Optical tunnel and method for manufacturing the same

Abstract

The present invention provides an optical tunnel and a method for manufacturing the same. [Solution] The optical device comprises two flat plates, each having a reflective plane, and two flat spacer plates of thickness H, each having a reflective sidewall. The flat plates and flat spacer plates are stacked and arranged so that their reflective planes face each other, and the flat spacer plates are placed between the two flat plates in a single plane, with their reflective sidewalls facing each other and a gap between the two reflective sidewalls. The opposing reflective planes and opposing reflective sidewalls define an optical tunnel passage of dimension H in the transverse direction relative to the single plane. The opposing reflective sidewalls can be parallel to each other, spaced apart by a certain gap W, to provide an optical tunnel passage with a certain cross-sectional area H × W, or they can be angled to provide a tapered optical tunnel passage.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims priority to U.S. Provisional Patent Application No. 62 / 665,152, filed on May 1, 2018, the entire content of which is incorporated herein by reference.

Background Art

[0002] The following relates to optical device technology, photonics technology, optical tunnel device technology, and their applications, such as optical mixing, optical projector systems, projection TVs, etc.

[0003] An optical tunnel comprises a tube having a reflective inner surface. In an optical design where the optical tunnel connects a light source to a downstream optical component, the optical tunnel functions as an optical integrator rod for homogenizing light. For example, in a projection display device, a projector lamp may be focused on the input aperture of the optical tunnel, whereby the light exiting the output aperture of the optical tunnel is made more uniform over the area of the output aperture. The optical tunnel is mainly etendue - preserving, and thus the divergence characteristics of the light output at the exit aperture can be designed by an appropriate taper within the optical tunnel. The optical tunnel can provide additional or other advantages, such as providing a sealed optical path for connecting a high - temperature incandescent lamp to a heat - sensitive downstream optical system. Light can also be shaped using an optical tunnel. For example, in a projector system for a pixelated display device, an optical tunnel having a rectangular cross - section can be designed to have a rectangular light source at the output aperture and be adapted to a rectangular digital micromirror device (DMD), a pixelated LCD display device, etc.

[0004] An optical tunnel provides an optical integrator (light mixing) effect, relying on a strong interaction between light and the reflective inner surfaces of the optical tunnel. In geometric ray modeling, this corresponds to the multiple reflections (on average) of light rays passing through the optical tunnel. Therefore, for high optical efficiency, the inner surface of the optical tunnel should have a very high reflectivity. If there are N reflections (on average) and the surface has reflectivity r, then the output is r N Therefore, the loss is (1-r N ) For example, if there is an average of N=4 reflections at r=95%, the optical loss is (1-0.95 4 The loss is 18%. When the reflectance is increased to r=97%, this decreases to an 11% loss, and at r=98%, the loss decreases to 7.8%. In one method for manufacturing a rectangular cross-section optical tunnel with high optical efficiency, four glass plates with a high reflectance coating are arranged end to end, with each plate oriented at 90° to the adjacent plate, and the high reflectance coating forming the inner surface of the optical tunnel. A mandrel can be used to temporarily hold the four glass plates, and their adjacent ends can be bonded or otherwise fixed.

[0005] Here, we will disclose some improvements. [Overview of the project] [Means for solving the problem]

[0006] In some exemplary embodiments disclosed herein, an optical device is disclosed comprising a first element having a first reflective plane, a second element having a second reflective plane, and two flat spacer plates, each having a reflective sidewall. The two flat spacer plates are arranged on a single plane such that their reflective sidewalls face each other and there is a gap between the two opposing reflective sidewalls. The first reflective plane is arranged parallel to the single plane containing the two flat spacer plates and is in contact with the two flat spacer plates. The second reflective plane is arranged parallel to the single plane containing the two flat spacer plates and is in contact with the two flat spacer plates. The first and second reflective planes are arranged on opposite sides of the single plane.

[0007] In some exemplary embodiments disclosed herein, an optical device includes a first element having a first reflective plane, a second element having a second reflective plane opposite to the first reflective plane, and two flat spacer plates of thickness H arranged in a single plane having opposing reflective spacer plate sidewalls. The two flat spacer plates are positioned between the opposing first and second reflective planes, with the opposing first and second reflective planes separated by a thickness of H.

[0008] In some exemplary embodiments disclosed herein, an optical device includes two flat plates, each having a reflective plane, and two flat spacer plates of thickness H, each having a reflective sidewall. The two flat plates and the two flat spacer plates are arranged as a stack of two plates having reflective planes facing each other and two flat spacer plates arranged in a single plane, with opposing reflective sidewalls and a gap between the two reflective sidewalls of the two flat spacer plates, and are positioned between the two flat plates. The opposing reflective planes of the two flat plates and the opposing reflective sidewalls of the two flat spacer plates define an optical tunnel passage having a transverse dimension H with respect to a single plane.

[0009] In some exemplary embodiments disclosed herein, a method for manufacturing an optical tunnel is disclosed. Two planes are coated with a reflective coating to define two reflective planes. At least one sidewall of each of two flat spacer plates is coated with a reflective coating to define a spacer plate, each having a reflective sidewall. The two planes and the two spacer plates are fixed together with the opposing reflective sidewalls of the two planes and the two flat spacer plates arranged in a single plane between the two opposing planes. In this way, the optical tunnel passage is defined by the two opposing planes and the two opposing reflective sidewalls. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows a schematic end view of an optical tunnel. [Figure 2] Figure 2 schematically shows the cross-section SS shown in Figure 1. [Figure 3] Figure 3 schematically illustrates the manufacturing process for producing the optical tunnels shown in Figures 1 and 2. [Figure 4] Figure 4 shows an exploded view of the SS cross-section, illustrating an alternative tapered optical tunnel. [Figure 5] Figure 5 shows an alternative tapered optical tunnel using an SS cross-section. [Modes for carrying out the invention]

[0011] A method for manufacturing a rectangular optical tunnel, in which four glass plates are arranged to form a rectangle with the highly reflective surface of the inwardly positioned glass plates, thereby forming the inner surface of the optical tunnel, is effective for typical optical tunnel sizes, such as those with an aperture area of ​​approximately 1 square centimeter to several square centimeters or more. However, this method has been found to be difficult to manufacture smaller optical tunnels with cross-sectional areas on the order of sub-millimeters to several square millimeters due to the cumbersome handling, positioning, and assembly of the constituent glass plates. The embodiments disclosed herein offer improved manufacturability through improved handling and easier positioning and assembly of components. The embodiments disclosed herein are also scalable for high-volume manufacturing. Furthermore, the embodiments disclosed herein are readily applicable to tapered optical tunnels.

[0012] Referring to Figure 1, an end view of the optical tunnel 8 is shown. Figure 2 shows the cross section SS shown in Figure 1. The optical tunnel 8 includes a first element 10 and a second element 12. The first element 10 has a first reflective plane 14, and the second element 12 has a second reflective plane 16. In a preferred embodiment, the two elements 10 and 12 are flat plates, for example, flat glass plates. The optical tunnel 8 further includes two flat spacer plates 20 and 22. The flat spacer plate 20 has a reflective sidewall 24, and the flat spacer plate 22 has a reflective sidewall 26. In a preferred embodiment, the two flat spacer plates 10 and 12 are flat glass plates.

[0013] The reflective surfaces 12, 14 and reflective sidewalls 24, 26 preferably have high reflectivity, for example, reflectivity r > 90%, more preferably r > 95%, and even more preferably r > 98%. For example, each of the reflective surfaces 14, 16 and reflective sidewalls 24, 26 may include a reflective multi-layer optical interference filter coating designed using conventional interference filter design methods to provide a desired high reflectivity for a design reference spectral wavelength or wavelength range. In non-limiting examples, the reflective surfaces 14, 16 and sidewalls 24, 26 may include a silicon (a-Si:H) replacement layer and SiO2, silicon oxynitride (SiO2). x N y The interference filter coating may consist of a dielectric with a lower refractive index, such as tantalum pentoxide (Ta2O5), niobium pentoxide (Nb2O5), or titanium dioxide (TiO2). Instead of the interference filter, the reflective surfaces 14,16 and reflective sidewalls 24,26 may contain reflective metals such as silver (Ag, up to r=98% depending on wavelength), aluminum (Al, up to r=95% depending on wavelength), and may have even higher reflectivity provided optionally by surface deactivation or other surface treatment / coating layers. In some embodiments, the reflective coatings of the reflective surfaces 14,16 and reflective sidewalls 24,26 have a reflectivity of at least 0.95 over a wavelength range including 400 to 700 nanometers. More generally, the reflective surfaces 14, 16 and reflective sidewalls 24, 26 preferably have a reflectance of 0.9 or more (i.e., 90% or more) with respect to the design wavelength or wavelength range, and more preferably have a reflectance of 0.95 or more (i.e., 95% or more) with respect to the design wavelength or wavelength range.

[0014] As best illustrated in Figure 1, in the optical tunnel 8, two flat spacer plates 20, 22 are arranged on a single plane (e.g., the plane of the illustrated cross-section SS) with their reflective sidewalls 24, 26 facing each other and a gap W (shown in the cross-section SS in Figure 2) between the two opposing reflective sidewalls 24, 26. This gap W defines the width W of the optical tunnel 8. Note that the drawings are schematic. Generally, the reflective coating applied to form the reflective surfaces 14, 16 and reflective sidewalls 24, 26 is assumed to have a negligible thickness on the order of microns. If the thickness of the coating is not negligible, the position of each reflective surface 14, 16 and each reflective sidewall 24, 26 is defined as the upper exposed reflective surface of the reflective coating.

[0015] Furthermore, within the optical tunnel 8, the first reflective plane 14 is positioned parallel to a single plane that accommodates the two flat spacer plates 20, 22 (i.e., parallel to the cross-sectional plane of cross-section SS shown in Figure 1). Additionally, the two reflective planes 14, 16 are positioned opposite each other on either side of the single plane (i.e., the exemplary cross-sectional plane SS) and are in contact with the two flat spacer plates 20, 22. This arrangement gives the optical tunnel 8 a rectangular cross-section having the aforementioned width W and a height H equal to the thickness of the two flat spacer plates 20, 22 (assuming they have the same thickness within design tolerances). Generally, the height H and width W do not need to be equal, but these dimensions can be equal if appropriate for the design of a particular optical tunnel. The optical tunnel 8 has a rectangular passage 30 of dimensions H × W, defined by (1) two opposing reflective surfaces 14, 16 of a first element 10 and a second element 12 having a thickness H, and (2) two opposing reflective sidewalls 24, 26 of two flat spacer plates 20, 22. The exemplary sidewalls 24, 26 are straight and perpendicular to the reflective surfaces 14, 16, although this is not strictly necessary. It should be noted that any deviation from a straight orthogonal sidewall profile and orientation should be analyzed in terms of its impact on optical loss. On the other hand, having reflective sidewalls 24, 26 with some convex or concave curvature can be advantageously aided in optical mixing.

[0016] In the SS cross-section of Figure 2, the two flat spacer plates 20 and 22 are depicted as opaque, so it should be noted that the reflective surface 14 of the underlying first element 10 is not visible, except for the gap W between the reflective surfaces 24 and 26 of the two flat spacer plates 20 and 22. Naturally, if the two flat spacer plates 20 and 22 were made of a transparent material such as glass, the SS cross-section would actually have the reflective surface 14 visible through the transparent flat spacer plates 20 and 22. However, the two opposing reflective surfaces 14 and 16 and the two opposing reflective sidewalls 24 and 26 together form a continuous perimeter of the rectangular passage 30 with dimensions H × W. Therefore, the transparency or opacity of the flat spacer plates 20 and 22, or even the transparency or opacity of the elements 10 and 12, does not affect the optical properties of the rectangular passage 30, which is an optical light tunnel.

[0017] Next, with reference to Figure 3, the manufacturing process for producing the optical tunnels 8 of Figures 1 and 2 will be described. In this exemplary example, the first element 10 and the second element 12 are produced from a glass plate 40 (e.g., a glass microscope slide, as a non-limiting exemplary example) by coating two planes of the glass plate 40 with a reflective coating to define two reflective planes 14, 16. In some embodiments, this can be done by coating a single plane of a larger glass plate, which is then cut (i.e., diced) to form individual glass plates 10, 12 having the reflective coatings 14, 16. Naturally, scalability is easily achieved, as large-scale industrial-scale coating machines can coat many such elements in a single batch process.

[0018] In parallel, two flat spacer plates 20, 22 are formed as individual components of a potentially large-scale batch process. As schematically shown in FIG. 3, two glass plates 42, each of thickness H, are assembled with other alternative glass plates 42 to form a plate stack 44. In this stack, all side walls on one side of stack 44 are parallel and face the same direction. Thus, all these side walls can be coated in a single batch coating process to produce a coated stack 46 with coated side walls. Further, by making the glass plates 42 of a thinner thickness H, it becomes possible to assemble more such plates within stack 44. As a result, scalability substantially increases with a decrease in thickness H (and thus a decrease in the dimension H of the resulting optical tunnel passage 30). Then, the individual plates of the coated stack 46 are disassembled, and a coated plate, which is any two components of the alternative plate stack 46, is selected as two flat spacer plates 20, 22 each having a coated side wall 24, 26.

[0019] Finally, as shown in FIG. 3, the four components, the pieces 10, 12, 20, 22, are fixed with two opposing planes 14, 16, two flat spacer plates 20, 22 disposed in a single plane between the two opposing planes 14, 16, and opposing reflective side walls 24, 26 facing each other, whereby the optical tunnel passage 30 is defined by the two opposing planes 14, 16 and the two opposing reflective side walls 24, 26.

[0020] Continuing to refer to FIG. 3, in an alternative embodiment shown in parentheses, the stack 44 is coated on two opposing sides to produce a coated stack 47. The advantage of this approach is to improve handling and reduce the potential for assembly errors.

[0021] The optical tunnel passage 30 has a rectangular cross-section of dimensions H × W, where dimension H is constant in the transverse direction to a single plane (i.e., the cross-sectional plane of section SS in exemplary Figures 1 and 2), and dimension W is constant in the direction parallel to the single plane. When the two opposing side walls 24, 26 are parallel to each other, dimensions H and W are constant along the entire length of the optical tunnel. Dimension H is determined by the thickness of the two spacer plates 20, 22 (ignoring the thickness of any glue or other adhesive that may be optionally applied to join the surfaces 14, 16 to the spacer plates 20, 22. In some embodiments, no adhesive is used, and instead, the assembly is clamped together). This dimension H can be as small as the actual thickness of the stock glass plate or plate 42 from which it is cut or obtained. For example, in some intended embodiments, H is 4 millimeters or less, but larger values ​​for H are also possible. Similarly, the gap W between the opposing reflective side walls 24, 26 can be almost arbitrarily small. For example, a mandrel (or spacer) can be inserted during assembly to create a specified gap W, which can then be removed after assembly. Thus, the gap W may be 4 millimeters or less in some embodiments, but larger values ​​of the gap W are also conceivable. In some embodiments, the dimensions of the opening H × W are designed to specify a sub-millimeter opening; that is, H and / or W may be less than 1 millimeter.

[0022] Referring to FIGS. 4 and 5, an embodiment of the modification is shown by an exploded cross-sectional view (FIG. 4) along cross-section S-S and an assembled cross-sectional view (FIG. 5) along cross-section S-S. In this embodiment, the two rectangular spacer plates 20, 22 are replaced by wedge-shaped spacer plates 120, 122. As a result, the two flat spacer plates 120, 122 are arranged in a single plane (e.g., cross-section S-S) with the opposing reflective sidewalls 124, 126 angled with respect to each other. (Alternatively, although not shown in the modification, rectangular plates 24, 26 can be used to tilt the plates relative to each other to define an angle.) In this way, as best shown in FIG. 5, a tapered optical tunnel passage is defined between the opposing first and second reflective planes (the same as in the embodiments of FIGS. 1 and 2). The opposing reflective sidewalls 124, 126 are angled with respect to each other. The tapered optical tunnel passage has a constant dimension H in a transverse direction with respect to the single plane. Dimension H, similar to the embodiments of FIGS. 1 and 2, is defined by the thickness of the flat spacer plates 120, 122. However, in the embodiments of FIGS. 4 and 5, the constant dimension W (resulting from the opposing sidewalls 24, 26 being parallel to each other) of the embodiments of FIGS. 1 and 2 is replaced by a non-constant dimension that linearly varies along the length of the optical tunnel passage due to the angle of the opposing reflective sidewalls 124, 126. More generally, for example, a non-linear taper can be achieved by having opposing reflective sidewalls with a parabolic or other curvature that are cut using a diamond saw or other precision glass cutting machine.

[0023] In an exemplary embodiment, the plates 10, 12, 20, 22 are glass plates, but plates of any other material, such as metal plates, can be used. In the case of a metal plate made of a metal having a sufficiently high reflectivity (e.g., aluminum), the individual reflective coatings can be omitted.

[0024] It should be understood that the various items and other features and functions disclosed above, or their substitutes, may, preferably, be combined with many other different systems or applications. It should also be understood that various currently unforeseen or unexpected substitutes, modifications, variations, or improvements may be made later by those skilled in the art, and these too are intended to be covered by the following claims.

Claims

1. A first flat plate having a first reflective surface, A second flat plate having a second reflective surface, Two flat spacer plates, each having a reflective side wall, An optical device comprising, The two flat spacer plates are arranged in a single plane such that their reflective sidewalls face each other and there is a gap W between the opposing reflective sidewalls. The first reflective surface is positioned parallel to the single plane including the two flat spacer plates and is in contact with the two flat spacer plates. The second reflective surface is positioned parallel to the single plane including the two flat spacer plates and is in contact with the two flat spacer plates. The first reflective surface and the second reflective surface are arranged on both sides of the single plane. The two flat spacer plates each have a thickness H, The first flat plate, the second flat plate, and the two flat spacer plates are clamped together to form an assembly that does not contain adhesive. The assembly has an optical tunnel passage defined by the first reflective surface, the second reflective surface, and the opposing reflective sidewalls. The optical device is characterized in that the optical tunnel passage has a constant height dimension equal to the thickness H in the direction traversing the single plane.

2. The optical device according to claim 1, characterized in that the first flat plate is arranged parallel to the single plane, and the second flat plate is arranged parallel to the single plane.

3. The first flat plate, the second flat plate, and the two flat spacer plates are each glass plates. The optical device according to claim 1, characterized in that the first reflective surface, the second reflective surface, and the opposing reflective sidewalls are defined by reflective coatings provided on each of the glass plates.

4. The first flat plate, the second flat plate, and the two flat spacer plates are each made of metal. The optical device according to claim 1, characterized in that the first reflective surface, the second reflective surface, and the opposing reflective sidewalls are each defined by the respective metal plates.

5. The optical device according to any one of claims 1 to 4, characterized in that the optical tunnel passage has a rectangular cross-section with dimensions H × W.

6. The optical device according to any one of claims 1 to 5, characterized in that the gap W is constant.

7. The first reflective surface is not parallel to the second reflective surface, The optical device according to any one of claims 1 to 5, characterized in that the gap W is not constant.

8. The optical device according to claim 7, characterized in that the opposing reflective sidewalls each have a curvature such that the change in the gap W over the length of the optical tunnel passage is not linear.

9. The optical device according to claim 7, characterized in that the opposing reflective sidewalls are arranged at a predetermined angle to each other such that the gap W changes linearly over the length of the optical tunnel passage.

10. A first flat plate having a first reflective surface, A second flat plate having a second reflective surface, Two flat spacer plates, each having a reflective side wall, An optical device comprising, The two flat spacer plates are arranged on a single plane such that their reflective sidewalls face each other and there is a gap W between the opposing reflective sidewalls, and each of the two flat spacer plates has a thickness H. The first reflective surface is positioned parallel to the single plane including the two flat spacer plates and is in contact with the two flat spacer plates. The second reflective surface is positioned parallel to the single plane including the two flat spacer plates and is in contact with the two flat spacer plates. The first reflective surface and the second reflective surface are arranged on both sides of the single plane. The first flat plate, the second flat plate, and the two flat spacer plates are fixed together to form an assembly such that the first reflective surface contacts the two flat spacer plates and the second reflective surface contacts the two flat spacer plates. The assembly has an optical tunnel passage defined by the first reflective surface, the second reflective surface, and the opposing reflective sidewalls, and the optical tunnel passage has a certain height dimension. There is no adhesive between the first reflective surface, the second reflective surface, and the opposing reflective side walls such that the thickness H of the opposing reflective side walls is equal to the constant height dimension of the optical tunnel passage. An optical device characterized in that the thickness H and the constant height dimension are measured in a direction traversing the single plane.

11. The optical device according to claim 10, characterized in that the first flat plate, the second flat plate, and the two flat spacer plates are clamped and fixed together.

12. The optical device according to claim 10 or 11, characterized in that the optical tunnel passage has a rectangular cross-section with dimensions H × W.

13. The optical device according to any one of claims 10 to 12, characterized in that the gap W is constant over the length of the optical tunnel passage.

14. The optical device according to any one of claims 10 to 12, characterized in that the gap W changes linearly over the length of the optical tunnel passage.

15. The optical device according to claim 14, characterized in that the two flat spacer plates are wedge-shaped such that the opposing reflective sidewalls are arranged at a predetermined angle to each other.

16. The optical device according to any one of claims 10 to 15, characterized in that the two flat spacer plates, the first flat plate, and the second flat plate are each made of glass plates provided with a reflective coating.

17. The optical device according to any one of claims 10 to 15, characterized in that the two flat spacer plates, the first flat plate, and the second flat plate are each made of a metal plate.

18. A method for forming an optical tunnel, The steps include: placing a first spacer plate on the first reflection plane of the first element; A step of arranging a second spacer plate on the first reflective plane, wherein the first spacer plate and the second spacer plate each have opposing reflective side walls, are separated by a gap W, and each has a thickness H, A step of arranging a second element having a second reflective plane on the first spacer plate and the second spacer plate, wherein the second reflective plane faces the first reflective plane and is spaced apart from the first reflective plane by a dimension H equal to the thickness H of the first spacer plate and the second spacer plate, To form the optical tunnel having an optical tunnel passage with dimensions H x W, the steps include fixing the first spacer plate, the first element, the second spacer plate, and the second element together, Includes, A method characterized by not using adhesive to fix the first spacer plate, the first element, the second spacer plate, and the second element together.

19. The method according to 18, characterized in that the step of fixing the first spacer plate, the first element, the second spacer plate, and the second element together is performed by clamping.

20. The first element consists of a first flat plate, and the second element consists of a second flat plate. The method according to 18 or 19, characterized in that the first reflective plane of the first flat plate is parallel to the second reflective plane of the second flat plate.

21. The aforementioned fixing step is, The steps include inserting a spacer into the space between the first spacer plate, the first element, the second spacer plate, and the second element, The steps include clamping the first spacer plate, the first element, the second spacer plate, and the second element together, The steps include removing the spacer from the optical tunnel passage, The method according to any one of claims 18 to 20, characterized by including

22. A step of forming a first element by applying a first reflective coating to a first plane of a first glass plate, wherein the first reflective coating forms the first reflective plane of the first element. A step of forming the second element by applying a second reflective coating to a second plane of a second glass plate, wherein the second reflective coating forms the second reflective plane of the second element. A step of forming the first spacer plate by applying a third reflective coating to the first side wall of the third glass plate, wherein the third reflective coating forms the reflective side wall of the first spacer plate, A step of forming the second spacer plate by applying a fourth reflective coating to the second side wall of the fourth glass plate, wherein the fourth reflective coating forms the reflective side wall of the second spacer plate, The method according to any one of 18 to 21, further comprising:

23. The method according to any one of 18 to 22, characterized in that the thickness H of the first spacer plate and the thickness H of the second spacer plate are constant.

Images