Non-imaging optical corner turner

• US 20050084212A1
• Filed: 10/20/2004
• Published: 04/21/2005
• Est. Priority Date: 12/10/1997
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Incorporated (Medtronic Plc)
• Inventors: Fein, Michael
• Granted Patent: US 7,127,141 B2
• Time in Patent Office: Days
• US Class Current: 385/39
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G02B 19/0019 having reflective surfaces only (e.g. louvre systems, systems with multiple planar reflectors)
• CPC Class Codes: G02B 19/0023 at least one surface having optical power
• CPC Class Codes: G02B 19/0033 characterised by the use
• CPC Class Codes: G02B 6/102 for infrared and ultraviolet radiation
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262

Abstract

The present invention provides a device and method to efficiently turn light from an optical fiber around a corner while avoiding the frustrated-TIR loss that would occur if the fiber were bent. The invention uses non-imaging optics which efficiently deal with beam divergence half-angles less than 90°. By recognizing that most light from a fiber optic source will have a divergence half-angle of less than 90 degrees, a practical solution is achieved using non-imaging optics.

Claims

1-31. -31. (canceled)

32. A method for designing a 3D non-imaging corner turner, said corner turner having an input port and an output port, and having an intended range of angles of output light rays, comprising:

selecting an initial geometry for said 3D non-imaging corner turner such that every section of said corner turner in a plane parallel to the plane of the bend is approximately equivalent to an in-plane section of a 2D non-imaging corner turner; and

optimizing said corner turner, further comprising;

computing a merit function for said corner turner, said merit function comprising a measure of the fraction of optical power entering said input port which is delivered to said output port within said intended range of output ray angles;

adjusting the corner turner geometry based upon results of said computing; and

successively performing said computing and said adjusting until an optimal non-imaging corner turner geometry is reached.

33. The method of claim 32 wherein said measure is a fraction of light rays entering said input port which are delivered to aid output port within said intended range of output ray angles.

34. An apparatus for efficiently deflecting light from an optical fiber around a corner, comprising:

an afferent light guide having a core;

a corner turning optical structure;

an interface defined between said afferent light guide and said corner turning optical structure, forming a corner turner side and an afferent light guide side, and

a defined special angle of incidence measured from a normal to said interface, said interface having a special property of reflecting with high probability any light rays which strike it from a corner turner side, if such rays exceed said defined special angle.

35. The apparatus of claim 34 wherein said core of said afferent light guide has a first refractive index, n₁, and said corner turning optical structure is comprised of a body of material having a second refractive index, n₂, wherein n₂ is greater than n₁.

36. The apparatus of claim 34 wherein said special property is caused by Total Internal Reflection (TIR).

37. The apparatus of claim 34 wherein a single-layer or multi-layer dielectric coating is applied at said interface, whereupon an optical interaction between said coating and said afferent light guide and said corner turning optical structure causes said special property.

38. The apparatus of claim 34, further comprising an efferent light guide, and

a second interface defined between said efferent light guide an said corner turning optical structure to form a corner turner side and an efferent light guide side,

said second interface having a second defined special angle of incidence measured from a normal to said second interface,

said second interface having a second special property of reflecting with high probability any light rays which strike it from the corner turner side, if such rays exceed said second defined special angle.

39. The apparatus of claim 38, wherein said second special property is caused by Total Internal Reflection (TIR).

40. The apparatus of claim 38, wherein a single-layer or multi-layer dielectric coating is applied t said second interface, whereupon an optical interaction between said coating and said efferent light guide and said corner turning optical structure causes said second special property.

41. The apparatus of claim 38, wherein said efferent light guide has a core having a refractive index n₃ and said corner turning structure has a refractive index of n₂, wherein n₂ is greater than n₃.

42. An apparatus for deflecting light from around a corner while conserving é

tendue, comprising;

an afferent optical light guide for delivering an afferent beam of light at a maximum divergence half-angle less than 90 degrees,

a non-imaging optical corner-turning structure having an exit port adjoining said afferent optical light guide to form an interface,

said corner-turning structure and said interface being adapted to prevent light entering said corner-turning structure from returning to said afferent optical light guide.

43. The apparatus of claim 42 wherein said corner-turning structure further comprises a plurality of reflective optical surfaces which direct light to pass through said exit port operative to prevent light return.

44. The apparatus of claim 42 wherein said corner-turning structure and said interface achieve said prevention of light return by utilizing angle-dependent reflection properties of said interface.

45. The apparatus of claim 44 wherein said interface transmits most rays of said afferent beam, but reflects most rays incident from said corner turning structure.

46. The apparatus of claim 45 wherein said angle-dependent reflection properties of said interface are achieved by Total Internal Reflection (TIR).

47. The apparatus of claim 45 wherein said angle-dependent reflection properties of said interface are achieved by a thin-film dielectric coating, said coating having an angle-dependent reflective behavior.

48-54. -54. (canceled)