Method of fabricating an optical assembly

Patent metadata

Field	Value
Publication number	US-11630291-B2
Application number	US-202217583598-A
Country	US
Kind code	B2
Filing date	Jan 25, 2022
Priority date	May 16, 2017
Publication date	Apr 18, 2023
Grant date	Apr 18, 2023

Abstract

A method of fabricating an optical assembly includes providing a first mold having a first curved mold surface; placing a substantially flat reflective polarizer; on the first curved mold surface and applying at least one of pressure and heat to at least partially conform the reflective polarizer to the first curved mold surface; providing a second mold comprising a second mold surface, the first and second mold surfaces defining a mold cavity therebetween; substantially filling the mold cavity with a flowable material having a temperature greater than a glass transition temperature of the reflective polarizer; and solidifying the flowable material to form a solid optical element bonded to the reflective polarizer. A maximum variation of an orientation of a pass polarization state across the bonded reflective polarizer is within about 3 degrees of a maximum variation of the orientation of the pass polarization state across the substantially flat reflective polarizer.

First claim

What is claimed is:

1. A method of fabricating an optical assembly, comprising:
providing a first mold comprising a first curved mold surface having a best-fit spherical first radius of curvature in a range from about 30 mm to about 1000 mm;
providing a substantially flat reflective polarizer, each location on the reflective polarizer having a maximum reflectance greater than about 70% for a block polarization state and a maximum transmittance greater than about 70% for an orthogonal pass polarization state, a maximum variation of an orientation of the pass polarization state across the reflective polarizer being about θ1 degrees;
placing the substantially flat reflective polarizer on the first curved mold surface and applying at least one of pressure and heat to at least partially conform the substantially flat reflective polarizer to the first curved mold surface;
providing a second mold comprising a second mold surface spaced apart from and aligned with the first mold surface, the first and second mold surfaces defining a mold cavity therebetween;
substantially filling the mold cavity with a flowable material having a temperature greater than a glass transition temperature of the reflective polarizer; and
solidifying the flowable material to form a solid optical element bonded to the reflective polarizer, a maximum variation of an orientation of the pass polarization state across the bonded reflective polarizer being about θ2 degrees, θ1 and θ2 being within about 3 degrees of each other.

2. The method of claim 1 , wherein the mold cavity is substantially filled with the flowable material through a gate connected to the mold cavity.

3. The method of claim 1 , wherein the solid optical element is permanently bonded to the reflective polarizer.

4. The method of claim 1 , wherein a ratio of a sag to the best-fit spherical first radius of curvature of the first curved mold surface is in a range from about 0.02 to about 0.2.

5. The method of claim 1 , wherein the substantially flat reflective polarizer is stretched along a first axis, and the flowable material flows into the mold cavity along a second direction substantially perpendicular to the first axis.

6. The method of claim 1 , wherein the substantially flat reflective polarizer is stretched along a first axis, and the flowable material flows into the mold cavity along the first axis.

7. The method of claim 1 , wherein the substantially flat reflective polarizer comprises a plurality of interference layers, each interference layer reflecting or transmitting light primarily by optical interference.

8. The method of claim 1 , wherein θ1 and θ2 are within about 1 degree of each other.

9. The method of claim 1 , wherein the first curved mold surface has a first average surface roughness, wherein the placing step comprises placing the substantially flat reflective polarizer on the first curved mold surface with a first major surface of the reflective polarizer facing the first curved mold surface, and wherein after the solidifying step, the first major surface of the bonded reflective polarizer has a second average surface roughness greater than the first average surface roughness.

10. The method of claim 1 , wherein the substantially flat reflective polarizer has a first maximum thickness variation across the reflective polarizer, and the bonded reflective polarizer has a second maximum thickness variation across the reflective polarizer, the first and second maximum thickness variations being within 5% of each other.

11. A method comprising:
fabricating an optical assembly according to the method of claim 1 ; and
disposing a first optical lens proximate the optical assembly such that the reflective polarizer faces the first optical lens, a curved first major surface of the first optical lens having a best-fit spherical first radius of curvature in a range from about 20 mm to about 200 mm, and an opposing second major surface of the first optical lens having a best-fit spherical second radius of curvature greater than about 500 mm, wherein a partial reflector is disposed on and conforms to the first curved major surface of the first optical lens and has an average optical reflectance of at least 30% in a predetermined wavelength range, and wherein a first retarder layer is disposed on and conforms to the second major surface of the first optical lens.

12. A method of fabricating an optical assembly, comprising:
providing a first mold comprising a first curved mold surface having a best-fit spherical first radius of curvature in a range from about 30 mm to about 1000 mm;
providing a substantially flat reflective polarizer having an average optical transmittance greater than about 70% for a first polarization state and an average optical reflectance greater than about 70% for an orthogonal second polarization state;
placing the substantially flat reflective polarizer on the first curved mold surface with a first major surface of the reflective polarizer facing the first curved mold surface and having a first average surface roughness;
applying at least one of pressure and heat to at least partially conform the substantially flat reflective polarizer to the first curved mold surface;
providing a second mold comprising a second mold surface spaced apart from and aligned with the first mold surface, the first and second mold surfaces defining a mold cavity therebetween;
substantially filling the mold cavity with a flowable material having a temperature greater than a glass transition temperature of the reflective polarizer; and
solidifying the flowable material to form a solid optical element bonded to the reflective polarizer, the first major surface of the bonded reflective polarizer having a second average surface roughness greater than the first average surface roughness.

13. The method of claim 12 , wherein the first average surface roughness is about 0.05 micrometers and the second average surface roughness is about 0.1 micrometers.

14. The method of claim 12 , wherein the substantially flat reflective polarizer has a first maximum thickness variation across the reflective polarizer, and the bonded reflective polarizer has a second maximum thickness variation across the reflective polarizer, the first and second maximum thickness variations being within 5% of each other.

15. The method of claim 12 , wherein the substantially flat reflective polarizer has a maximum variation of an orientation of a pass polarization state across the reflective polarizer of about θ1 degrees, and wherein a maximum variation of an orientation of the pass polarization state across the bonded reflective polarizer is about θ2 degrees, θ1 and θ2 being within about 3 degrees of each other.

16. A method of fabricating an optical assembly, comprising:
providing a first mold comprising a first curved mold surface having a best-fit spherical first radius of curvature in a range from about 30 mm to about 1000 mm;
providing a substantially flat reflective polarizer having an average reflectance greater than about 70% for a first polarization state in a predetermined wavelength range and an average transmittance greater than about 70% for an orthogonal second polarization state in the predetermined wavelength range, the substantially flat reflective polarizer having a first maximum thickness variation across the reflective polarizer;
placing the substantially flat reflective polarizer on the first curved mold surface and applying at least one of pressure and heat to at least partially conform the substantially flat reflective polarizer to the first curved mold surface;
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Assignees

• 3M Innovative Properties Company

Inventors

• Etter Jo A
• Wong Timothy L
• Yun Zhisheng
• Ambur Gregg A
• Sonnek Benjamin G
• Jennings Robert M

Classifications

• G02B3/00

  Simple or compound lenses · CPC title

• G02B17/0804

  using two curved mirrors (G02B17/0864, G02B17/0896 takes precedence) · CPC title

• G02B17/0856 Primary

  comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors · CPC title

• G02B27/28

  for polarising (used in stereoscopes G02B30/25) · CPC title

• G02B5/3025

  Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence) · CPC title