LIGHT TUNNEL AND METHOD OF MANUFACTURING THE SAME

1 - 28 . (canceled)

29 . A method of forming an optical device comprising:

forming a reflective coating on a first element to form a first reflective flat surface and on a second element to form a second reflective flat surface;

forming a reflective coating on a sidewall of each of two flat spacer plates to form a reflective sidewall on each flat spacer plate;

arranging the two flat spacer plates in a single plane between the first and second elements with the reflective sidewalls of the two flat spacer plates facing each other by a gap; and

securing the first and second elements to the two flat spacer plates with the first and second reflective flat surfaces facing each other and disposed on opposite sides of the single plane thereby forming a light tunnel passage defined by the first and second reflective flat surfaces and the two reflective sidewalls.

30 . The method of claim 29 , wherein the light tunnel passage has a rectangular cross-section.

31 . The method of claim 29 , wherein the first reflective flat surface directly contacts the two flat spacer plates, and wherein the second reflective flat surface directly contacts the two flat spacer plates.

32 . The method of claim 29 , wherein the first reflective flat surface is parallel with the single plane, and wherein the second reflective flat surface is parallel with the single plane.

33 . The method of claim 29 , wherein after securing, the facing reflective sidewalls are arranged at an angle with respect to each other such that the light tunnel passage is tapered.

34 . The method of claim 29 , wherein before forming the reflective coating on each of the two flat spacer plates, the method further comprises arranging the two flat spacer plates in a stack, wherein the reflective coating is formed on a sidewall of the stack in a single batch coating process.

35 . The method of claim 34 , further comprising forming the reflective coating on another sidewall of the stack during the single batch coating process.

36 . The method of claim 29 , wherein the light tunnel passage has a constant height that is defined by the space between the first reflective flat surface and the second reflective flat surface.

37 . The method of claim 36 , wherein the light tunnel passage has a constant width that is defined by the gap between the facing reflective sidewalls.

38 . The method of claim 36 , wherein the light tunnel passage has a non-constant width that is defined by the gap between the facing reflective sidewalls.

39 . The method of claim 38 , wherein the non-constant width varies non-linearly along the length of the light tunnel passage.

40 . A method of fabricating an optical device, the method comprising:

coating at least one surface of each of two elements with a surface reflective coating to define two reflective flat surfaces;

coating at least one sidewall of each of two flat spacer plates with a sidewall reflective coating to define spacer plates each having a reflective sidewall; and

securing the two reflective flat surfaces and the two flat spacer plates together with the two reflective flat surfaces facing each other and the two flat spacer plates disposed in a single plane between the two facing reflective flat surfaces and with the reflective sidewalls facing each other whereby a light tunnel passage is defined by the two facing reflective flat surfaces and the two facing reflective sidewalls,

wherein the two reflective flat surfaces are parallel with one another and parallel to the single plane, and wherein the light tunnel passage has a rectangular cross-section with a constant dimension in a direction transverse to the single plane.

41 . The method of claim 40 , wherein the securing includes securing the two flat spacer plates arranged in the single plane with the facing reflective sidewalls parallel with each other with a constant gap W between the two facing reflective sidewalls, whereby the light tunnel passage has a constant dimension W.

42 . The method of claim 40 , wherein the securing includes securing the two flat spacer plates arranged in the single plane with the facing reflective sidewalls arranged at an angle to each other, whereby the light tunnel passage is tapered along the length of the light tunnel passage.

43 . The method of claim 40 , wherein the surface reflective coating has a reflectivity of at least 0.9 for a design wavelength or wavelength band, and wherein the sidewall reflective coating has a reflectivity of at least 0.9 for the design wavelength or wavelength band.

44 . The method of claim 40 , wherein the surface reflective coating has a reflectivity of at least 0.95 for a design wavelength or wavelength band, and wherein the sidewall reflective coating has a reflectivity of at least 0.95 for the design wavelength or wavelength band.

45 . A method of forming an optical device comprising:

forming a first reflective coating on a first element;

forming a second reflective coating on a second element;

arranging the first element and the second element such that the first reflective coating faces and is parallel to the second reflective coating;

forming a first sidewall reflective coating on a third element;

forming a second sidewall reflective coating on a fourth element;

arranging the third element and the fourth element in a single plane and with the first sidewall reflective coating facing the second sidewall reflective coating;

arranging the third element and the fourth element between the first element and the second element;

securing the first element to the third and fourth elements; and

securing the second element to the third and fourth elements to form a light tunnel passage that is defined by a space between the first reflective coating, the second reflective coating, the first sidewall reflective coating, and the second sidewall reflective coating, wherein the light tunnel passage has a rectangular cross-section with a height equal to the constant thickness of the third and fourth elements.

46 . The method of claim 45 , wherein the height of the light tunnel passage is constant throughout the light tunnel passage, and wherein a width of the light tunnel passage varies throughout the light tunnel passage, the width being measured between the first sidewall reflective coating and the second sidewall reflective coating.

47 . The method of claim 45 , wherein the method further comprises arranging the third element over the fourth element before forming the first and second sidewall reflective coatings.

48 . The method of claim 47 , wherein the first and second sidewall reflective coatings are formed on outer sidewalls of the third element and the fourth element using a single batch coating process.