JP2011507012A - Optical face plate and manufacturing method thereof - Google Patents

Abstract

  An optical face plate and a method for manufacturing the same are disclosed. The optical faceplate (10) includes a substrate (12) having a major surface and an array of optical fibers (15) stamped on the substrate. The optical fiber has a depth that depends on the layer of material deposited on the substrate forming the optical fiber, the depth of the mold or stamping feature, and the number of processing / embossing steps. The method includes forming a layer on a substrate having a major surface and treating the layer to form an array of optical fibers disposed laterally on the major surface.

Description

  This disclosure relates to optical faceplates used in various applications including light and image transmission, and more particularly to optical faceplates employing stamped optical fibers disposed laterally on an optical substrate and It relates to the manufacturing method.

  Fiber optic faceplates that transmit light from the source or to the detector are used for high resolution zero-thickness light and image transmission in a variety of applications, including CCD / CMOS coupling, laser array / fiber array coupling , CRT / LCD displays, image enhancement, remote viewing, field flattening, X-ray imaging, and molecular diagnostics such as genomic, proteomics, drug delivery and microfluidic systems. While the advantages of optical fibers are clear and proven, various problems and limitations exist in manufacturing these plates.

  The current problem in manufacturing optical faceplates is the difficulty in building thin optical fibers to the desired diameter, bonding them together, then cutting and polishing the bundled fibers to the desired thickness Including sex. There is also room for improvement when manufacturing faceplates with fibers having smaller sizes (less than 10 microns) to control parallel alignment and diameter between individual fibers. Furthermore, current manufacturing processes do not provide an efficient way to vary the center spacing between fibers, and do not provide fibers of different shapes (eg, ellipse, square, hexagon, octagon).

  Another recognized problem is providing an accurate alignment of the fiber to the detector pixels, such as CCD and CMOS sensors, to prevent crosstalk. The complexity of conventional faceplates results in expensive manufacturing processes.

  According to the present embodiment, an optical face plate and a manufacturing method thereof are disclosed. The optical faceplate includes a substrate having a major surface and an array of optical fibers stamped on the substrate. The optical fiber has a depth that depends on the layer of material deposited on the substrate forming the optical fiber, the depth of the mold or stamping feature, and the number of processing / embossing steps. The method includes forming a layer on a substrate having a major surface and treating the layer to form an array of optical fibers disposed laterally on the major surface.

  These and other objects, features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments to be read in conjunction with the accompanying drawings.

1 is a perspective view of an optical face plate embossed on a substrate according to one embodiment. FIG. FIG. 6 is a perspective view of an optical faceplate with deposited optical fibers stamped on a substrate according to another embodiment. FIG. 3 is a perspective view of the optical faceplate of FIG. 1 or 2 with a light blocking material deposited according to one embodiment. 1 is a perspective view of an optical faceplate having a functional material (eg, phosphor) deposited on an optical fiber according to one embodiment. FIG. FIG. 5 is a perspective view of an optical faceplate having functional material (eg, an affinity probe for a specific target) deposited on an optical fiber according to another embodiment. Sectional drawing of a substrate having a solvent layer on which activated molecules are formed. FIG. 6B is a cross-sectional view of the solvent layer of FIG. 6A converted into a gel. FIG. 6B is a cross-sectional view of the gel of FIG. 6B embossed using a rubber stamp to emboss the fiber into a solid structure. 1 is a cross-sectional view illustrating a solid structure that forms an optical fiber according to one exemplary embodiment. Sectional drawing of the board | substrate which has UV or a thermosetting layer. FIG. 7B is a cross-sectional view of the UV or thermosetting layer of FIG. 7A that is imprinted using a template and then exposing the UV or thermosetting layer to radiation to initiate polymerization. 1 is a cross-sectional view illustrating the removal of a template that leaves a solid structure forming an optical fiber according to one exemplary embodiment. 1 is a cross-sectional view of a substrate having an array of optical fibers filled with a filler material. FIG. 1 is a cross-sectional view of a substrate having a solid structure filled with a filler material having a layer to be imprinted. FIG. 8B is a cross-sectional view of the layer of FIG. 8B that is imprinted using a template and then solidifying the curable resin. 1 is a cross-sectional view illustrating the removal of a template that leaves a solid structure forming an optical fiber according to one exemplary embodiment. 1 is a cross-sectional view of a solid deposited structure that forms an optical fiber according to one exemplary embodiment after removal of filler material. FIG. 1 is a schematic diagram illustrating an exemplary application of an optical faceplate according to one exemplary embodiment. Schematic showing a setup without a faceplate. FIG. 3 is a block / flow diagram illustrating an exemplary method of manufacturing an optical faceplate according to the present principles.

  Hereinafter, a preferred embodiment will be described in detail with reference to the drawings.

  The present disclosure includes, but is not limited to, charge coupled device (CCD) / complementary metal oxide semiconductor (CMOS) coupling, laser array / fiber array coupling, cathode ray tube (CRT) / liquid crystal display (LCD) display, image enhancement, Optical faceplates that can be employed in applications including remote viewing, field flattening, X-ray imaging, and molecular diagnostics such as genome, proteomics, drug delivery and microfluidic systems are described. Currently, such plates are manufactured by building thin optical fibers to the desired diameter, bonding them together, then cutting and polishing the device to the desired thickness. This is a difficult process due to various limitations. In accordance with the present principles, a method for manufacturing an optical plate is disclosed. The method involves embossing a structure with a desired height and aspect ratio on top of a desired substrate, which can be a functional unit (such as a detector). This may be followed, if necessary, by filling the area around the stamped fiber with a low refractive material or other material. The functional material may be deposited on the fiber as well. These functional materials may be, for example, affinity probes for specific targets that are deposited on the optical faceplate.

  It should be understood that the present invention is described in terms of an optical faceplate with stamped optical fibers. However, the teachings of the present invention are more widely applicable to array-based attachment methods for fibers that are transverse to the substrate carrying or holding the fibers. The fiber may be mounted, placed or placed on the substrate using a number of different technologies. The embodiments disclosed herein are preferably manufactured using a printing process. However, lithographic imaging and processing may be employed. Other processing techniques can also be envisaged.

  It should be understood that the illustrative example of an optical faceplate may be adapted to include additional electronic / optical components. These components may be integrally formed on the substrate, or may be mounted on the substrate or other components (eg, on a fiber). The elements shown in each figure can be realized by a combination of various hardware, and provide functions that can be combined into a single element or a plurality of elements.

  Referring to the drawings in which like reference numbers indicate the same or similar elements, and referring first to FIG. 1, the optical faceplate 10 is a plurality of stamps that are embossed on top of the substrate 12 in a desired pattern or array 15. A substrate 12 with an optical fiber 14 is included. The substrate 12 may be a functional unit 16 such as a pixel, a pixel array, a detector, a sensor, or the like, or the functional unit 16 may be formed thereon. If a detector or sensor is employed on the substrate 12, quality checking or testing of the fiber optic array 15 is easier because it is easier to detect the functionality of the final product. The fiber 14 preferably has a high aspect ratio, for example a width to length ratio of 1: 2 to 1:10 or more.

  By printing or embossing the optical faceplate 10, the above limitations in bundling conventional optical fibers, bonding them together, then cutting and polishing them to the desired thickness are effective. Will be dealt with. The fibers 14 formed according to the present principles are particularly small in diameter (eg, less than 10 microns) and can be individually aligned and more easily manufactured. The method is also suitable for producing fibers with nanometer dimensions (nanofibers). The manufacturing method also allows control of various array dimensions, such as the center spacing between the fibers 14, the shape of the fiber (eg, ellipse, square, hexagon, octagon, etc.), and the fiber tip shape. Such dimensions, shapes and spacings are advantageously pre-patterned in a lithographic mask operation or predetermined within a mold / stamp.

  It should be understood that this principle provides great flexibility in the manufacture of optical fibers. For example, the cross-sectional shape of the fibers and the spacing between the fibers may be varied on the same device or substrate. That is, the density of the fiber and the individual size of the fiber may be varied on the surface. Also, the cross-sectional shape and width may be varied and mixed on the surface. Furthermore, the upper surface shape of the fiber can be changed to a dome shape, a flat shape, a pyramid shape, a curvature, or the like. Further, the fiber dimensions may vary along the fiber axis. Such structures may be varied and mixed along the surface. For example, a tapered fiber may be manufactured.

  Accurate placement of the optical fiber 14 relative to the substrate 12 is effectively achieved. For example, if the substrate 12 includes a detector or source such as a CCD or CMOS sensor, precise positioning of the fiber 14 can be provided at a specific location on the substrate 12 where the characteristics can be optimized or improved. . Furthermore, the coupling of the optical faceplate to the source or detector is improved, resulting in efficient transmission efficiency and reduced cost. The fiber can be chemically bonded to the surface. This can be achieved by treating the surface with reactive molecules that can react subsequently with the layer. It can also be just a physical bond.

  Various materials can be used in forming the fiber 14. In a particularly useful embodiment, a sol-gel material that exhibits low polymerization shrinkage and chemically attaches to the surface may be employed. In one embodiment, the liquid material is deposited (eg, spun on) and solidified by evaporation of the solvent and / or crosslinking by heat or light. For optical faceplate 10, these materials have the improved optical properties desirable for this application (eg, optimal numerical aperture, high transmission) while being thermally and chemically stable ( There is no deterioration or discoloration). Examples of curable materials include (meth) acrylates, epoxy oxetanes, vinyl ethers, alkoxides such as tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), methyltrimethoxysilane (MTMS) or other suitable materials. May be selected from the set.

  With reference to FIG. 2, a deposited fiber optic faceplate 20 is illustratively shown. The first layer 28 includes a first material that may be deposited or spun on the substrate 12. The second layer 26 is formed on the first layer 28. The processing of layers 26, 28 may be performed in separate steps or simultaneously depending on the type of material employed for each layer and the method used to process the layers. For example, if a stamping process is employed, both layers 26, 28 may be stamped simultaneously to form the deposited fiber 24. If a lithographic process is employed, the layers may be etched at the same time, or may be etched in a separate step if the etching chemistry needs to be adjusted for different layers.

  The substrate 12 of FIG. 2 may include a pixelated photosensor 16 such as a CMOS or CCD device formed in or on the substrate 12. The fiber 24 is used to guide light to a sensor that is configured to guide light generated by, for example, a phosphor layer on top of the fiber. If the fiber needs to have an aspect ratio that is not obtainable with a single imprint operation, the deposited fiber configuration shown in FIG. 2 can be used. The deposited fibers 24 may include different materials and may have different optical properties and dimensions. Those skilled in the art will appreciate that one of the layers may be used to attenuate radiation (light, x-rays, etc.) or condition the light and / or radiation (eg, filter certain wavelengths, etc.) Will understand. In one embodiment, layer 26 may remain continuous, with no fiber formed therein, and only fiber formed in layer 28.

  It should be understood that multiple layers may be deposited on each other by a number greater than one. Further, the cross-section of the deposited fiber 24 may be formed coaxially as shown in FIG. However, the cross-section of the deposited fiber 24 may be formed with different cross-sectional areas between layers, or may have a center offset between layers.

  Referring to FIG. 3, the region between the fibers 14 or 24 may be left empty or filled or partially filled with material 32. Material 32 may include low refractive index materials, radiation blocking materials (eg, light blocking materials, X-ray blocking materials including heavy metals and their ions) or other functional materials or structures. For example, highly reflective or absorptive materials that may contain particles of any size are used to fill structures outside the fiber optic faceplate 10 or 20 to obtain high image quality for CCD or CMOS imagers May be. Material 32 may also be employed to protect fibers 14 and 24 from stress / strain due to handling and manipulation. The material 32 also treats the upper portion of the fiber 14 or 24 while protecting the lower portion of the fiber 14 or 24 (eg to form additional features as described below with reference to FIGS. 4 and 5 or rough or dirty). It may be employed as a mask to reveal for etching) to clean the surface.

  Referring to FIG. 4, fiber optic faceplate 10 (or 20) may be used as a luminescent material, phosphor (phosphor), scintillator material or other material when the application includes x-ray imaging or other modalities. A functional material 42 may be included. Preferably, this material (eg, phosphor) 42 may be disposed in the upper region of the fiber 14. These structures 42 may be illuminated under given conditions.

  Referring to FIG. 5, a functional material 52 such as an affinity probe 54 for a particular target can be similarly deposited on the optical faceplate 10 or 20. The specific target affinity probe 54 can be deposited on the optical faceplate 10 or 20 in a number of ways including contact, drop, spot or by any other deposition technique. Demobilization of the specific target affinity probe 54 on the optical faceplate can be accomplished in different ways including chemical binding of the probe 54 to the faceplate 10 or 20. Probe 54 may include DNA, RNA, protein, cells, tissues or biomolecules of interest or different biological receptors for detecting any type of organism.

  Optical faceplates can be used for high biodiagnosis throughput. The components may be employed in many applications such as, for example, genome, proteomics, drug delivery and microfluidic systems. Optical faceplates have the advantage of having a very high number of optical elements and reaction sites. Optical faceplates provide uninterrupted separation of reaction sites via microwells or capillaries. By using optical fiber technology, excellent readout of individual optical channels can be obtained. This allows for high sensitivity, repeatability and low background fluorescence.

  With reference to FIGS. 6A to 6D, an imprint lithography / embossing method is schematically illustrated by one method for manufacturing an optical faceplate according to the present principles. Large area imprinting techniques may be employed, which are very suitable for fabricating nanometer-sized structures with a high aspect ratio at room temperature in a single deposited layer. According to this method, a flexible stamp may be employed for replicating structures from millimeter to nanometer size. This technique is very suitable for manufacturing fiber optic faceplates because it can print features with high aspect ratios from millimeters to nanometers with high accuracy. Furthermore, the manufacturing process is low cost and has industrial productivity. The proposed fiber optic faceplate production process using imprint lithography is shown here.

  Referring to FIG. 6A, 2.9 wt% TMOS, 2.6 wt% MTMS, 87.5 wt% 1-propanol, 2.3 wt% formic acid, 3.7 wt% water and 1 wt% A solidifiable liquid 62 with reactive molecules, such as 0.0 wt% methylbenzoate, is applied onto the substrate 12 by, for example, spin coating, spray coating or doctor blading. The substrate may include functional units 16, such as pixels or photosensors or the like. During this process, the solvent in the liquid 62 vaporizes and the reactive molecules begin to form a gel 66 as shown in FIG. 6B. Subsequently, the layer 68 is gently applied to the substrate 12 in a wave manner to prevent air entrainment, as described in WO2003099463 and EP1511632, which are incorporated herein by reference, as shown in FIG. 6C. The solvent in the liquid 62 may also diffuse from the gel material 66 into the stamp 70 to help leave the solid structure 72 on the substrate 12 and / or functional unit 16, as shown. The rubber stamp 70 is preferably removed by a similar wave technique and the stamp 70 is peeled off without breaking the replica. If some material remains as a dependency between structures 72, etching methods such as reactive ion etching (RIE) and / or ion beam etching may be employed. Optionally, the solid structure 72 on the substrate 12 can be filled with a light blocking material or other material such as a silver sol-gel (see, eg, FIG. 3). It is also possible to first manufacture the light blocking structure and then fill the gap with a material capable of transmitting light.

  Referring to FIGS. 7A-C, a second imprint lithography / embossing method is schematically illustrated using ultraviolet (UV) or heat sensitive materials for the manufacture of faceplates.

  Referring to FIG. 7A, UV or heat sensitive material 164 is applied onto substrate 12 by, for example, spin coating or doctor blading. The deposited layer is embossed or imprinted with stamp 170 and then exposed to radiation, as shown in FIG. 7B. Irradiation causes the resist or material 164 to crosslink or otherwise solidify. As shown in FIG. 7C, the stamp 170 is removed, leaving a fiber structure 172 on the substrate 12.

  Referring to FIG. 8, process steps used to fabricate a fiber deposition structure according to another exemplary embodiment are shown.

  Referring to FIG. 8A, the fiber array 180 is formed on the substrate 12 including the functional unit 16. The fiber array 180 is generated by imprint lithography in which the area between the fibers 14 is filled with material 182 (which may be the same as material 32 described above). Referring to FIG. 8B, a curable material 184 (eg, resist) is applied onto the filled fiber array 180 of FIG. 8A, for example, by spin coating or doctor blading. The deposited layer of FIG. 8B is embossed by stamp 170 after alignment of the stamp with respect to the substrate and then solidified to form solid structure 186, as shown in FIG. 8C. As shown in FIG. 8D, the stamp 170 is removed, leaving a fiber structure 186 on the filled fiber array 180 of FIG. 8A. The filler material 182 can later be removed by diffusing the filler material 182 into a suitable solvent or by burning off the filler material 182 to produce a deposited fiber array 188 (heat resistant or solvent resistant). Only possible if the material is used to produce a fiber array such as a sol-gel material).

  Referring to FIG. 9, in one exemplary embodiment, the fiber optic faceplate 190 may be employed in digital radiography applications. This produces good image resolution and efficient light collection and transmission characteristics compared to lenses. The optical fiber array 190 is disposed between the scintillator 192 and the CCD or CMOS imaging device 194. The X-ray source 196 generates X-rays. Although light from the X-ray scintillator tends to scatter as shown in FIG. 10, the faceplate 190 manufactured from coherent fiber optic strands according to this principle minimizes scattering and ensures image intensity and resolution. .

  While the advantages of optical fibers for digital radiography are obvious, the problem is that using conventional techniques, such fiber optic faceplates are manufactured and the fiber optic faceplate is coupled to a CCD or CMOS imager 194 and scintillator. Can exist in It is important that the fiber be aligned with the detector pixels. Distortion and response non-uniformity that degrade image quality should be reduced. A high degree of fiber alignment to the pixel is achieved by bonding or embossing the fiber to a substrate (eg, a CD or CMOS imager directly) according to the present principles. Accurate, robust and reliable attachment is provided by embossing the fiber gel or by using photolithography on the crosslinked layer.

  Furthermore, higher image quality is provided by increasing the number of fibers that carry light to each sensor pixel. For example, a 6 micron fiber diameter can provide 16 fibers for a 24 micron pixel. However, more fibers can be provided by the present principles because they can be manufactured with smaller diameter fibers (even on a nanometer scale). The density, size, shape and position of the fiber can be easily changed within the substrate.

  This principle provides accurate and robust fiber optic faceplate attachment with improved transmission efficiency, reduces distortion and response non-uniformity, and maximizes image quality and durability. In addition, the faceplate comprises fibers having smaller sizes (eg, less than 15 micrometers and up to nanometer range) and specific shapes (eg, ellipse, square, hexagon, octagon, etc.) as described above. Can be manufactured. Further, the upper surface shape of the fiber can be changed to a dome shape, a flat shape, a pyramid shape, a curvature, or the like. Furthermore, the manufacturing method according to this embodiment reduces the cost.

  In an embodiment of the present invention, the fiber optic faceplate is manufactured using a bridging material. Micrometer and nanometer structures with various shapes and high aspect ratios (1:10) are also produced on a variety of surfaces with different roughness or profiles.

  Referring to FIG. 11, a method of manufacturing an optical face plate is exemplarily shown according to the present principle. In block 202, a layer is formed on the major surface of the substrate. The layer is preferably a material capable of transmitting electromagnetic radiation at a desired wavelength or wavelength range when cured or dried. The layer may be applied by spin coating or doctor blading on the surface of the substrate. The substrate may include an imaging device (eg, a pixel). The material may include a liquid that is a solidified or cross-linked material, such as a liquid that becomes a gel after the solvent is vaporized or polymerized by heat or radiation. In one example, the layer material can solidify during the embossing of the layer. In block 204, the layers are processed to form an array of optical fibers that are disposed laterally on the major surface of the substrate. This may include forming a gel or solid during or prior to the embossing step at block 206 or curing the resist layer using radiation (eg, UV) or heat during the embossing step.

  In optional step 203, filler material may be formed around the previous layer of fibers. Thus, multiple layers may be formed to produce a deposited optical faceplate. After the processing of blocks 202-210 is complete, if necessary, the filler material is applied instead of or in addition to the radiation blocking material of (block 210). A second layer (block 202) is formed and processed according to steps 202, 204, 206, 208, 210 if necessary. This can continue for as many layers as necessary. The multiple layers form an array of optical fibers in such a manner that each layer provides a portion of the total length of the entire optical fiber.

  At block 206, the process may include embossing (stamping or embossing) the layer (s) to form an array of optical fibers. The embossing preferably includes applying a stamp, for example in the form of waves, to prevent voids and bubbles after alignment. The embossing process further includes controlling at least one of the spacing between the fibers, the fiber cross-sectional shape, and the fiber tip shape. This may be performed using features provided on the stamp.

  At block 208, the array of fibers may be etched or heated to remove material between the fibers. Etching may include, for example, a reactive ion etching process. In block 210, a radiation (light, x-ray, etc.) blocking material may be formed around the fiber array. In block 212, functional material may be deposited on top of the optical fiber. The functional material may include a luminescent material, a phosphor, and / or an affinity probe (eg, a specific target affinity probe). Other functional materials are also conceivable.

When interpreting the appended claims, it should be understood that:
a) the term “comprising” does not exclude the presence of other elements or acts than those listed in a claim;
b) the singular representation does not exclude the presence of a plurality of such elements;
c) any reference signs in the claims do not limit the scope of the claims;
d) Several “means” can be represented by structures or functions implemented in the same item or hardware or software,
e) A particular sequence of operations is not intended to be essential unless specifically stated.

  While preferred embodiments for optical faceplates and fabrication methods have been described (these are illustrative and not intended to be limiting), modifications and variations can be made by those skilled in the art within the scope of the above teachings. Therefore, it should be understood that changes may be made in the specific embodiments disclosed within the scope and spirit of the embodiments disclosed herein as bounded by the appended claims. Details have been set forth as specifically required by patent law, but what is desired to be protected and claimed by language patents is set forth in the claims.

Claims (25)

A method for manufacturing an optical faceplate, comprising:
Forming a layer on a substrate having a major surface;
Treating the layer to form an array of optical fibers disposed laterally and attached to the major surface.   The method of claim 1, wherein forming the layer includes a component that forms a crosslink.   The method of claim 1, wherein the layer forming the crosslink comprises a UV / thermosetting layer and a gel layer.   Forming the layers includes forming a plurality of layers and treating the layers to form an array of optical fibers, wherein each layer provides a portion of the total length of the optical fiber. The method of claim 1, comprising processing the plurality of layers to form an array of fibers.   The method of claim 1, wherein the processing includes embossing the layer to form an array of optical fibers.   The method of claim 5, wherein the processing includes employing a flexible stamp.   The method of claim 5, wherein the embossing includes controlling at least one of a spacing between fibers, a cross-sectional shape of the fiber, and a tip shape of the fiber.   The method of claim 1, further comprising etching the array of fibers to remove material between the fibers.   The method of claim 1, further comprising forming a radiation blocking material around the array of fibers.   The method of claim 1, further comprising depositing a functional material on top of the optical fiber.   The method of claim 10, wherein attaching a functional material on top of the optical fiber comprises attaching a luminescent material, a phosphor, an affinity probe, or a combination thereof. A method for manufacturing an optical faceplate, comprising:
Applying a layer on the substrate,
Forming an array of optical fibers by applying embossing and embossing the layer to solidify the layer in the presence of the embossing.   The method of claim 12, wherein the layer comprises a crosslinked material. The layer comprises a liquid material;
13. The method of claim 12, further comprising at least partially solidifying the layer prior to the embossing.   Forming a plurality of layers, and further processing the layers to form a deposited array of optical fibers in a manner that each of the plurality of layers provides a portion of the total length of the optical fiber. Item 13. The method according to Item 12.   The method of claim 12, further comprising etching the array of fibers to remove material between the fibers.   The method of claim 12, further comprising forming a radiation blocking material around the array of fibers. Further comprising depositing a functional material on top of the optical fiber;
The method of claim 12, wherein the functional material comprises one of a luminescent material, a phosphor, and an affinity probe. An optical faceplate,
A substrate having a major surface;
An array of optical fibers embossed on the substrate, the optical fiber having a length determined by the layer thickness of the material deposited on the substrate forming the optical fiber, and / or An optical face plate having a length determined by a depth of a feature relating to a stamp used for embossing the optical fiber.   The optical face plate of claim 19, wherein the substrate includes an optical sensor.   The optical faceplate of claim 19, further comprising a radiation blocking material formed around the array of fibers.   20. The optical faceplate of claim 19, further comprising a functional material on top of the fiber, the functional material comprising one of a luminescent material, a phosphor, and an affinity probe.   The optical face plate according to claim 19, wherein the layer includes a plurality of layers, and the total length is determined according to the plurality of layers.   The optical faceplate of claim 19, wherein the optical fiber comprises an aspect ratio of at least 1:10 width and length.   The optical face plate of claim 19, wherein the optical fiber has a non-circular cross-sectional shape.

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