Method and system for beam expansion in a display device

• US 20060126181A1
• Filed: 12/13/2004
• Published: 06/15/2006
• Est. Priority Date: 12/13/2004
• Status: Abandoned Application

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Levola, Tapani
• Application Number:
  US11/011,481
• Publication Number:
  US 20060126181A1
• Time in Patent Office: Days
• US Class Current: 359/567
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/4205 having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant

Abstract

An exit pupil extender with one input optical element and two exit optical elements disposed on different sides of the input optical element. The exit pupil extender also comprises two intermediate optical couplers, each disposed between the input optical element and one exit optical element. The couplers serve as exit pupil extending components. All optical elements and couplers are diffractive optical elements having grating lines. The grating lines of one optical element are substantially parallel to that of other optical elements, but the grating lines of the couplers are at substantially a 60-degree angle from that of the optical elements in order to optimize the exit pupil extending efficiency.

Claims

1. An optical device comprising:

a substrate of optical material having a first side and an opposing second side;

a first diffractive element disposed on the substrate for receiving a light beam;

a second diffractive element disposed on the substrate in relationship with the first diffractive element; and

an intermediate diffractive element disposed between the first and the second diffractive elements, wherein

at least part of the received light beam is diffracted in the first diffractive element for providing a diffracted light component to the intermediate diffractive element in an incident direction substantially within the first and second surface, and

at least part of the diffracted light component in the intermediate different element is coupled to the second diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted light component to exit the substrate by diffraction in the second diffractive element, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction for producing conical diffraction.

2. The optical device of claim 1, wherein angle in the conical diffraction is between 50 and 70 degrees.

3. The optical device of claim 1, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction so that the incident direction of the diffracted light component provided to the intermediate different element is within an angular range between 20 and 40 degrees relative to the pattern direction.

4. The optical device of claim 3, further comprising:

a third diffractive element disposed on the substrate in relationship with the first diffractive element spaced from the second diffractive element; and

a further intermediate diffractive element disposed between the first and the second diffractive elements, wherein

at least part of the received light beam is diffracted in the first diffractive element for providing a diffracted light component to the further intermediate diffractive element in an incident direction within the first and second surface, and

at least part of the diffracted light component in the further intermediate different element is coupled to the third diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted light component to exit the substrate by diffraction in the third diffractive element, wherein the further intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction such that the incident direction of the diffracted light component provided to the further intermediate different element is within an angular range between 50 and 70 degrees relative to the pattern direction.

5. The optical device of claim 1, wherein the received light beam is received in the first diffractive element through the first surface and at least part of the coupled diffracted light component exits the substrate through the second surface.

6. The optical device of claim 1, wherein the received light beam is received in the first diffractive element through the first surface and at least part of the coupled diffracted light component exits the substrate through the first surface.

7. The optical device of claim 1, wherein the intermediate diffractive element comprises a plurality of grooves forming the period pattern.

8. The optical device of claim 1, wherein the first diffractive element has a period pattern composed of a plurality of linear elements along a pattern direction substantially perpendicular to the incident direction.

9. The optical device of claim 1, wherein the second diffractive element has a period pattern composed of a plurality of linear elements along a pattern direction substantially perpendicular to the incident direction.

10. A method of optical coupling in an optical device, the optical device comprising:

a substrate of optical material having a first side and an opposing second side;

a first diffractive element disposed on the substrate for receiving a light beam, wherein at least part of the received light beam is diffracted in the first diffractive element for providing a diffracted light component; and

a second diffractive element disposed on the substrate in relationship to the first diffractive element so as to allow at least part of the diffracted light component to exit the substrate substantially by diffraction in the second diffractive element, said method comprising;

disposing an intermediate diffractive element between the first and the second diffractive elements, so as to allow part of the diffracted light component to enter the intermediate diffractive element between the first and second surfaces at an incident direction, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction to produce conical diffraction.

11. The method of claim 10, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction such that the incident direction of the diffracted light component is within an angular range between 20 and 40 degrees relative to the pattern direction.

12. The method of claim 11, wherein the optical device further comprises a third diffractive element disposed on the substrate in relationship to the first diffractive element spaced from the second device so as to allow at least part of the diffracted light component also to exit the substrate substantially by diffraction in the third diffractive element, said method further comprising:

disposing a further intermediate diffractive element between the first and the third diffractive elements, so as to allow part of the diffracted light component to enter the further intermediate diffractive element between the first and second surfaces at an incident direction, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction such that the incident direction of the diffracted light component is within an angular range between 50 and 70 degrees relative to the pattern direction.

13. The method of claim 10, wherein the first diffractive element having a substantially period pattern composed of substantially linear elements along a first pattern direction, and the second diffractive element having a substantially period pattern composed of substantially linear elements along a second pattern direction substantially parallel to the first pattern direction.

14. An electronic device comprising:

a data processing unit;

an optical engine operatively connected to the data processing unit for receiving image data from the data processing unit;

a display device operatively connected to the optical engine for forming an image based on the image data; and

an exit pupil extender, comprising;

a substrate of optical material having a first side and an opposing second side;

a first diffractive element disposed on the substrate for receiving a light beam;

a second diffractive element disposed on the substrate in relationship with the first diffractive element; and

an intermediate diffractive element disposed between the first and the second diffractive elements, wherein

at least part of the received light beam is diffracted in the first diffractive element for providing a diffracted light component to the intermediate diffractive element in an incident direction substantially within the first and second surface, and

at least part of the diffracted light component in the intermediate different element is coupled to the second diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted light component to exit the substrate by diffraction in the second diffractive element, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction for producing conical diffraction.

15. The electronic device of claim 14, wherein angle in the conical diffraction is between 50 and 70 degrees.

16. The electronic device of claim 14, wherein the intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction so that the incident direction of the diffracted light component provided to the intermediate different element is within an angular range between 20 and 40 degrees relative to the pattern direction.

17. The electronic device of claim 16, wherein the optical device further comprises:

a third diffractive element disposed on the substrate in relationship with the first diffractive element spaced from the second diffractive element; and

a further intermediate diffractive element disposed between the first and the second diffractive elements, wherein

at least part of the received light beam is diffracted in the first diffractive element for providing a diffracted light component to the further intermediate diffractive element in an incident direction within the first and second surface, and

at least part of the diffracted light component in the further intermediate different element is coupled to the third diffractive element substantially between the first and second surfaces so as to allow at least part of the coupled diffracted light component to exit the substrate by diffraction in the third diffractive element, wherein the further intermediate diffractive element has a substantially periodic pattern composed of substantially linear elements along a pattern direction such that the incident direction of the diffracted light component provided to the further intermediate different element is within an angular range between 50 and 70 degrees relative to the pattern direction.

18. The electronic device of claim 14, comprising a computer game device.

19. The electronic device of claim 14, comprising a digital camera.

20. The electronic device of claim 14, further comprising a communications unit for receiving signals containing information indicative of the image data, wherein the data processing unit is operatively connected to the communications unit for receiving the information.

21. The electronic device of claim 20, comprising a mobile terminal.