Reflector for curing optical fibers and method of using same

Abstract

An apparatus for curing a coating composition disposed on a glass optical fiber. The apparatus includes a reflector having an interior surface that delineates a boundary of a cavity, the interior surface including a plurality of portions, each of the portions extending along a different curved profile. Further, each of the plurality of portions is configured to reflect curing light such that the reflected curing light is concentrated to a curing zone within the cavity, such that all of the reflected curing light within the curing zone has an intensity that is about 60% or greater relative to a maximum intensity of the reflected curing light. A fiber location of the glass optical fiber is positioned within the curing zone. Additionally, the plurality of portions includes at least a first portion and a second portion, the first portion having a different degree of curvature than the second portion.

Description

[0001] This application claims priority to Dutch Patent Application No. 2026720, filed October 21, 2020, which claims priority to U.S. Provisional Patent Application Serial No. 63 / 080,073, filed September 18, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] background Technical Field

[0003] This specification relates generally to reflector devices, and more specifically to reflector devices for curing glass fiber coatings and methods of using them. Background Technology

[0004] During the drawing of glass optical fibers, a polymer coating is applied to the fiber. In early drawing towers, the polymer coating was cured by heating a liquid coating composition placed on the surface of the glass fiber. For example, strong ultraviolet light sources have been used to cure the coating composition to form a polymer coating on the glass fiber. Until recently, these light sources were typically mercury plasma lamps excited by microwave energy. Such lamps can be large, consume a lot of energy, and require cooling airflow to facilitate operation. Summary of the Invention

[0005] A first aspect of this disclosure includes an apparatus for curing a coating composition disposed on a glass optical fiber. The apparatus includes a reflector having a longitudinal length and defining a cavity. The reflector includes an inner surface that defines the boundary of the cavity. The inner surface includes a plurality of portions, each of which extends along a different curvature profile. Furthermore, each of the plurality of portions is configured to reflect curing light, such that the reflected curing light is focused into a curing region within the cavity, such that all reflected curing light within the curing region has an intensity of approximately 60% or greater relative to the maximum intensity of the reflected curing light. The optical fiber of the glass optical fiber is located within the curing region. Additionally, the plurality of portions includes at least a first portion and a second portion, the first portion having a different degree of curvature than the second portion.

[0006] A second aspect of this disclosure includes an apparatus for curing a coating composition disposed on a glass optical fiber. The apparatus includes a reflector having a longitudinal length and defining a cavity. The reflector includes an inner surface that defines the boundary of the cavity, the inner surface including: a first portion extending along a first curved profile forming a first circle including a first radius and a first center located at a first central position within the cavity; a second portion extending along a second curved profile forming a second circle including a second radius and a second center located at a second central position within the cavity; and a third portion extending along a third curved profile forming a third circle including a third radius and a third center located at a third central position within the cavity. Additionally, the optical fiber position of the glass optical fiber is displaced from the first central position, the second central position, and the third central position.

[0007] A third aspect of this disclosure includes a method for curing a coating composition disposed on a glass optical fiber. The method includes: guiding a glass optical fiber through an opening into a cavity of a reflector, the glass optical fiber having the coating composition disposed thereon, the cavity being defined by an inner surface of the reflector comprising a plurality of portions, each of said portions extending along a different curvature profile. The method further includes: directing curing light from a radiation source to a curing region within the cavity, such that the curing light is reflected from the plurality of portions and focused into the curing region, such that all reflected curing light within the curing region has an intensity of about 60% or greater relative to the maximum intensity of the reflected curing light, the glass optical fiber being disposed in the curing region. The plurality of portions includes at least a first portion and a second portion, the first portion having a different degree of curvature than the second portion.

[0008] It should be understood that both the above general description and the following detailed description depict various embodiments, and they are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and form a part of this specification. The drawings illustrate the various embodiments described herein and, together with the description, serve to illustrate the principles and operation of the claimed subject matter. Attached Figure Description

[0009] Figure 1 An optical fiber forming apparatus including a curing device for curing a coating is schematically depicted according to one or more embodiments described herein;

[0010] Figure 2A A view depicting portions of a non-imaging reflector and a radiation source according to one or more embodiments described herein;

[0011] Figure 2B schematically depicted Figure 2A The various aspects of the first, second, and third parts of the non-imaging reflector depicted in the text;

[0012] Figure 3A A graph depicts a comparison of the degree of curing of coating compositions that vary with irradiation metering for non-imaging reflectors and comparative reflectors according to one or more embodiments described herein.

[0013] Figure 3B A graph depicting a comparison of the azimuth energy distribution of a non-imaging reflector and a comparator reflector according to one or more embodiments described herein;

[0014] Figure 4 A graph depicts one or more embodiments according to the present document, illustrating the azimuth curing variance of coating compositions on glass optical fibers using non-imaging reflectors, comparison reflectors, and no reflectors.

[0015] Figure 5 A cross-section of a non-imaging reflector according to one or more embodiments described herein is depicted, showing the curing light rays reflected by the non-imaging reflector;

[0016] Figure 6A The intensity distribution of the cured light reflected by the comparator relative to the glass optical fiber, according to one or more embodiments described herein, is depicted; and

[0017] Figure 6B The intensity distribution of cured light reflected by a non-imaging reflector relative to a glass optical fiber, according to one or more embodiments described herein, is depicted. Detailed Implementation

[0018] Reference will now be made in detail to embodiments of a curing apparatus comprising a non-imaging reflector for curing a coating composition applied to a glass optical fiber. Where possible, the same reference numerals will be used throughout the drawings to indicate the same or similar components. The non-imaging reflector described herein may include multiple sections having different degrees of curvature for reflecting curing light from a radiation source to the glass optical fiber. The radiation source may be an ultraviolet radiation emitting array of light-emitting diodes (LEDs), comprising multiple LEDs emitting light along an illumination axis. The non-imaging reflector described herein can provide an improved concentration of curing light from an LED array over existing reflector devices and can also provide a uniform energy distribution around the circumference of the glass optical fiber. This improvement can contribute to increased drawing speeds in fiber production and facilitate more efficient and uniform curing than existing reflector devices. Various embodiments of the non-imaging reflector and their methods of use will be described herein with specific reference to the accompanying drawings.

[0019] Throughout this specification and the following claims, reference will be made to numerous terms which shall be defined to have the following meanings:

[0020] The terms “include,” “includes,” “including,” or similar terms refer to something that covers but is not limited to, that is, inclusive rather than exclusive.

[0021] The directional terms used in this document (e.g., up, down, right, left, front, back, top, bottom) are used only with reference to the accompanying drawings and the coordinate axes provided, and are not intended to imply absolute orientation.

[0022] Unless otherwise expressly stated, any method described herein shall never be construed as requiring its steps to be performed in a particular order, nor requiring any particular orientation of any apparatus. Therefore, in any instance where a method claim does not actually describe the order of its steps, or any apparatus claim does not actually describe the order or orientation of the components, or where the claims or description do not otherwise specifically state that these steps will be limited to a particular order, or where no particular order or orientation / orientation of the apparatus components is described, no inference shall be made of any possible non-explicit basis for interpretation, including: logical matters relating to the arrangement of steps, the flow of operations, the order of components, or the orientation of components; general meanings derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0023] As used herein, the singular forms “a / an” and “the” include plural referents unless the context explicitly specifies otherwise. Thus, for example, a reference to “a component” includes aspects having two or more such components unless the context explicitly indicates otherwise.

[0024] "Optical fiber" refers to a waveguide having a glass portion surrounded by a coating. The glass portion includes a core and a cladding, and is referred to herein as "glass optical fiber".

[0025] "Ultraviolet" or "UV" refers to wavelengths greater than or equal to 200 nm and less than or equal to 450 nm.

[0026] As used herein, "being disposed on" means being in contact with, where contact refers to direct or indirect contact. For example, a primary coating may be disposed on a glass fiber and be in direct contact with the glass fiber. A secondary coating may be disposed on a glass fiber, disposed on a primary coating, indirectly in contact with the glass fiber, and in direct contact with the primary coating. A tertiary coating may be disposed on a glass fiber, disposed on a primary coating, disposed on a secondary coating, indirectly in contact with the glass fiber, and in direct contact with the secondary coating.

[0027] As used herein, the term "curable coating composition" refers to a coating composition comprising one or more curable components. As used herein, the term "curable" means that, when exposed to a suitable curing energy source, the component comprises one or more curable functional groups capable of forming covalent bonds that participate in attaching the component to itself or to other components of the coating composition. The product obtained by curing a curable coating composition is referred herein to as a cured product of the composition or a coating. The cured product may be a polymer. The curing process is energy-induced. The form of energy includes radiation or heat. In embodiments, curing occurs with radiation, where radiation refers to electromagnetic radiation. Radiation-induced curing is referred herein to as radiation curing. A radiation-curable component is a component that can be induced to undergo a curing reaction when exposed to radiation of a suitable wavelength and intensity for a sufficiently long period of time. Suitable wavelengths include wavelengths in the infrared, visible, or ultraviolet portions of the electromagnetic spectrum.

[0028] The curable component includes one or more curable functional groups. Preferred curable functional groups include olefinically unsaturated groups, such as acrylate and methacrylate groups. The curable component includes curable monomers and curable oligomers. In addition to curable monomers and / or curable oligomers, curable coating compositions typically include photoinitiators and additives. Additives include adhesion promoters, reinforcing agents, antioxidants, catalysts, stabilizers, gloss agents, property enhancers, amine synergists, waxes, lubricants, and / or slip agents. Secondary and / or tertiary coating compositions may also include pigments.

[0029] As used herein, the term “non-imaging reflector” refers to a reflector that does not reproduce a radiation source as an image, but rather concentrates the radiation from the radiation source to achieve a flux density through the volume.

[0030] As used herein, the terms “degree of curvature” and “radius of curvature” for a surface refer to the radius of curvature of an arc approximating a cross-section of the surface. In the case where the surface comprises a circular cross-section, the radius of curvature can be a constant corresponding to the radius of curvature of the entire surface within the cross-section. In the case where the surface comprises a non-circular (e.g., elliptical) cross-section, the radius of curvature can correspond to the radius of curvature of a portion of the surface calculated using an arc approximating the surface.

[0031] As described herein, mercury plasma lamps excited by microwave energy have been used to cure coatings applied to glass optical fibers. However, ultraviolet light-emitting diodes (“LEDs”) are gaining favor. LEDs offer compactness and lower energy consumption directly by reducing drive power and indirectly by reducing or eliminating the cooling airflow required by mercury plasma lamps.

[0032] While LEDs offer improvements over mercury plasma lamps, they can also present challenges in uniformly illuminating glass fibers because LED arrays may emit non-axially symmetric radiation. The inherent two-dimensional nature of an LED array means that at least some of the LEDs on the array are not positioned at the focal point of a conventional reflector. Therefore, it is difficult to correctly position the glass fiber at the point of maximum energy density, as such a point may be offset from the focal point of a conventional reflector. Additionally, conventional reflectors can suffer from anomalous azimuth energy distribution with respect to the focal point, leading to uneven curing. This defect in conventional reflectors can slow down processing time.

[0033] The embodiments disclosed herein relate to non-imaging reflectors and methods for using non-imaging reflectors to cure coatings applied to glass optical fibers, which solve at least some of the aforementioned problems of conventional reflectors.

[0034] Now for reference Figure 1 The diagram schematically depicts an optical fiber forming apparatus 100. The optical fiber forming apparatus 100 includes a furnace 102, a coating apparatus 106, and a curing apparatus 110. The furnace 102 is used to draw glass optical fibers 104. In an embodiment, the furnace 102 includes a drawing furnace that receives and heats an optical fiber preform, and further includes mechanisms (tensioners, winches, etc.) for drawing the glass optical fiber from the heated optical fiber preform to a desired size and shape. For example, in a continuous optical fiber manufacturing process, the glass optical fiber 104 is drawn from the heated preform and sized to a target diameter (typically 125 μm) by the furnace 102. In an embodiment, the glass optical fiber 104 is drawn through the optical fiber forming apparatus at a drawing speed (e.g., by one or more winches not shown). In an embodiment, the drawing speed is greater than or equal to 25 m / s. In an embodiment, the drawing speed is greater than or equal to 35 m / s to facilitate a relatively low optical fiber production time.

[0035] In one embodiment, after the glass fiber 104 is drawn from the preform, it is cooled and guided to a coating apparatus 106. The coating apparatus 106 applies a coating composition 108 to the glass fiber 104. In some embodiments, the coating apparatus 106 is separate from the furnace 102. In other embodiments, the coating apparatus 106 is part of the furnace 102. Figure 1 In the embodiments depicted, the glass fiber 104 is delivered directly from the furnace 102 to the coating apparatus 106 in a continuous manner. In other embodiments, the glass fiber 104 is delivered to the coating apparatus 106 in a continuous manner (e.g., offline coating) from a source other than a drawing tower or drawing furnace (such as from a spool). A suitable curable coating composition 108 is a polymer or acrylate-based composition (e.g., containing an acrylate compound) that can be cured by exposure to UV light. This material can be applied in a liquid state to the surface of the glass fiber 104 and then exposed to UV light for curing in the curing apparatus 110. The curable coating composition 108 can be applied in one or more layers, such as a two-layer coating system. A primary coating can be applied directly to the surface of the glass fiber 104, and, as an example, a secondary coating can be applied over a primary coating.

[0036] In an embodiment, the curable coating composition 108 includes a photoinitiator that generates a reactive substance upon exposure to radiation to initiate the curing of the curable coating composition 108. In an embodiment, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl chloride)phosphine oxide (TPO). In an embodiment, the curable coating composition 108 is disposed as a layer on the glass optical fiber 104. In an embodiment, the layer has a thickness greater than or equal to 1 μm and less than or equal to 60 μm (e.g., greater than or equal to 5 μm and less than or equal to 55 μm, greater than or equal to 10 μm and less than or equal to 50 μm).

[0037] In embodiments employing a secondary coating, two process options are feasible after the liquid primary coating composition is applied to the glass optical fiber 104. In one process option (wet-on-dry process), the liquid primary coating composition (e.g., via curing device 110) is cured to form a cured primary coating, then a liquid secondary coating composition (e.g., via a separate coating cloth device not shown) is applied to the cured primary coating, and the liquid secondary coating composition (e.g., via an additional curing device similar to or additionally via curing device 110 as described herein) is cured to form a cured secondary coating. In a second process option (wet-on-wet process), the liquid secondary coating composition is applied to the liquid primary coating composition, and both liquid coating compositions are cured simultaneously in a single curing step within curing device 110 to provide cured primary and secondary coatings. After the glass optical fiber 104 exits curing device 110, the glass optical fiber 104 is collected and stored. Collection of the optical fiber typically requires winding the fiber onto a spool and storing the spool.

[0038] In an embodiment, a tertiary coating composition may be applied to a secondary coating, and the tertiary coating composition may be cured to form a cured tertiary coating. In an embodiment, the tertiary coating is an ink layer for marking optical fibers for identification purposes and has a composition comprising pigments, and is otherwise similar to the secondary coating. The tertiary coating is applied to the secondary coating and cured. In an embodiment, the optical fiber forming apparatus 100 includes a tertiary coating device (not shown) disposed downstream of the curing apparatus 110. In an embodiment, the primary, secondary, and tertiary coating compositions may be applied and cured in a conventional continuous manufacturing process. In an embodiment, the primary and secondary coating compositions are applied and cured in a conventional continuous manufacturing process, the coated optical fibers are collected, and the tertiary coating composition is applied and cured in a separate offline process to form the tertiary coating.

[0039] Still referencing Figure 1The curing apparatus 110 initiates a curing reaction by providing heat energy to the curable coating composition 108, thereby curing the curable coating composition 108 coated on the glass optical fiber 104. The curing apparatus 110 includes a radiation source 112 and a non-imaging reflector 114. In the depicted embodiment, the non-imaging reflector 114 is integrated with the radiation source 112. In this embodiment, the non-imaging reflector 114 does not directly contact the radiation source 112 but maintains a spaced-away relationship (e.g., via a support arm, not shown, extending from the outer surface of the non-imaging reflector or a support structure). The non-imaging reflector 114 includes an inner surface 116 that defines the boundary of a cavity 118 positioned to receive the glass optical fiber 104 from the coating apparatus 106. In this embodiment, the inner surface 116 defines an open or closed cross-sectional shape. For example, in this embodiment, the inner surface 116 defines an open cross-sectional shape to provide an opening for insertion of the radiation source 112. In one embodiment, the inner surface 116 defines a closed cross-sectional shape (e.g., in at least some axial portions of the non-imaging reflector 114). In such an embodiment, the non-imaging reflector 114 includes discrete openings to allow curing light emitted by a radiation source to enter the cavity 118.

[0040] The non-imaging reflector 114 is described as including openings 120 and 122 at its ends to allow the glass fiber 104 to enter and exit therefrom. Openings 120 and 122 are depicted as having a cross-sectional area corresponding to the cross-sectional area of ​​the cavity 118 (e.g., in the XY plane). In an embodiment, the curing apparatus includes a cap (not shown) covering portions of openings 120 and 122 to prevent curing light emitted by the radiation source 112 from exiting the cavity 118. The cap may include sub-openings having a smaller cross-sectional area than the cavity 118 to allow the glass fiber 104 to enter and exit the curing apparatus 110. In an embodiment, the cap may include an inner reflective surface facing the cavity 118 to redirect the curing light toward the glass fiber 104. It should be noted that while the curing apparatus 110 is depicted as including a single non-imaging reflector 114, the curing apparatus 110 may include multiple non-imaging reflectors placed end-to-end to form the cavity 118. Furthermore, in an embodiment, radiation source 112 may include multiple radiation sources (e.g., multiple LED arrays may be used and placed side by side).

[0041] In some embodiments, the cavity 118 comprises a uniform cross-sectional shape throughout the curing apparatus 110 (e.g., the cavity 118 may comprise the same cross-sectional area along the entire length of the non-imaging reflector 114 in the Z direction). In embodiments, the length of the cavity 118 in the Z direction corresponds to the length of the radiation source 112. The radiation source 112 may be composed of multiple LED units stacked on top of each other. In embodiments, each LED unit is 1 mm long in the Z direction, and the radiation source 112 comprises multiple such LED units such that the radiation source 112 has a length greater than or equal to 1 cm and less than or equal to 30 cm in the Z direction. Therefore, in embodiments, the length of the cavity 118 in the Z direction may be greater than or equal to 1 cm and less than or equal to 30 cm. Although Figure 1 A single non-imaging reflector 114 and radiation source 112 are depicted, but embodiments may include multiple combinations of non-imaging reflectors 114 / radiation sources 112 stacked in the Z direction (e.g., one, two, three, four, five, six, seven, eight, nine, ten, etc.), such that the curing device 110 has a total length greater than or equal to 50 cm, or greater than or equal to 75 cm, or greater than or equal to 100 cm, or greater than or equal to 125 cm, or greater than or equal to 150 cm in the Z direction. In one embodiment, the curing device 110 includes a length greater than or equal to 50 cm and less than or equal to 300 cm. In another embodiment, the curing device 110 includes a length greater than or equal to 75 cm and less than or equal to 225 cm. In yet another embodiment, the curing device 110 includes a length greater than or equal to 100 cm and less than or equal to 200 cm. In an embodiment, the length and cross-sectional area of ​​the cavity 118 of the non-imaging reflector 114 can be selected based on a combination of factors, including but not limited to the size (e.g., diameter) of the glass fiber 104, the curable coating composition 108, and the characteristics of the radiation source 112 (e.g., output power, output spectral range, spatial energy distribution of the radiation source 112, etc.).

[0042] Radiation source 112 is a light source configured to emit curing light in a spectral band of interest, which is absorbed by a component of the curable coating composition 108 (e.g., a photoinitiator) to induce its curing. In the depicted embodiment, radiation source 112 is disposed outside cavity 118 and outside non-imaging reflector 114. The spectral band of interest for radiation source 112 may depend on the components of curable coating composition 108. In an example where the curable coating composition includes TPO as a photoinitiator, radiation source 112 may emit curing light within a spectral band containing the peak absorption wavelength of the photoinitiator (e.g., greater than or equal to 345 nm and less than or equal to 410 nm, or about 395 nm). In an embodiment, radiation source 112 emits curing light that at least partially overlaps with a portion of the absorption spectrum of the photoinitiator. In an embodiment, curable coating composition 108 includes a component that absorbs UV radiation. Therefore, radiation source 112 emits curing light within the UV spectrum (e.g., greater than or equal to 200 nm and less than or equal to 450 nm). In one embodiment, the radiation source 112 includes a plurality of LEDs. In another embodiment, the LEDs are flat emitters bundled into an array to provide a light source with sufficient power for curing. In yet another embodiment, the array is flat and formed as a portion of a wafer.

[0043] exist Figure 1 In the embodiment depicted, a radiation source 112 comprises a plurality of LEDs arranged in a grid on a planar wafer. The radiation source 112 includes an emitter window (not shown) such that curing light generated by the plurality of LEDs is emitted into a cavity 118 defined by the inner surface 116 of a non-imaging reflector 114. Depending on the implementation, multiple different arrays of LEDs with different sizes, LEDs, and configurations may be used. In an embodiment, the emitter window of the radiation source 112 has a first dimension (e.g., length) greater than or equal to 10 mm (e.g., 100 mm, 150 mm, 225 mm, 300 mm, 350 mm) in the drawing direction (e.g., the Z direction) and a second dimension (e.g., width) smaller than the first dimension (e.g., 20 mm) in a second direction perpendicular to the drawing direction (e.g., the X direction). Each LED of the radiation source 112 can emit curing light. In an embodiment, each LED of the radiation source 112 emits curing light within the same spectral band of interest (e.g., overlapping with the absorption spectrum of the curable coating composition 108). In one embodiment, a subset of the LEDs of radiation source 112 emits curing light covering different spectral ranges (e.g., portions of the spectral range of interest).

[0044] The rate at which the curable coating composition 108 cures within the non-imaging reflector 114 depends on the radiant flux incident on the glass fiber 104 when it is positioned within the non-imaging reflector 114. That is, to maintain a relatively high drawing speed of 20 m / s or greater (e.g., 35 m / s or greater), the curing light from the radiation source 112 is focused such that the entire circumference of the glass fiber 104 is exposed to an energy density sufficient to cure the curable coating composition 108 as it travels through the non-imaging reflector 114 at each axial position.

[0045] In an embodiment, the radiation source 112 has a wavelength greater than or equal to 10 W / cm at the wavelength absorbed by the curable coating composition 108. 2 The irradiance. For example, in an embodiment, the curable coating composition 108 comprises a TPO photoinitiator that absorbs relatively strongly in a wavelength range greater than or equal to 345 nm and less than or equal to 410 nm (where the absorption peak is at about 385 nm). In such an embodiment, the plurality of LEDs of the radiation source 112 can have an irradiance greater than or equal to 12 W / cm² in this wavelength range. 2 The irradiance. For example, radiation source 112 can have 16 W / cm² at 385 nm. 2 Or 20W / cm 2 The irradiance. In an embodiment, the radiation source 112 can have an irradiance greater than or equal to 4 W / cm² across the entire wavelength range. 2 And less than or equal to 50W / cm 2 Irradiance.

[0046] To improve curing efficiency, the curing light emitted by the radiation source 112 can be focused to increase the energy incident on the curable coating composition 108 disposed on the glass optical fiber 104. Conventional methods for focusing the curing light include using imaging optics, where the glass optical fiber 104 is positioned at the focal point of the imaging optics (e.g., an imaging reflector). Disadvantages of this imaging optics-based method include low coupling efficiency and high sensitivity relative to the imaging optics in positioning the glass optical fiber 104. If an LED array is used as the radiation source 112, positioning the glass optical fiber 104 relative to the imaging optics becomes even more difficult because the LED array is not a point source, making it difficult to focus the emitted curing light to a single location. In some examples employing imaging optics, a power of approximately 200 W / cm² is required. 2 The LED brightness is such that it produces less than 30 W / cm² at the curable coating composition 108 disposed on the glass optical fiber 104. 2The LED brightness is low. This inefficiency can lead to incompatibility between various radiation sources and the desired drawing speed of the glass fiber 104. Furthermore, even if the glass fiber 104 is positioned at the focal point of the imaging optics, the two-dimensional nature of the LED array can cause an asymmetric intensity distribution due to the azimuth angle within the cavity 118, resulting in uneven curing around the circumference of the glass fiber 104.

[0047] In view of the shortcomings of the aforementioned imaging optics, the curing apparatus 110 includes a non-imaging reflector 114. The non-imaging reflector 114 includes an inner surface 116. The inner surface 116 reflects the curing light emitted by the radiation source 112. For example, in one embodiment, the inner surface 116 includes a reflective coating suitable for reflecting light across the entire spectral range of interest. In another embodiment, the entire non-imaging reflector 114 is constructed of a material that reflects the curing light without to which a reflective coating is applied. In another embodiment, the non-imaging reflector 114 is constructed of an aluminum-based material that has been surface-polished with Al2O3. In yet another embodiment, the inner surface 116 is coated with a filter layer that filters specific wavelengths from the curing light (e.g., a dichroic filter layer, etc.).

[0048] The inner surface includes portions facing the cavity 118 at different angular orientations, as described in this paper. Figure 2A and Figure 2B As described above. In an embodiment, multiple portions of the inner surface extend along different curvature profiles. At least some portions of the inner surface 116 have different degrees of curvature from each other. For example, in an embodiment, the cross-section of the inner surface 116 (e.g., in the XY plane) includes a first portion following a first curvature profile, a second portion following a second curvature profile, and a third portion following a third curvature profile. The first curvature profile may have a smaller degree of curvature (e.g., a larger radius of curvature) than the second and third curvature profiles, forming the largest angular portion of the inner surface 116, and is aligned with the central axis 124 of the radiation source 112 (e.g., in the Y direction). That is, the curing light originating from the central axis 124 of the radiation source 112 can be incident on the first curvature profile without redirecting it. In an embodiment, the non-imaging reflector 114 includes a uniform cross-section throughout the entire length of the non-imaging reflector, such that each of the first, second, and third portions extends through the entire length of the non-imaging reflector 114. In an embodiment, at least one of the first, second, and third portions does not extend through the entire length of the non-imaging reflector 114. The curing light from radiation source 112 can be reflected from each of the first, second, and third sections to be focused in the area where the glass fiber 104 is disposed. Details regarding the form of the first, second, and third sections are provided in this document. Figure 2A and Figure 2B Provide more details.

[0049] Now for reference Figure 2A This document depicts a top view of a portion of the curing apparatus 200. In embodiments, the curing apparatus 200 can be used in place of the description herein. Figure 1 The curing apparatus 110 is described. A glass optical fiber 290 coated with a curable coating composition 292 is disposed within the curing apparatus 200. For example, the glass optical fiber 290 can be similar to those described herein. Figure 1 The furnace 102 and coating apparatus 106 are used for production. The curing apparatus 200 includes a radiation source 202 and a non-imaging reflector 204. The radiation source 202 is an LED array comprising a plurality of LEDs 206 disposed on a wafer. In an embodiment, each of the plurality of LEDs 206 is configured to emit curing light within a spectral band, which is absorbed by the curable coating composition 292 to initiate a curing reaction therein. For example, in an embodiment, the plurality of LEDs 206 emit UV curing light with a wavelength range greater than or equal to 300 nm and less than or equal to 430 nm (e.g., greater than or equal to 360 nm and less than or equal to 430 nm). The radiation source 202 further includes an emitter window 208 that transmits curing light from the plurality of LEDs 206 into a cavity 216 defined by the inner surface 214 of the non-imaging reflector 204.

[0050] In an embodiment, the emitter window 208 of the radiation source 202 has a first dimension (e.g., length) greater than or equal to 100 mm (e.g., 150 mm, 225 mm, 300 mm, 350 mm) in a first direction, and a second dimension (e.g., width) smaller than the first dimension (e.g., 20 mm) in a second direction perpendicular to the drawing direction (e.g., the X direction). The non-imaging reflector 204 may include a length greater than or equal to 100 cm and less than or equal to 200 cm in the Z direction.

[0051] Still referencing Figure 2AThe radiation source 202 includes a frame 210 through which it is attached to the non-imaging reflector 204 at the attachment surface 212. In the depicted embodiment, the emitter window 208 is flush with the attachment surface 212 such that the emitter window 208 is separated from the center of the glass fiber 290 by a distance D in a third direction (e.g., the Y direction) perpendicular to the first and second directions. In one embodiment, the distance D is less than or equal to 76.2 mm (3 inches). In another embodiment, the distance D is greater than or equal to 25.4 mm (1.0 inch) and less than or equal to 40.64 mm (1.6 inches). In yet another embodiment, the distance D is greater than or equal to 30.48 mm (1.2 inches) and less than or equal to 38.63 mm (1.45 inches) (e.g., 35.56 mm (1.40 inches)). The distance D can be selected based on the geometry of the inner surface 214 and the characteristics of the cured light emitted by the radiation source 202. In one embodiment, the radiation source 202 is maintained in a spaced-out relationship with the non-imaging reflector 204, such that the emitter window 208 does not contact the non-imaging reflector 204. It should also be noted that in other embodiments, the radiation source 202 may be disposed within the cavity 216 of the non-imaging reflector 204.

[0052] Radiation source 202 includes an illumination axis 220 extending into cavity 216. In the illustrated embodiment, illumination axis 220 extends perpendicular to glass fiber 290. In this embodiment, illumination axis 220 corresponds to the central axis of emitter window 208 (e.g., illumination axis 220 may be centered with respect to the distribution of radiation emitted by radiation source 202). Figure 2A As depicted, illumination axis 220 extends through the center of glass fiber 290. That is, glass fiber 290 is positioned within cavity 216 such that illumination axis 220 extends through glass fiber 290. It should be understood that alternative configurations of radiation source 202 are contemplated and are within the scope of this disclosure. For example, in an embodiment, radiation source 202 may be tilted about non-imaging reflector 204 such that illumination axis 220 extends at an angle to the Y direction. Furthermore, in an embodiment, glass fiber 290 is not positioned on illumination axis 220. In an embodiment, radiation source 202 is non-planar and may include multiple illumination axes for LEDs extending in different directions.

[0053] Radiation source 202 emits curing light through emitter window 208 into cavity 216. In an embodiment, the curing light diffuses from illumination axis 220 due to its distance from emitter window 208, such that only a small portion of the curing light is incident on the curable coating composition 292 and is not reflected from non-imaging reflector 204. In an embodiment, non-imaging reflector 204 does not include a single focal point or create an image of radiation source 202. Instead, non-imaging reflector 204 is designed based on the distribution of curing light emitted by radiation source 202 and focuses the curing light within the region of cavity 216 containing glass fiber 290 (e.g., curing region 228).

[0054] The inner surface 214 of the non-imaging reflector 204 includes a first portion 222, a second portion 224, and a third portion 226. The first portion 222, the second portion 224, and the third portion 226 each extend segmentally around the inner surface 214 at different angles. In an embodiment, the inner surface 214 transitions directly from the first portion 222 to the second portion 224 and the third portion 226 at the end of the first portion 222. In an embodiment, at least two of the first portion 222, the second portion 224, and the third portion 226 include different degrees of curvature. For example, in an embodiment, the first portion 222 includes a smaller degree of curvature than the second portion 224 and the third portion 226. In an embodiment, the second portion 224 and the third portion 226 include the same degree of curvature. Figure 2A In the embodiment depicted, the first portion 222 extends segmentally around the inner surface 214 at a larger angle than the second portions 224 and the third portion 226. The first portion 222 overlaps with the illumination axis 220 of the radiation source 202. The degree of curvature of each of the first, second, and third portions 226 is designed based on the direction of the curing light emitted by the radiation source 202, such that the light is redirected to the curing region 228, which overlaps with the positioning of the glass fiber 290. In this embodiment, the glass fiber 290 is completely contained within the curing region 228, such that the curable coating composition 292 receives a substantially uniform flux to promote uniform curing around the circumference of the glass fiber 290.

[0055] Now for reference Figure 2BAccording to an example embodiment, the inner surface 214 of the non-imaging reflector 204 is depicted schematically in more detail. In the depicted embodiment, a first portion 222 of the inner surface 214 occupies a first arc length (e.g., an angular segment) associated with a first central angle 230 of a first circle 236 having a first radius 234. That is, the first portion 222 follows a first curved profile on the first circle 236. The first circle 236 includes a first center 238 located within a cavity 216. The first portion 222 extends about the arc length of the first circle 236 corresponding to the first central angle 230. Therefore, the first portion 222 has a radius of curvature corresponding to the first radius 234. In the embodiment, the first radius 234 is greater than or equal to 25.4 mm (1 inch) and less than or equal to 63.5 mm (2.5 inches) (e.g., greater than or equal to 25.4 mm (1 inch) and less than or equal to 40.64 mm (1.6 inches)). In the embodiment, the central angle 230 is greater than or equal to 100 degrees. In this embodiment, the central angle 230 is greater than or equal to 120 degrees and less than or equal to 150 degrees.

[0056] The non-imaging reflector 204 includes a central axis 270. In the depicted embodiment, the inner surface 214 is symmetrical about the central axis 270, and a first portion 222 of the inner surface 214 is centered relative to the central axis 270. That is, the central axis 270 extends in the Y direction and divides the first circle 236 into two semicircles, each half of the first portion 222 extending in the X direction on either side of the central axis 270. The central axis 270 divides the first portion 222 into two halves that are mirror images of each other on the central axis 270. The central axis 270 is the axis of symmetry of the first portion 222. Thus, the central angle 230 may include a first corner portion 232 on a first side of the central axis 270, which has the same size and shape as a second corner portion on a second side of the central axis 270. Thus, the first corner portion 232 may correspond to half of the central angle 230. Furthermore, in such an embodiment where the inner surface 214 is symmetrical about the central axis 270, the second portion 224 of the inner surface 214 has the same shape as the third portion 226 of the inner surface 214. In this embodiment, the non-imaging reflector 204 is not symmetrical about the central axis 270 (i.e., the first portion of the non-imaging reflector 204 on the first side of the central axis 270 is not a mirror image of the second portion of the non-imaging reflector 204 on the second side of the central axis 270). Such an asymmetrical embodiment can advantageously focus curing light from a radiation source having an asymmetrical energy distribution onto either side of the central axis 270 (e.g., at a position where the radiation source is at an angle relative to the central axis 270).

[0057] In the depicted embodiment, a second portion 224 of the inner surface 214 occupies a second arc length (e.g., an angular segment) associated with a second central angle 240 of a second circle 246 having a second radius 248. That is, the second portion 224 follows a second curved profile on the second circle 246. The second circle 246 has a second center 242 positioned within the cavity 216. The second portion 224 extends about the arc length of the second circle 246 corresponding to the second central angle 240. Therefore, the second portion 224 includes a radius of curvature corresponding to the second radius 248. In an embodiment, the second radius 248 is greater than or equal to 12.7 mm (0.5 inches) and less than or equal to 38.1 mm (1.5 inches) (e.g., greater than or equal to 12.7 mm (0.5 inches) and less than or equal to 22.86 mm (0.9 inches)). In an embodiment, the central angle 240 is greater than or equal to 50 degrees. In an embodiment, the central angle 240 is greater than or equal to 58 degrees and less than or equal to 118 degrees. In this embodiment, the central angle 240 is greater than or equal to 60 degrees and less than or equal to 100 degrees (e.g., 88 degrees).

[0058] In an embodiment, the third portion 226 of the inner surface 214 may have a similar geometry to the second portion 224 to maintain symmetry about the central axis 270. Thus, the third portion 226 of the inner surface 214 occupies a third arc length (e.g., an angular segment) associated with the third central angle 250 of the third circle 252, which has a third radius 256 equal to the second radius 248 of the second circle 246. That is, the third portion 226 follows a third curved profile on the third circle 252. The third circle 252 includes a third center 254 positioned within the cavity 216. The third portion 226 extends about the arc length of the third circle 252 corresponding to the third central angle 250. Therefore, the third portion 226 includes a radius of curvature corresponding to the third radius 256. In one embodiment, the third radius 256 is greater than or equal to 12.7 mm (0.5 inches) and less than or equal to 38.1 mm (1.5 inches) (e.g., greater than or equal to 12.7 mm (0.5 inches) and less than or equal to 22.86 mm (0.9 inches)). In one embodiment, the central angle 250 is greater than or equal to 50 degrees. In one embodiment, the central angle 250 is greater than or equal to 58 degrees and less than or equal to 118 degrees. In one embodiment, the central angle 250 is greater than or equal to 60 degrees and less than or equal to 100 degrees (e.g., 88 degrees).

[0059] The first circle 236 includes a first center 238, the second circle 246 includes a second center 242, and the third circle 252 includes a third center 254 (e.g., located at the first, second, and third center positions, respectively). Assuming that each of the first portion 222, the second portion 224, and the third portion 226 extends along a circular profile (i.e., the first, second, and third curved profiles, respectively), the first portion 222, the second portion 224, and the third portion 226 can focus light incident perpendicularly thereon toward the first center 238, the second center 242, and the third center 254. However, according to the non-imaging optical design of the inner surface 214, none of the first centers 238, the second center 242, and the third center 254 coincide with each other. That is, each of the first centers 238, the second center 242, and the third center 254 is displaced relative to each other within the cavity 216. In the depicted embodiment, the second center 252 and the third center 254 are both offset from the first center 238 by a distance 271 in a direction perpendicular to the central axis 270 (e.g., the Y direction). Additionally, the glass fiber 290 (see...) Figure 2A It is positioned at fiber position 272, which is also displaced from each of the first center 238, the second center 242 and the third center 254.

[0060] Fiber optic position 272 (e.g., the center of glass fiber 290 is located within the non-imaging reflector 204) is positioned on central axis 270. A first center 238 of the first circle 236 is also positioned on central axis 270, but is axially displaced from fiber optic position 272 on central axis 270 (e.g., in the Y direction). A second center 248 and a third center 254 are each offset from central axis 270 by a distance 264 in a direction perpendicular to central axis 270 (e.g., in the X direction). Furthermore, the second center 248 and the third center 254 are aligned in a direction perpendicular to central axis 270 and offset from the first center 238 by a distance 260 in a direction parallel to central axis 270.

[0061] In this embodiment, the fiber position 272 is based on the measured intensity distribution of the solidified light within the cavity 216. In this embodiment, the fiber position 272 corresponds to the use of a light source 202 (see...). Figure 2AThe maximum intensity of the cured light is measured by a detector. In an embodiment, fiber position 272 corresponds to the maximum intensity of the cured light measured using a detector facing away from radiation source 202 (e.g., facing the first portion 222). In an embodiment, fiber position 272 corresponds to a position within cavity 216 where the azimuth variation of the measured intensity of the cured light is less than a threshold. The azimuth variation of the measured intensity of the cured light can indicate the difference between the intensity or power measured using different azimuth orientations of the detector within cavity 216. Each azimuth orientation of the detector can indicate the rotation angle of the detector's axis relative to the X-axis in the XY plane. For example, in an embodiment, the measured azimuth variation of the cured light, inversely related to the measurement direction, is less than or equal to 40% (e.g., less than or equal to 35.5%).

[0062] Still referencing Figure 2B The inner surface 214 is depicted as including an extension 274 extending in a direction parallel to the central axis 270. The extension 274 defines the boundary of an opening 276 in the non-imaging reflector 204. The opening 276 includes a width 262 in a direction perpendicular to the central axis 270. The extension 274 is spaced a distance 266 from the central axis 270. In an embodiment, the distance 266 is half the width 262 of the opening 276. A first center 238 is located at a distance 258 from the end of the extension 274. In an embodiment, the distance 258 is determined based on the length of the extension 274, which may house the radiation source 202 (see...). Figure 2A The distance between fiber optic position 272 and the first center 238. This distance can be set to maximize the flux at fiber optic position 272.

[0063] In this embodiment, the size of the opening 276 is based on the size of the radiation source 202 (see [reference]). Figure 2A For example, the size of opening 276 can be based on the emitter window of radiation source 202 (e.g., as described herein regarding...). Figure 2A The size of the emitter window 208 described. In an embodiment, the extension 274 can be inserted into the frame 210 of the radiation source 202 such that the emitter window 208 is disposed in the opening 276 between the extensions 274. Such a structure is advantageous because the cavity 216 is sealed by the emitter window 208 to prevent reflected curing light from leaving the cavity 216. Some embodiments may not include the extension 274 (e.g., the radiation source 202 may be spaced apart from the non-imaging reflector 204, or flush with the ends of the second portion 224 and the third portion 226). In an embodiment, the radiation source 202 is coaxial with the non-imaging reflector 204 such that the illumination axis 220 (see Figure 2AThe radiation source 202 extends (e.g., overlaps) with the central axis 270. In such an embodiment, the radiation source 202 is centered relative to the non-imaging reflector 204, such that substantially equal portions of the solidified light emitted by the radiation source 202 are redirected by the second portion 224 and the third portion 226.

[0064] It should be understood that alternative structures for the inner surface 214 are conceived and are within the scope of this disclosure. For example, the angular range of each portion of the inner surface 214 (e.g., the first central angle 230, the second central angle 240, and the third central angle 250) may depend on the distance between the radiation source 202 and the non-imaging reflector 204 (e.g., regarding the distance between the radiation source 202 and the non-imaging reflector 204). Figure 2A The distance D described. Additionally, aspects of each portion of the inner surface 214 (e.g., the values ​​of the first central angle 230, the second central angle 240, and the third central angle 250; the values ​​of the first radius 234, the second radius 248, and the third radius 256; the positioning of the first center 238, the second center 242, and the third center 254) can vary based on the distribution of the curing light emitted from the radiation source 202. Furthermore, the non-imaging reflector 204 is not limited to three portions, but may include two or more portions in embodiments.

[0065] In an embodiment, at least one of the first portion 222, the second portion 224, and the third portion 226 does not follow a circular profile. For example, at least one of the first portion 222, the second portion 224, and the third portion 226 may follow an elliptical profile, and the positioning of the first center 238, the second center 242, and the third center 254 described herein may correspond to the positioning of the focal point of the elliptical profile. In another example, at least one of the first portion 222, the second portion 224, and the third portion 226 may follow a curved profile that follows a conical, parabolic, or other non-circular shape. Any non-imaging reflector comprising multiple portions with different degrees of curvature, consistent with this disclosure, may be used.

[0066] An embodiment where the non-imaging reflector 204 is asymmetrical relative to the central axis 270 is also envisioned. In such an embodiment, the angular range of the second portion 224 may differ from that of the third portion 226, and the first portion 222 may not be centered relative to the central axis 270. Additionally, the first center 238, the second center 242, and the third center 254 may be positioned differently (e.g., in such an embodiment, the second center 242 and the third center 254 may not be aligned in the X direction and may be set at different distances from the central axis 270). Embodiments where the second portion 224 does not have the same degree of curvature as the third portion 226 are also envisioned. That is, regarding... Figure 2A and Figure 2B The examples described are merely illustrative and are not intended to be limiting. Use of this article regarding... Figures 2A-2B The described structure is used to construct an example curing device. A commercially available LED array is used as a radiation source 202 and is positioned such that its emitter window 208 is approximately 27.94 mm (1.1 inches) away from the fiber optic location 272 at a distance D. In this example, a first portion 222 extends along a curved profile along a first circle 236 corresponding to a central angle 230 of 143 degrees. The first circle 236 includes a radius of 28.96 mm (1.14 inches). Second portions 224 and third portions 226 extend along curved profiles along second circles 246 and third circles 252 corresponding to central angles 240 and 250 of approximately 88 degrees. The second source 246 and third circle 252 include a radius of curvature of 17.78 mm (0.70 inches). An opening 276 includes a width 262 of 31.5 mm (1.24 inches). The distance to 264 is 10.41 mm (.41 inches), the distance to 258 is 16.51 mm (0.65 inches), and the distance to 260 is 3.56 mm (.14 inches).

[0067] Measurements were performed to compare the performance of the non-imaging reflector 204 with that of a comparison reflector. Figure 3A Two curves were plotted to measure the experimental curing degree of the acrylate glass fiber coating, which varies with the power supplied to the radiation source. Curve 302 depicts the results for the comparative reflector, while curve 304 depicts the results for the non-imaging reflector 204. Curve 304 shifts upward from curve 302, reflecting an increase in curing degree varying with UV metering greater than 0.10% (e.g., an increase in curing degree of the non-imaging reflector 204 varying with UV dose of approximately 0.15% compared to the comparative reflector). Such results indicate that the non-imaging reflector described herein can contribute to improving the processing efficiency of existing reflectors.

[0068] Now for reference Figure 3B The azimuth energy distribution of the non-imaging reflector 204 according to this example was measured and compared with the azimuth energy distribution of an elliptical comparator. (Reference) Figure 2B A photodetector is positioned at fiber location 272. The photodetector has a finite field of view, allowing curing light within a finite angular window to enter the photodetector during each measurement. The photodetector integrates the amount of curing light incident upon it during the measurement period to measure the power of the incident curing light. The photodetector is positioned around a central axis (e.g., along...). Figure 2BThe photodetector (extending in the Z direction) is rotated by a fixed angular amount to generate multiple angular measurements. That is, the power of the curing light received by the photodetector, varying with the rotation angle, is measured, with measurements taken for rotation angles from 0 degrees to 360 degrees. A similar procedure is followed to measure the azimuth energy distribution of a comparison reflector (e.g., the photodetector is positioned at the focal point of the comparison reflector) and the same LED source.

[0069] Figure 3B A first azimuth energy distribution 306 and a second azimuth energy distribution 308 of the non-imaging reflector 204 are depicted according to this example. The first azimuth energy distribution 306 depicts the angular measurement of the comparative reflector. The first azimuth energy distribution 306 and the second azimuth energy distribution 308 depict normalized power measurements that vary depending on the angular position. The magnitude of the normalized power measurement is depicted at a distance from the center 310 of the graph. Compared to the first azimuth energy distribution 306 of the comparative reflector, the second azimuth energy distribution 308 reflects a consistently higher measured power of the non-imaging reflector 204. For azimuth angles greater than or equal to 90 degrees and less than or equal to 270 degrees (e.g., representing areas where the glass fiber is not facing the radiation source), the normalized power measurement of the first azimuth energy distribution 306 is consistently less than 0.5. Within a similar angular range, the second azimuth energy distribution is consistently greater than 0.8. Additionally, for azimuth angles less than or equal to 90 degrees and greater than or equal to 270 degrees (e.g., representing the region of the glass fiber facing the radiation source), the non-imaging reflector 204 provides power similar to that of the comparison reflector. Thus, the non-imaging reflector 204 significantly improves curing performance within an angular range greater than or equal to 90 degrees and less than or equal to 270 degrees, while maintaining performance at other azimuth angles, resulting in greater curing uniformity.

[0070] It is noteworthy that, at the same measurement angle, the second azimuth energy distribution 308 includes a power measurement that is consistently higher than that of the first azimuth energy distribution 306. As a result, the curable coating composition within the non-imaging reflector 204 is exposed to a greater curing luminous flux than when positioned within the comparison reflector. Additionally, the first azimuth energy distribution 306 (e.g., at approximately 30 degrees) contains a maximum measured power that is only about 65% of the maximum measured power of the second azimuth energy distribution 308 (e.g., at approximately 180 degrees). The second azimuth energy distribution 308 also advantageously has a smaller degree of variation than the first azimuth energy distribution 306. The normalized power measurements of the first azimuth energy distribution 306 differ from each other by up to 50%, while the normalized power measurements of the second azimuth energy distribution 308 differ from each other by up to 35%. Therefore, the non-imaging optical reflector 204 consistently provides a larger and more uniform curing luminous flux than the comparison reflector.

[0071] Figure 4 The benefits of such an azimuth energy density distribution are demonstrated by a graph depicting multiple measurements of the curing variation of an acrylate fiber coating dependent on azimuth. Each measurement depicts the maximum value of multiple angular measurements of the degree of curing (e.g., at azimuth positions of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively) minus the minimum value of multiple angular measurements. Figure 4 The distribution includes a first distribution 402 representing the distribution of curing variation measurements associated with a comparative reflector. A second distribution 404 represents the distribution of curing variation measurements associated with not using an optical reflector. A third distribution 406 represents the distribution of curing variation measurements associated with the non-imaging reflector 204 described herein. As depicted in the first and second distributions 402 and 404, the comparative reflector provides a similar range of curing variation as without a reflector. That is, the comparative reflector does not significantly improve curing uniformity dependent on azimuth angle compared to not using a reflector. The first distribution 402 depicts a curing variation approaching 3.0% or more. In contrast, the third distribution 406 provides a curing variation approaching at most 1.0%. This closer distribution of curing variation is what this document refers to. Figure 3B The results describe the uniform azimuth energy distribution of the curing light from the non-imaging reflector 204.

[0072] Figure 5 The image depicts light 502 emitted by radiation source 202 and reflected within non-imaging reflector 204. (As shown...) Figure 5 As shown, light 502 is reflected into curing region 228, such that the maximum intensity of the curing light is within curing region 228. As described above, the positioning of curing region 228 overlaps with the positioning of glass fiber 290. Therefore, glass fiber 290 receives light 502 of substantially uniform concentration, thereby providing substantially uniform curing of the coating on glass fiber 290.

[0073] In some embodiments, the maximum intensity of the curing light is less than 3.0 mm from the center of the glass fiber 290. In other embodiments, the maximum intensity of the curing light is about 2.5 mm or less, or about 2.0 mm or less, or about 1.5 mm or less, or about 1.0 mm or less, or about 0.5 mm or less, or about 0.0 mm from the center of the glass fiber 290.

[0074] Table 1 below shows the curing light (emitted by radiation source 202) relative to... Figure 2BThe table shows the intensity at the center of the glass fiber 290 of the exemplary non-imaging reflector 204. As shown in Table 1, in this example, the center of the glass fiber 290 at the (0.0 mm, 0.0 mm) location is also at the same location as the maximum intensity of the curing light (at the 100% curing light intensity mark). Further note that at the (0.0 mm, 0.0 mm) location, moving upwards or downwards in the y-direction or moving away from the center of the glass fiber 290 in the x-direction results in a decrease in the intensity of the curing light. For example, the intensity of the curing light is only 85% of the maximum intensity at the (0.0 mm, -2.5 mm) location. Further outward movement in both the x and y directions results in the intensity of the curing light decreasing to 76% of the maximum intensity at the (4 mm, -5.0 mm) location. The relative displacement values ​​in Table 1 are derived with the radiation source 202 positioned to the left of the glass fiber 290.

[0075] Table 1: Percentage of maximum intensity of curing light relative to fiber position

[0076]

[0077] In the example in Table 1, the first portion 222, the second portion 224, and the third portion 226 are each configured to reflect curing light (emitted by radiation source 202) such that the curing light is "focused" onto the curing region 228. "Focused" means that the light intensity is 60% or greater relative to the maximum intensity. Therefore, all reflected curing light within the curing region 228 has approximately 60% or greater relative to the maximum intensity of the curing light. In other embodiments, all reflected curing light within the curing region 228 has approximately 65% ​​or greater, or approximately 70% or greater, or approximately 75% or greater, or approximately 80% or greater, or approximately 85% or greater, or approximately 90% or greater, or approximately 95% or greater, or approximately 100% relative to the maximum intensity of the curing light.

[0078] like Figure 5 As shown in Table 1, the location of the maximum intensity of the curing light and the location of the glass fiber 290 are positioned very close to each other and within the curing region 228. In some embodiments, the location of the maximum intensity of the curing light and the location of the glass fiber 290 overlap (partially or completely). Figure 6A and Figure 6B This further demonstrates the maximum intensity of the cured light and Figure 2B The relative displacement between the positions of the glass optical fiber 290 in the exemplary embodiment of the comparator reflector.

[0079] exist Figure 6A and Figure 6B In this process, an LED array light source is used to provide the intensity distribution of the curing light. Figure 6A A first calculated intensity distribution 602 associated with the elliptical comparator was depicted. As described above, Figure 6B Depicting and Figure 2B A second calculated intensity distribution 604 is associated with the non-imaging reflector 204. The first calculated intensity distribution 602 includes a peak intensity region 606 offset from the fiber position 608 of the comparator reflector. Conversely, the second calculated intensity distribution 604 includes a peak intensity region 610 encompassing the fiber position 612. Positioning the fiber position 612 within the peak intensity region 610 advantageously results in the coating composition disposed therein receiving additional cured light flux from the reflection of the non-imaging reflector 204 compared to the comparator reflector. According to the first calculated intensity distribution 602, the curable coating composition disposed at the fiber position 608 absorbs a total flux of 2.66 mW of cured light from the LED array. Conversely, the curable coating composition disposed at the fiber position 612 absorbs a total flux of 4.24 mW, representing an increase of more than 50% compared to the comparator reflector. This greater flux absorption facilitates greater drawing speeds in fiber production and coating processes, thereby enhancing the overall fiber production efficiency of existing processes.

[0080] Based on the above description, it should be understood that incorporating a non-imaging reflector into a curing apparatus for curing coating compositions on glass optical fibers can result in improved curing performance in terms of the total absorption flux and azimuth distribution of the coating composition. Incorporating multiple sections into a non-imaging reflector with varying degrees of curvature (each section reflecting curing light from a radiation source) advantageously focuses the curing light onto a curing region containing the glass optical fiber. This curing region contains a curing light flux with a variation of less than 35% dependent on the azimuth angle within the non-imaging reflector, thereby providing uniform curing around the entire circumference of the glass optical fiber. The multiple sections of the non-imaging reflector can follow a circular profile with centers offset from each other and be positioned to provide a greater curing light flux to the glass optical fiber than existing reflectors, thus resulting in improved curing performance.

[0081] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Therefore, it is intended that the specification cover a variety of modifications and variations to the embodiments described herein, provided that such modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. An apparatus for curing a coating composition disposed on a glass optical fiber, the apparatus comprising: A reflector having a longitudinal length and defining a cavity, the reflector comprising: An inner surface, defining the boundary of the cavity, the inner surface comprising: The first part extends along a first curved profile to reflect curing light, the first curved profile forming a first circle, the first circle including a first radius and a first center located at a first center position within the cavity; The second portion extends along a second curved profile to reflect curing light, the second curved profile forming a second circle, the second circle including a second radius and a second center located at a second center position within the cavity; and The third part extends along a third curved profile to reflect the curing light, the third curved profile forming a third circle, the third circle including a third radius and a third center located at a third center position within the cavity. Wherein, the first center position is different from the second center position, the third center position is different from the first center position, and the second center position is different from the third center position. The optical fiber position of the glass optical fiber is shifted from the first center position, the second center position, and the third center position.

2. The apparatus of claim 1, further comprising: The radiation source includes an array of light-emitting diodes (LEDs).

3. The apparatus as described in claim 2, characterized in that, The first center position is set to be closer to the radiation source in a first direction perpendicular to the longitudinal length of the reflector than the second center position and the third center position.

4. The apparatus as described in claim 3, characterized in that, The second center position and the third center position are axially aligned in a second direction perpendicular to the first direction.

5. The apparatus as described in any one of claims 1 to 3, characterized in that, The second radius and the third radius are each smaller than the first radius.

6. The apparatus according to any one of claims 1 to 3, characterized in that, The first portion of the inner surface includes a first arc length corresponding to the central angle of the first circle, the first arc length being greater than or equal to 120 degrees and less than or equal to 150 degrees.

7. The apparatus as claimed in claim 6, characterized in that: The second portion and the third portion of the inner surface respectively include a second arc length and a third arc length corresponding to the central angles of the second circle and the third circle; The second arc length is greater than or equal to 60 degrees and less than or equal to 100 degrees; and The third arc length is greater than or equal to 60 degrees and less than or equal to 100 degrees.

8. The apparatus of any one of claims 1 to 3, further comprising: The glass optical fiber is positioned at the location of the optical fiber.

9. The apparatus as claimed in claim 8, characterized in that, The glass optical fiber is positioned at a location different from the first center position, the second center position, and the third center position.

10. A method for curing a coating composition on a glass optical fiber, the method comprising: Guide the glass optical fiber into In the cavity of the reflector of the device according to claim 1, the glass optical fiber has a coating composition disposed thereon, and Curing light is guided from a radiation source to a curing zone within the cavity, such that the curing light is reflected from the first, second, and third portions and focused into the curing zone, such that all reflected curing light within the curing zone has an intensity of 60% or greater relative to the maximum intensity of the reflected curing light, and the glass optical fiber is disposed in the curing zone.

11. The method as described in claim 10, characterized in that, The glass optical fiber is guided through the opening at a speed of 35 m / s or greater.

12. The method as described in claim 10, characterized in that, The curing light includes wavelengths greater than or equal to 200 nm and less than or equal to 450 nm.

13. The method according to any one of claims 10-12, characterized in that, The curing light is reflected from the first, second, and third portions and focused onto the curing zone, such that all the reflected curing light within the curing zone has an intensity of 80% or greater relative to the maximum intensity of the reflected curing light.

Images