Optic with extruded conic profile

• US 8,767,294 B2
• Filed: 07/05/2011
• Issued: 07/01/2014
• Est. Priority Date: 07/05/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Chen, Liying, Large, Timothy, Emerton, Neil, Travis, Adrian
• Primary Examiner(s): FONT, FRANK G
• Application Number:
  US13/176,583
• Publication Number:
  US 20130010355A1
• Time in Patent Office: 1,092 Days
• Field of Search: 359/451, 359/537, 359/592, 359/595, 359/597, 359/598, 359/402, 348/335, 348/336, 385/43, 385/39, 385/129, 385/130
• US Class Current: 359/402
• CPC Class Codes: B29D 11/00663 Production of light guides
• CPC Class Codes: G02B 23/08 Periscopes arrangements on floating structures of underwater viewing devices B63C11/49; arrangement of visual watch equipment on submarines B63G8/38
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen

Abstract

A transmission optic having a transparent sheet with opposing front and back faces and an end face adjacent the front and back faces. The separation between the back face and a nearest point on the front face varies as a conic function of distance along the front face from that point to the end face.

Claims

1. A transmission optic comprising:

a transparent sheet with opposing front and back faces and an end face adjacent the front and back faces, a separation between the back face and a nearest point on the front face varying as a conic function of distance along the front face from that point to the end face, the conic function equal to a constant plus a term linear in the distance plus a square root of a quadratic polynomial of the distance,

a shape of the transparent sheet being such that an incidence angle of light propagating through the sheet initially increases, relative to a surface normal of the sheet, and then decreases with each successive bounce.

2. The transmission optic of claim 1 wherein the front face is planar.

3. The transmission optic of claim 2 wherein a profile of the back face is an extrusion of the conic function in a direction parallel to a length of the end face.

4. The transmission optic of claim 1 wherein light refracted through the end face within a range of incidence angles escapes from the front face over a corresponding, continuous range of distances from the end face, and wherein the range of distances spans at least half the length of the sheet.

5. The transmission optic of claim 4 wherein each light ray refracted within the range of incidence angles undergoes an equal number of reflections within the sheet.

6. The transmission optic of claim 1 wherein the sheet is monolithic.

7. The transmission optic of claim 1 wherein the sheet comprises acrylic or polycarbonate or glass.

8. The transmission optic of claim 1 wherein the sheet is injection-molded.

9. The transmission optic of claim 1 wherein an aspect ratio of a length-to-greatest-thickness of the sheet is one-hundred or more.

10. The transmission optic of claim 1 further comprising one or more of an optical diffuser and a turning film supported on the front face of the sheet.

11. The transmission optic of claim 1 further comprising a phosphor supported on the front face of the sheet.

12. The transmission optic of claim 1 further comprising a cladding supported on the back face of the sheet, the cladding having a lower refractive index than the sheet.

13. The transmission optic of claim 1 wherein the end face is a first of two opposing end faces each adjacent the front and back faces, and wherein the separation is greatest between the first and second end faces and tapers down on approaching both the first end face and the second end face.

14. The transmission optic of claim 1 wherein the end face is a first of two opposing end faces each adjacent the front and back faces, and wherein a separation between the back face and a nearest point on the front face varies as a conic function of a complementary distance along the front face from that point to the second end face, the conic function equal to a constant plus a term linear in the complementary distance plus a square root of a quadratic polynomial of the complementary distance.

15. A transmission optic comprising:

a transparent sheet with opposing front and back faces and opposing first and second end faces each adjacent the front and back faces, a separation between the back face and a nearest point on the front face varying as a conic function of distance along the front face from that point to the first end face, the separation being greatest between the first and second end faces and tapering down on approaching both the first end face and the second end face, the conic function equal to a constant plus a term linear in the distance plus a square root of a quadratic polynomial of the distance.

16. The transmission optic of claim 15 further comprising one or more of an optical diffuser, a turning film, and a phosphor overcoat supported on the front face of the transmission optic.

17. The transmission optic of claim 15 further comprising a camera configured to receive an image from the first end face of the transmission optic, the image refracting through the first end face within a range of incidence angles and entering the front face over a corresponding, continuous range of distances from the first end face, the range of distances spanning at least half the length of the sheet.

18. A method for making a transmission optic comprising a transparent sheet with opposing front and back faces and opposing first and second end faces each adjacent the front and back faces, the method comprising:

computing a desired separation between the back face and a nearest point on the front face as a conic function of distance along the front face from that point to the first end face, the separation being greatest between the first and second end faces and tapering down on approaching both the first end face and the second end face, the conic function equal to a constant plus a term linear in the distance plus a square root of a quadratic polynomial of the distance;

machining at least one mold surface to define a void conforming to the conic function; and

filling the void with a transparent plastic material.

19. The method of claim 18 wherein filling the void includes injecting the transparent plastic material in liquid form upon the at least one mold surface.

20. The method of claim 18 further comprising:

cooling the at least one mold surface to harden the transparent plastic material; and

after cooling, releasing the sheet from the at least one mold surface.