. The reflective film of claim 5, wherein at least a portion of the optical repeating units comprise two layers.

8. The reflective film of claim 5, wherein at least a portion of the optical repeating units comprise three layers A, B, and C arranged in an order ABC, the layers having respective indices of refraction n^a, n^b, and n^c that differ from each other, index n^b being intermediate to indices n^a and n^c.

9. The reflective film of claim 8, wherein the three layers are arranged in an order ABCB.