Optical film

• US 7,297,393 B2
• Filed: 07/31/2006
• Issued: 11/20/2007
• Est. Priority Date: 12/21/1993
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Weber, Michael F., Ouderkirk, Andrew J., Stover, Carl A., Jonza, James M.
• Primary Examiner(s): Chen; Vivian
• Application Number:
  US11/461,406
• Publication Number:
  US 20060286396A1
• Time in Patent Office: 477 Days
• Field of Search: None
• US Class Current: 428/212
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/003 Reflective
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: B32B 2038/0028 Stretching, elongating
• CPC Class Codes: B32B 2323/00 Polyalkenes
• CPC Class Codes: B32B 2325/00 Polymers of vinyl-aromatic compounds, e.g. polystyrene
• CPC Class Codes: B32B 2333/08 Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2551/08 Mirrors
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/305 : including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 : Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133536 : Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 : Dielectric stack polarisers
• CPC Class Codes: G02F 1/13362 : providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: Y10S 428/91 : Product with molecular orientation
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/261 : In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/31507 : Of polycarbonate
• CPC Class Codes: Y10T 428/3154 : Of fluorinated addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31616 : Next to polyester [e.g., alkyd]
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31935 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31938 : Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Birefringent optical films have a Brewster angle (the angle at which reflectance of p-polarized light goes to zero) which is very large or is nonexistent. This allows for the construction of multilayer mirrors and polarizers whose reflectivity for p-polarized light decreases slowly with angle of incidence, are independent of angle of incidence, or increase with angle of incidence away from the normal. As a result, multilayer films having high reflectivity (for both planes of polarization for any incident direction in the case of mirrors, and for the selected direction in the case of polarizers) over a wide bandwidth can be achieved.

Claims

1. A multilayered optical film, comprising:

a plurality of alternating layers of a first and second material, the material layers having refractive indices nx, ny associated respectively with orthogonal in-plane x and y axes parallel to a surface of the film, the material layers also having refractive indices nz associated with a z-axis perpendicular to the film plane;

wherein adjoining layers of the first and second material form an interface, the first material layer being birefringent and having an index of refraction associated with at least one of the in-plane axes that is higher than the associated in-plane index of the second material layer; and

wherein the refractive index nz of the first material layer is selected to be less than the refractive index nz of the second material layer, such that reflectivity of the interface for p-polarized light monotonically increases with angle of incidence.

2. The multilayered optical film of claim 1, wherein the first and second materials are polymeric.

3. The multilayered optical film of claim 2, wherein the first and second materials have similar rheological properties such that they can be co-extruded.

4. The multilayered optical film of claim 2, wherein the first material is a crystalline naphthalene dicarboxylic acid polyester.

5. The multilayered optical film of claim 1, wherein the first material layer is uniaxially birefringent.

6. The multilayered optical film of claim 1, wherein the first material layer is biaxially birefringent.

7. The multilayered optical film of claim 1, wherein the multilayered optical film is a reflective polarizer.

8. The multilayered optical film of claim 1, wherein the multilayered optical film is a mirror.