Light-guide device with optical cutoff edge and corresponding production methods

• US 10,437,031 B2
• Filed: 06/03/2018
• Issued: 10/08/2019
• Est. Priority Date: 11/08/2016
• Status: Active Grant

• Current Assignee: Lumus Ltd.
• Original Assignee: Lumus Ltd.
• Inventors: Danziger, Yochay, Friedmann, Edgar
• Primary Examiner(s): Beatty, Collin X
• Application Number:
  US15/996,476
• Publication Number:
  US 20180275384A1
• Time in Patent Office: 492 Days
• Field of Search: 359834
• CPC Class Codes: B29D 11/00663 Production of light guides
• CPC Class Codes: B29D 11/00875 on light guides
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 17/00 Systems with reflecting surfaces, with or without refracting elements
• CPC Class Codes: G02B 17/086 wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence

Abstract

A light-guide device includes a light guiding element (13) with a number of faces, including two parallel faces (26), for guiding light by internal reflection. A transparent optical element (19) has an interface surface for attachment to a coupling surface (14) of the light guiding element, and is configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface (14) so as to propagate within the light guiding element (13). A non-transparent coating (15) is applied to at least part of one or more faces of the light guiding element (13), defining an edge (17) adjacent to, or overlapping, the coupling surface (14) of the light guiding element (13). A quantity of transparent adhesive is deployed between the coupling surface and the interface surface so as to form an optically transmissive interface. An overspill region 31 of the adhesive extends to, and overlaps, the edge (17).

Claims

1. An apparatus comprising:

(a) a light guiding element having a plurality of faces including a pair of parallel faces, said light guiding element being configured for guiding light by internal reflection at said parallel faces, one of said plurality of faces providing a coupling surface;

(b) a transparent optical element having an interface surface for attachment to said coupling surface, said transparent optical element being configured such that light propagating within said transparent optical element passes through said interface surface and said coupling surface so as to propagate within the light guiding element;

(c) a non-transparent coating applied to at least part of at least one of said parallel faces of said light guiding element, said coating defining an edge adjacent to, or overlapping, said coupling surface of said light guiding element; and

(d) a quantity of transparent adhesive deployed between said coupling surface and said interface surface so as to form an optically transmissive interface, said adhesive extending to, and overlapping, said edge,

wherein said edge defines an optical cutoff edge for light rays passing from said transparent optical element into said light guiding element, and wherein said non-transparent coating is configured to generate internal reflection at an underlying region of said at least one of said parallel faces.

2. The apparatus of claim 1, wherein said coupling surface is provided on one of said parallel faces.

3. The apparatus of claim 2, wherein said coating extends between said coupling surface and said interface surface.

4. The apparatus of claim 1, wherein said coupling surface is inclined relative to said parallel faces.

5. The apparatus of claim 4, wherein said coupling surface and said parallel face meet at a ground edge, and wherein said edge is non-overlapping with said ground edge.

6. The apparatus of claim 5, wherein said adhesive fills a recess formed between said ground edge and said interface surface.

7. The apparatus of claim 4, wherein said coupling surface is obliquely inclined relative to said parallel faces.

8. The apparatus of claim 4, wherein said coupling surface is perpendicular to said parallel faces.

9. The apparatus of claim 1, wherein said interface surface is larger than said coupling surface.

10. The apparatus of claim 1, wherein said coating is a metal coating.

11. The apparatus of claim 1, wherein said coating is a dielectric coating.

12. The apparatus of claim 1, wherein said transparent optical element is a coupling prism configured to provide an input surface oriented for input of light into said light guiding element.

13. An apparatus comprising:

(a) a light guiding element having a plurality of faces including a pair of parallel faces, said light guiding element being configured for guiding light by internal reflection at said parallel faces, one of said plurality of faces providing a coupling surface;

(b) a coupling prism having an interface surface adhered to said coupling surface and an input surface for input of light into the light guiding element; and

(c) a non-transparent coating applied to at least part of said coupling surface of said light guiding element and extending between said light guiding element and said coupling prism, said coating defining an optical cutoff edge for light passing from said coupling prism through said coupling surface into said light guiding element, and wherein said non-transparent coating is configured to generate internal reflection at an underlying region of said at least one parallel face.

14. The apparatus of claim 13, wherein said coupling prism is adhered to said coupling surface of said light guiding element without adhesive.

15. An apparatus comprising:

(a) a light guiding element having a plurality of faces including first and second parallel faces, said light guiding element being configured for guiding light by internal reflection at said first and second parallel faces, one of said plurality of faces providing a coupling surface;

(b) a coupling prism having an interface surface for attachment to said coupling surface and an input surface for input of light into the light guiding element; and

(c) a quantity of transparent adhesive deployed between said coupling surface and said interface surface so as to form an optically transmissive interface, a part of said quantity of adhesive forming a partial filling of an angled recess between said light guiding element and said coupling prism,

wherein an air gap extends along one of said faces of said light guiding element beneath said partial filling, said air gap terminating at an edge within said adhesive so as to define an optical cutoff edge adjacent to said coupling surface of said light guiding element.

16. A method for producing an optical assembly, the method comprising:

(a) providing a light guiding element having a plurality of faces including first and second parallel faces, said light guiding element being configured for guiding light by internal reflection at said first and second parallel faces;

(b) applying a coating to at least part of at least one of said plurality of faces of said light guiding element;

(c) grinding said light guiding element along a plane intersecting said coating so as to simultaneously form a coupling surface of said light guiding element and an edge of said coating; and

(d) bonding to said coupling surface an interface surface of a transparent optical element, the transparent optical element being configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface so as to propagate within the light guiding element,

wherein said bonding is performed by applying a quantity of a transparent adhesive between said coupling surface and said interface surface, said quantity of adhesive being applied such that, when said coupling surface and said interface surface are pressed together, an excess of said transparent adhesive overlaps said edge of said coating.

17. The method of claim 16, wherein said coating is a non-transparent coating such that said edge defines an optical cutoff edge.

18. The method of claim 16, further comprising a step of selectively removing said coating so as to leave a cutoff edge defined by an edge of an air-gap formed in said transparent adhesive.

19. A method for producing an optical assembly, the method comprising:

(a) providing a light guiding element having a plurality of faces including a pair of parallel faces, said light guiding element being configured for guiding light by internal reflection at said parallel faces, one of said plurality of faces providing a coupling surface;

(b) applying a non-transparent coating to at least part of at least one of said parallel faces, said non-transparent coating defining an edge adjacent to, or overlapping, said coupling surface of said light guiding element; and

(c) bonding to said coupling surface an interface surface of a transparent optical element, the transparent optical element being configured such that light propagating within the transparent optical element passes through the interface surface and the coupling surface so as to propagate within the light guiding element,

wherein said bonding is performed by applying a quantity of a transparent adhesive between said coupling surface and said interface surface, said quantity of adhesive being applied such that, when said coupling surface and said interface surface are pressed together, an excess of said transparent adhesive overlaps said edge of said coating,

and wherein said edge defines an optical cutoff edge for light rays passing from said transparent optical element into said light guiding element, and wherein said non-transparent coating is configured to generate internal reflection at an underlying region of said at least one parallel face including where overlapped by the excess of said transparent adhesive.

20. The method of claim 19, wherein said coupling surface is provided on one of said parallel faces.