Optical film with sharpened bandedge

• US 6,967,778 B1
• Filed: 08/09/2000
• Issued: 11/22/2005
• Est. Priority Date: 01/13/1998
• Status: Expired due to Term

• 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.
• Primary Examiner(s): Chang, Audrey
• Application Number:
  US09/634,319
• Time in Patent Office: 1,931 Days
• Field of Search: 359/584, 359/580, 359/586, 359/588, 359/589, 359/590
• US Class Current: 359/580
• CPC Class Codes: G02B 5/28 Interference filters

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, wherein the optical repeating units vary in optical thickness to form an optical thickness profile that remains substantially constant over a plurality optical repeating units at a first optical thickness near one surface of the film, and that monotonically varies from the first optical thickness to a second optical thickness through a central portion of the film to define a reflection band.

2. The reflective film of claim 1, wherein the film is polymeric.

3. The reflective film of claim 1, wherein the first optical thickness is lower than the second optical thickness.

4. The reflective film of claim 1, wherein the first optical thickness is higher than the second optical thickness.

5. A reflective film comprising a plurality of optical repeating units, wherein the optical repeating units vary in optical thickness to form an overall optical thickness profile that remains substantially constant over a plurality of optical repeating units at a low optical thickness near one surface of the film, that remains substantially constant over a plurality of optical repeating units at a high optical thickness near the other surface or the film, and that monotonically increases from the low optical thickness to the high optical thickness through the remaining central portion of the film to define a reflection band.

6. The reflective film of claim 5, wherein the film is polymeric.