Optical system

Patent metadata

Field	Value
Publication number	US-2023415437-A1
Application number	US-202318463372-A
Country	US
Kind code	A1
Filing date	Sep 8, 2023
Priority date	Sep 3, 2015
Publication date	Dec 28, 2023
Grant date	—

Abstract

An optical system includes a partial reflector having an average optical reflectance of at least 30% in a plurality of wavelengths, an image source disposed to emit image light toward the partial reflector, and a reflective polarizer disposed proximate the partial reflector. The reflective polarizer is curved about two orthogonal axes and can include at least one layer substantially optically uniaxial at at least one location. The image light may be transmitted by the reflective polarizer after it is first reflected by the reflective polarizer. Substantially any chief light ray having at least first and second wavelengths at least 150 nm apart in the plurality of wavelengths and emitted by the image source and transmitted by a stop surface or exit pupil of the optical system has a color separation distance of less than 1.5 percent of a field of view.

First claim

What is claimed is:

1 . An optical system, comprising:
an image source; an exit pupil; a first optical stack disposed between the image source and the exit pupil and comprising:
a first optical lens;
a partial reflector having an average optical reflectance of at least 30% in a pre-determined plurality of wavelengths; and
a second optical stack disposed between the first optical stack and the exit pupil and comprising:
a second optical lens;
a reflective polarizer convex about orthogonal first and second axes; and
a first quarter wave retarder disposed between the reflective polarizer and the first optical stack,
wherein substantially any chief light ray having at least first and second wavelengths at least 150 nm apart in the pre-determined plurality of wavelengths and emitted by the image source and transmitted by the exit pupil has a color separation distance at the exit pupil of less than 1.5 percent of a field of view at the exit pupil.

2 . The optical system of claim 1 , wherein the color separation distance at the exit pupil is less than 20 arc minutes.

3 . The optical system of claim 1 , wherein the reflective polarizer has at least one first location having a radial distance, r1, from an optical axis passing through an apex of the reflective polarizer and a displacement, s1, from a plane perpendicular to the optical axis at the apex, s1/r1 being at least 0.2, and wherein for an area of the reflective polarizer defined by s1 and r1, a maximum variation of a transmission axis of the reflective polarizer is less than 3 degrees.

4 . The optical system of claim 1 , wherein the reflective polarizer has at least one first location having a radial distance, r1, from an optical axis passing through an apex of the reflective polarizer and a displacement, s1, from a plane perpendicular to the optical axis at the apex, s1/r1 being at least 0.2, and wherein for an area of the reflective polarizer defined by s1 and r1, a maximum variation of a transmission axis of the reflective polarizer is less than 2 degrees.

5 . The optical system of claim 1 , wherein the reflective polarizer comprises at least one layer that is substantially optically biaxial at at least one first location on the at least one layer away from an optical axis passing through an apex of the reflective polarizer and substantially optically uniaxial at at least one second location on the at least one layer away from the optical axis.

6 . The optical system of claim 1 , wherein substantially any chief light ray that is emitted by the image source and that is transmitted through the exit pupil is incident on each of the reflective polarizer and the partial reflector with an angle of incidence less than 30 degrees.

7 . The optical system of claim 1 , wherein substantially any chief light ray that is emitted by the image source and that is transmitted through the exit pupil is incident on each of the reflective polarizer and the partial reflector with an angle of incidence less than 25 degrees.

8 . The optical system of claim 1 , wherein the color separation distance at the exit pupil is less than 1.2 percent of the field of view at the exit pupil.

9 . An optical system, comprising:
a partial reflector having an average optical reflectance of at least 30% in a desired plurality of wavelengths; an image source disposed to emit image light toward the partial reflector; and a multilayer reflective polarizer disposed proximate the partial reflector, the multilayer reflective polarizer being curved about two orthogonal axes and comprising at least one layer substantially optically uniaxial at at least one location, the partial reflector and the multilayer reflective polarizer being disposed between the image source and a stop surface of the optical system, wherein the image light is transmitted by the multilayer reflective polarizer after it is first reflected by the multilayer reflective polarizer, and wherein substantially any chief light ray having at least first and second wavelengths at least 150 nm apart in the desired plurality of wavelengths and emitted by the image source and transmitted by the stop surface has a color separation distance at the stop surface of less than 1.5 percent of a field of view at the stop surface.

10 . The optical system of claim 9 , wherein the at least one layer at the at least one location has a first refractive index in a thickness direction, a second refractive index in a second direction orthogonal to the thickness direction, and a third refractive index in a third direction orthogonal to the thickness direction and to the second direction, an absolute value of a difference in the first and second refractive indices being less than 0.02, an absolute value of a difference in the second and third refractive indices being greater than 0.05.

11 . The optical system of claim 9 , wherein the at least one layer at the at least one location has a first refractive index in a thickness direction, a second refractive index in a second direction orthogonal to the thickness direction, and a third refractive index in a third direction orthogonal to the thickness direction and to the second direction, an absolute value of a difference in the first and second refractive indices being less than 0.01, an absolute value of a difference in the second and third refractive indices being greater than 0.1.

12 . The optical system of claim 9 , wherein substantially any chief light ray that is emitted by the image source and that is transmitted through the stop surface is first incident on each of the multilayer reflective polarizer and the partial reflector with an angle of incidence less than 30 degrees.

13 . The optical system of claim 9 , wherein substantially any chief light ray that is emitted by the image source and that is transmitted through the stop surface is first incident on each of the multilayer reflective polarizer and the partial reflector with an angle of incidence less than 25 degrees.

14 . The optical system of claim 9 , wherein the color separation distance at the stop surface is less than 1.2 percent of the field of view at the stop surface.

Assignees

• 3M Innovative Properties Company

Inventors

• Ouderkirk Andrew J
• Wong Timothy L
• Yun Zhisheng
• Mcdowell Erin A
• Ambur Gregg A

Classifications

• B29D11/00644 Primary

  polarizing · CPC title

• G02B13/0055

  employing a special optical element · CPC title

• G02B17/0856

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

• G02B5/30

  Polarising elements (light-modulating devices with active elements G02F1/00) · CPC title

• G02B5/305

  including organic materials, e.g. polymeric layers · CPC title