Composite elliptical reflector for hardening optical fibers

Abstract

hardening device, comprising: a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector are arranged such that they have a common focal point, and a light source positioned at a second focal point of the first elliptical cylindrical reflector, wherein light emitted by the light source is reflected from the first elliptical cylindrical reflector to the common focal point and is reflected back from the second elliptical cylindrical reflector to the common focal point, wherein a light source is absent at a second focal point of the second elliptical cylindrical reflector.

Description

Background and Summary

[0001] Optical fibers are ubiquitously used in lighting and imaging applications, as well as in the telecommunications industry, where they offer higher data transmission rates over long distances compared to electrical cabling. Optical fibers are also more flexible, lighter, and can be drawn to thinner diameters than metal wires, allowing for more efficient bundling of fibers into cables. Surface coatings applied using an ultraviolet (UV) curing process are used to protect optical fibers from physical damage and moisture ingress, as well as to maintain their long-term durability during operation.

[0002] Carter et al. (US Patent No. 6,626,561 B2) addresses the problems of UV curing uniformity for optical fibers with surfaces located off-center of a UV curing device that uses an elliptical reflector to direct UV light from a single UV light source positioned at a second focal point of the elliptical reflector onto the surface of the optical fiber. Curing uniformity problems can occur due to inaccurate alignment of the optical fiber relative to the light source or an irregularly shaped optical fiber.To address these problems, Carter uses a UV lamp structure that utilizes an elliptical reflector to irradiate areas of optical fiber positioned near a second focal point of the elliptical reflector with UV light from a single light source positioned near a first focal point of the elliptical reflector, with both the optical fiber and the bulb slightly offset from the focal points. This way, the UV light rays reaching the surface of the optical fiber are scattered, and the irradiation and curing of the optical coating can potentially be more uniform.

[0003] US 2013 / 0 068 969 A1 discloses an apparatus for UV curing a coating or printing ink on a workpiece, such as an optical fiber, comprising two elliptical reflectors arranged to have a common focal point. The workpiece is centered at the common focal point, so that the two elliptical reflectors are arranged on opposite sides of the workpiece. Two separate light sources are positioned at a second focal point of each elliptical reflector, with the light emitted by the light sources being substantially concentrated onto the surface of the workpiece at the common focal point.

[0004] US 2010 / 0 084 574 A1 discloses a UV radiation curing system for treating a substrate, such as a fiber optic cable or a silicone tube. The system comprises a processing chamber that allows the transport of a continuous piece of the substrate to be treated. As the substrate moves through the processing chamber, the substrate surface is treated with ultraviolet radiation from a plasma lamp activated by a microwave generator. The system includes two elliptical reflectors of different sizes, allowing larger-diameter substrates to be efficiently treated with ultraviolet radiation.

[0005] JP H05-229885 A discloses a housing for a lamp chamber, a cylindrical mercury lamp, a housing for a working chamber, a light-transmitting tube, and a converging mirror unit. These are arranged to form a device for curing a coating agent. An elliptical converging mirror on the lamp side is machined to form part of a first elliptical cylindrical surface having an axial line of the lamp as the first focal point and an optical fiber path as the second focal point. An elliptical converging mirror on the working side is machined to form a second elliptical cylindrical surface having the axial line of the lamp as the first focal point and the fiber path as the second focal point. The minor axis of the ellipse of the first cylindrical surface is then made larger than that of the second cylindrical surface.The optical fiber is irradiated with reflected light, which propagates from the converging mirror toward the optical fiber to heat a coating agent applied to the optical fiber.

[0006] The present inventor has recognized a potential problem with the above approach. By moving the UV light source and optical fiber away from the focal points of the elliptical reflector, the intensity of the UV light irradiating the optical fiber surfaces is scattered and reduced, thereby reducing curing and production rates and resulting in higher manufacturing costs.

[0007] The features known from the prior art are achieved by a curing device having the features of claim 1, by a photoreactive system having the features of claim 11, and by a method having the features of claim 14. Advantageous embodiments of the invention are the subject of the dependent claims.

[0008] One approach to addressing the aforementioned problems includes a curing device comprising: a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector are arranged to have a common focal point, and a light source positioned at a second focal point of the first elliptical cylindrical reflector, wherein light emitted by the light source is reflected by the first elliptical cylindrical reflector toward the common focal point and reflected back by the second elliptical cylindrical reflector toward the common focal point. It is provided that a light source is absent at a second focal point of the second elliptical cylindrical reflector.In another embodiment, a method of hardening a workpiece comprises drawing the workpiece along a common focal point of a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, emitting UV light from a light source positioned at a second focal point of the first elliptical cylindrical reflector, reflecting the emitted UV light from the first elliptical cylindrical reflector onto a surface of the workpiece, and reflecting the emitted UV light from the second elliptical cylindrical reflector further toward the surface of the workpiece.In another embodiment, a method comprises positioning a workpiece along a first inner axis of a reflector, the reflector comprising first curved surfaces having a first curvature and second curved surfaces having a second curvature, positioning a light source along a second inner axis of the reflector, and emitting light from the light source, the emitted light being reflected from the first curved surfaces and the second curved surfaces onto the workpiece.

[0009] It should be understood that the foregoing summary is provided to introduce, in a simplified form, a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is determined solely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that resolve any disadvantages noted above or in any part of this disclosure. Short description of the drawings Fig. Figure 1 shows an example of a photoreactive system that includes a power source, a controller, and a light-emitting subsystem. Fig. Figure 2 shows a cross-section of an elliptical cylindrical reflector for a single light source UV curing device. Fig. Figure 3 shows a cross-section of an example of two elliptical surfaces arranged with a common focus. Fig. Figure 4 shows a cross-section of an exemplary configuration of dual elliptical reflectors arranged with a common focus. Fig. Figure 5 shows a cross-section of an exemplary curing apparatus including dual elliptical reflectors and a light source located at a second focal point of one of the elliptical reflectors. Fig. 6 shows a cross-section of an exemplary curing apparatus including dual elliptical reflectors and a light source located at a second focal point of one of the elliptical reflectors. Fig. Figure 7 shows a cross-section of an exemplary photoreactive system. Fig. Figure 8 shows a perspective cross-section of an exemplary photoreactive system. Fig. Figure 9 shows a perspective view of a dual elliptical reflector for a photoreactive system. Fig. 10 shows a final cross-section of the dual elliptical reflector of Fig. 9. Fig. 11 shows a flow diagram of an exemplary method for hardening a workpiece such as an optical fiber, for example, using the hardening apparatus as shown in Fig. 5 is used. Detailed description

[0010] This description relates to a UV curing apparatus, method, and system for use in the manufacture of coated optical fibers, ribbons, cables, and other workpieces. Optical fiber coatings can be UV-cured using a UV curing apparatus that utilizes dual elliptical reflectors designed with a common focal point, with the workpiece (e.g., the optical fiber) positioned at the common focal point and two UV light sources located at the second focal point of each elliptical reflector. Fig. Figure 1 shows an example of a photoreactive system that includes a power source, a controller, and a light-emitting subsystem. Fig. Figure 2 shows a coupling optics configuration of a conventional UV curing device with a single elliptical reflector. Fig. Figure 3 shows an example of two elliptical surfaces arranged with a common focus. Fig. 4-6 show coupling optics configurations with dual elliptical reflectors for a UV curing device, where the dual elliptical reflectors have a common focal point. Fig. 7-8 are cross-sectional and perspective views of an exemplary UV curing device including dual elliptical reflectors designed with a common focus. Fig. 9-10 include perspective and cross-sectional views of an exemplary dual elliptical reflector. Fig. 11 is a flowchart showing steps of an exemplary method for UV curing an optical fiber or other workpiece.

[0011] With reference now to Fig. 1 shows a block diagram for an exemplary configuration of a photoreactive system, such as a curing device 10. In one example, the curing device 10 may include a light-emitting subsystem 12, a controller 14, a power source 16, and a cooling subsystem 18. The light-emitting subsystem 12 may include a plurality of semiconductor devices 19. The plurality of semiconductor devices 19 may be an array 20 of light-emitting elements, such as, for example, a linear array of LED devices. The array 20 of light-emitting elements may also include, for example, a two-dimensional array of LED devices or an array of LED devices. Semiconductor devices may provide a radiant output 24. The radiant output 24 may be directed toward a workpiece 26 located at a fixed plane from the curing device 10. Returned radiation 28 may be emitted from the workpiece 26 (e.g.,by reflection of the radiant power 24) back to the light-emitting subsystem 12.

[0012] The radiant power 24 may be directed to the workpiece 26 by means of coupling optics 30. The coupling optics 30 may be implemented in various ways when used. For example, the coupling optics may comprise one or more layers, materials, or other structures interposed between the semiconductor devices 19 and a window 64, providing radiant power 24 to surfaces of the workpiece 26. For example, the coupling optics 30 may comprise a microlens array to collect, focus, collimate, or otherwise improve the quality or effective size of the radiant power 24. As another example, the coupling optics 30 may comprise a microreflector array. When utilizing such a microreflector array, each semiconductor device providing radiant power 24 may be arranged in a respective microreflector on a one-to-one basis.As another example, an array of semiconductor devices 20 providing radiant power 24 may be arranged in macroreflectors on a many-to-one basis. In this way, a coupling optic 30 may include both microreflector arrays, where each semiconductor device is arranged on a one-to-one basis in a respective microreflector, and macroreflectors, where the magnitude and / or quality of the radiant power 24 from the semiconductor devices is further enhanced by macroreflectors. For example, macroreflectors may include elliptical cylindrical reflectors, parabolic reflectors, dual elliptical cylindrical reflectors, and the like.

[0013] Each of the layers, materials, or other structures of the coupling optics 30 can have a selected refractive index. By properly selecting each refractive index, reflection at interfaces between layers, materials, and other structures in the path of the radiant power 24 (and / or the returned radiation 28) can be selectively controlled. For example, by controlling differences in these refractive indices at a selected interface, e.g., window 64 disposed between the semiconductor devices and the workpiece 26, reflection at that interface can be decreased or increased to enhance the transmission of radiant power at that interface for eventual delivery to the workpiece 26.For example, the coupling optics may comprise a dichroic reflector, whereby certain wavelengths of incident light are absorbed while others are reflected and focused to the surface of the workpiece 26.

[0014] The coupling optics 30 can be used for various purposes. Example purposes include, alone or in combination, protecting the semiconductor devices 19, retaining cooling fluid associated with the cooling subsystem 18, collecting, condensing, and / or collimating the radiant power 24, collecting, directing, or rejecting returned radiation 28, or for other purposes. As another example, the curing apparatus 10 can utilize the coupling optics 30 to improve the effective quality, uniformity, or magnitude of the radiant power 24, particularly as it is delivered to the workpiece 26.

[0015] Selected ones of the plurality of semiconductor devices 19 may be coupled to the controller 14 via coupling electronics 22 to provide data to the controller 14. As described further below, the controller 14 may also be implemented to control these data-providing semiconductor devices, e.g., via the coupling electronics 22. The controller 14 may be connected to the power source 16 and the cooling subsystem 18 and may be implemented to control them. For example, the controller may provide a larger drive current to light-emitting elements distributed in the central portion of the array 20 and a smaller drive current to light-emitting elements distributed in the end portions of the array 20 to increase the usable area of ​​light emitted onto the workpiece 26. In addition, the controller 14 may receive data from the power source 16 and the cooling subsystem 18.In one example, the irradiation at one or more locations on the surface of the workpiece 26 may be detected by sensors and communicated to the controller 14 in a control scheme. In another example, the controller 14 may be connected to a controller of another lighting system (in . Fig. 1 not shown) to coordinate the control of both lighting systems. For example, controllers 14 of multiple lighting systems may operate in a cascading master-slave control algorithm, with the setpoint of one of the controllers being determined by the output of the other controller. Other control strategies for operating the curing apparatus 10 in conjunction with another lighting system may also be used. As another example, controllers 14 for multiple lighting systems arranged side by side may control lighting systems in an identical manner to increase the uniformity of emitted light across multiple lighting systems.

[0016] In addition to the power source 16, the cooling subsystem 18, and the light-emitting subsystem 12, the controller 14 may also be connected to and implemented to control an internal element 32 and an external element 34. The internal element 32 may be internal to the curing apparatus 10, as shown, while the external element 34 may be external to the curing apparatus 10, as shown, but may be associated with the workpiece 26 (e.g., handling, cooling, or other external equipment) or otherwise associated with a photoreaction (e.g., curing) that the curing apparatus 10 supports.

[0017] The data obtained by controller 14 from one or more of power source 16, cooling subsystem 18, light-emitting subsystem 12, and / or elements 32 and 34 may be of various types. For example, the data may be representative of one or more properties associated with coupled semiconductor devices 19. As another example, the data may be representative of one or more properties associated with the respective light-emitting subsystem 12, power source 16, cooling subsystem 18, internal element 32, and external element 34 providing the data. As yet another example, the data may be representative of one or more properties associated with workpiece 26 (e.g., representative of the radiant power energy or spectral component(s) directed toward the workpiece). Furthermore, the data may be representative of a combination of these properties.

[0018] The controller 14, upon receiving such data, may be implemented to respond to this data. For example, the controller 14 may be implemented in response to such data from such a component to control one or more of the power source 16, the cooling subsystem 18, the light-emitting subsystem 12 (including one or more such coupled semiconductor devices), and / or the elements 32 and 34. For example, in response to data from the light-emitting subsystem indicating that the light energy at one or more points associated with the workpiece is insufficient, the controller 14 may be implemented to either (a) increase the power supply from the power source to one or more of the semiconductor devices, (b) increase the cooling of the light-emitting subsystem 18 (e.g.,certain light-emitting devices provide greater radiant power when cooled), (c) increasing the time during which current is supplied to those devices, or (d) a combination of the above.

[0019] Individual semiconductor devices 19 (e.g., LED devices) of the light-emitting subsystem 12 can be independently controlled by the controller 14. For example, the controller 14 can control a first group of one or more individual LED devices to emit light of a first intensity, wavelength, and the like, while controlling a second group of one or more individual LED devices to emit light of a different intensity, wavelength, and the like. The first group of one or more individual LED devices can be located within the same array 20 of semiconductor devices or can come from more than one array of semiconductor devices 20 from multiple lighting systems 10. The array 20 of semiconductor devices can also be independently controlled by the controller 14 from other arrays of semiconductor devices in other lighting systems.For example, the semiconductor devices of a first array may be controlled to emit light of a first intensity, wavelength, and the like, while those of a second array in a different curing device may be controlled to emit light of a second intensity, wavelength, and the like.

[0020] As another example, under a first set of conditions (e.g., for a particular workpiece, photoreaction, and / or operating conditions), the controller 14 may operate the curing device 10 to implement a first control strategy, whereas under a second set of conditions (e.g., for a particular workpiece, photoreaction, and / or operating conditions), the controller 14 may operate the curing device 10 to implement a second control strategy. As described above, the first control strategy may involve operating a first group of one or more individual semiconductor devices (e.g.,LED devices) to emit light of a first intensity, wavelength, and the like, while the second control strategy may include operating a second group of one or more individual LED devices to emit light of a second intensity, wavelength, and the like. The first group of LED devices may be the same group of LED devices as the second group and may span one or more arrays of LED devices, or may be a different group of LED devices than the second group, but the different group of LED devices may include a subset of one or more LED devices from the second group.

[0021] The cooling subsystem 18 may be implemented to control the thermal behavior of the light-emitting subsystem 12. For example, the cooling subsystem 18 may provide for cooling the light-emitting subsystem 12 and, in particular, the semiconductor devices 19. The cooling subsystem 18 may also be implemented to cool the workpiece 26 and / or the space between the workpiece 26 and the curing device 10 (e.g., the light-emitting subsystem 12). For example, the cooling subsystem 18 may include an air or other fluid cooling system (e.g., water). The cooling subsystem 18 may also include cooling elements, such as cooling fins, attached to the semiconductor devices 19 or the array 20 thereof or to the coupling optics 30. For example, the cooling subsystem may include blowing cooling air over the coupling optics 30, wherein the coupling optics 30 is equipped with external fins to improve heat transfer.

[0022] The curing apparatus 10 can be used for various applications. Examples include, without limitation, curing applications ranging from color printing to DVD manufacturing and lithography. The applications in which the curing apparatus 10 can be utilized can have associated operating parameters. That is, an application can have associated operating parameters as follows: Providing one or more radiant power values ​​at one or more wavelengths applied for one or more time periods. To properly achieve the photoresponse associated with the application, optical power can be applied at or near the workpiece 26 at or above one or more predetermined values ​​of one or more of these parameters (and / or for a particular time, times, or time ranges).

[0023] To follow the parameters of a planned application, the semiconductor devices 19 that provide radiant power 24 can be operated according to various properties associated with the application parameters, e.g., temperature, spectral distribution, and radiant power. At the same time, the semiconductor devices 19 can have certain operating specifications that can be associated with the manufacture of the semiconductor devices and can be followed, among other things, to preclude destruction of the devices and / or prevent degradation of the devices. Other components of the curing device 10 can also have associated operating specifications. These specifications can include, among other parameter specifications, ranges (e.g., maximum and minimum ranges) for operating temperatures and applied electrical power.

[0024] Accordingly, the curing device 10 can support monitoring of application parameters. Furthermore, the curing device 10 can provide for monitoring semiconductor devices 19, including their respective properties and specifications. Furthermore, the curing device 10 can also provide for monitoring selected other components of the curing device 10, including their properties and specifications.

[0025] Providing such monitoring may enable testing for proper system operation so that the operation of the curing device 10 may be reliably assessed. For example, the curing device 10 may be operating improperly with respect to one or more of the application parameters (e.g., temperature, spectral distribution, radiant power, and the like), the properties of a component associated with such parameters, and / or the respective operating specifications of a component. Providing monitoring may be responsive to and executed in accordance with data received by the controller 14 from one or more of the system components.

[0026] Monitoring may also support the control of system operation. For example, a control strategy may be implemented by means of the controller 14, wherein the controller 14 receives and responds to data from one or more system components. This control strategy described above may be implemented directly (e.g., by controlling a component through control signals directed to the component based on data that considers the operation of that component) or indirectly (e.g., by controlling the operation of a component through control signals designed to adjust the operation of other components).For example, a radiant power of a semiconductor device may be adjusted indirectly by control signals sent to the power source 16, which adjusts the power supplied to the light-emitting subsystem 12, and / or by control signals sent to the cooling subsystem 18, which adjusts the cooling applied to the light-emitting subsystem 12.

[0027] Control strategies can be used to enable and / or enhance proper system operation and / or application performance. In a more specific example, control can also be used to enable and / or enhance a balance between the array's radiant power and its operating temperature, for example, to prevent the semiconductor devices 19 from heating beyond their specifications while also delivering sufficient radiant energy to the workpiece 26 to, for example, execute a photoreaction of the application.

[0028] In some applications, a high radiant power may be delivered to the workpiece 26. Accordingly, the light-emitting subsystem 12 may be implemented using an array of semiconductor light-emitting devices 20. For example, the light-emitting subsystem 12 may be implemented using a high-density light-emitting diode (LED) array. Although LED arrays may be used and are described in more detail herein, it should be understood that the semiconductor devices 19 and their arrays 20 may be implemented using other light-emitting technologies without departing from the principles of the invention; examples of other light-emitting technologies include, without limitation, organic LEDs, laser diodes, and other semiconductor lasers.

[0029] Continue with Fig. 1, the plurality of semiconductor devices 19 may be in the form of arrays 20 or an array of arrays (e.g. as in Fig. 1). The arrays 20 may be implemented such that one or more or most of the semiconductor devices 19 are configured to provide radiant power. At the same time, however, one or more of the semiconductor devices 19 of the array are implemented to provide monitoring of selected characteristics of the array. The monitoring devices 36 may be selected from among the devices in the array and may, for example, have the same construction as the other emitting devices. The difference between emitting and monitoring may, for example, be determined by the coupling electronics 22 associated with the particular semiconductor device (in a basic form, an LED array may include monitoring LED devices, where the coupling electronics provide a return current, and emitting LED devices, where the coupling electronics provide a forward current).

[0030] Further, based on the coupling electronics, selected ones of the semiconductor devices in the array may be either / or both / and multi-function devices and / or multi-mode devices, where (a) multi-function devices could detect more than one property (e.g., radiant power, temperature, magnetic fields, vibration, pressure, acceleration, and other mechanical forces or deformations) and can be switched among these detection functions according to the application parameters or other governing factors, and (b) multi-mode devices could be capable of emission, detection, and another mode (e.g., off) and can be switched among these modes according to the application parameters or other governing factors.

[0031] As described above, the curing device 10 can be configured to receive a workpiece 26. For example, the workpiece 26 can be a UV-curable optical fiber, ribbon, or cable. Furthermore, the workpiece 26 can be positioned at or near the focal points of the coupling optics 30 of the curing device 10. In this way, UV light emitted by the curing device 10 can be directed to the surface of the workpiece via coupling optics for UV curing and driving the photoreactions. Furthermore, the coupling optics 30 of the curing device 10 can be configured with a common focal point, as described in more detail below.

[0032] With reference now to Fig. 2 shows an example of a single elliptical reflector 200. Single elliptical coupling optics are used in conventional UV curing devices for curing coatings on optical fiber workpieces.

[0033] An ellipse is a plane curve resulting from the intersection of a cone with a plane in such a way as to produce a closed curve and is defined as the locus of all points in the plane whose distances to two fixed points (the foci of the ellipse) add up to the same constant. The distance between antipodes on the ellipse or pairs of points centered at the center of the ellipse is maximum along its major axis or transverse diameter and minimum along its perpendicular minor axis or conjugate diameter. An ellipse is symmetric about its major and minor axes. The foci of an ellipse are two particular points on the major axis of the ellipse and are equidistant from the center of the ellipse (where the major and minor axes intersect). The sum of the distances from any point on the ellipse to these two foci is constant and equal to the major axis.Each of these two points is called the focus of the ellipse. An elliptical cylinder is a cylinder with an elliptical cross-section.

[0034] The elliptical reflector 200 comprises an elliptical cylinder with an elliptical cross-section. An elliptical reflector 200 thus has two focal points, wherein light emitted from one focal point along the axial length of the elliptical cylinder is concentrated at the second focal point along the axial length of the cylinder. The elliptical reflector surface 210 is an example of a light control device with an elliptical cylindrical shape and elliptical cross-section, such that light rays 250 originating from a single light source 230 at a first focal point (e.g., a focal point along an axis of the elliptical cylinder) of the elliptical reflector are directed to a second focal point 240 (e.g., a focal point along a second axis of the elliptical cylinder).For UV curing, the inner surface of the elliptical reflector may be UV-reflective to substantially direct UV light to the surface of a workpiece located at the second focal point 240.

[0035] In single elliptical reflector devices with a single light source, the near-field workpiece surfaces (e.g., the workpiece surfaces facing the light source) can receive light at higher intensities than the far-field workpiece surfaces (e.g., the workpiece surfaces facing away from the light source). Thus, single elliptical reflectors can also include a cylindrical auxiliary rear reflector 260 to assist in concentrating UV light rays 264 originating from the light source 230 and directed onto the far-field surface of the workpiece. The use of auxiliary rear reflectors can be utilized to provide more uniform irradiation of a workpiece.

[0036] As described above, a conventional elliptical single reflector 200 has two focal points, wherein light emanating from a light source 230 at a first focal point can be substantially concentrated at a second focal point 240.

[0037] With reference now to Fig. 3 shows an example of two elliptical surfaces 310 and 320 that are superimposed and joined, forming a union of two elliptical sub-surfaces. The ends where the two elliptical sub-surfaces are joined form two edges 314 and 324 near the centers of the otherwise curved elliptical arcs. As shown in Fig. 3, the elliptical surfaces 310 and 320 may be aligned about their major axes 352 and 350 and arranged to substantially share a common focal point 330. Furthermore, the major axes 352 and 350 of the elliptical surfaces 320 and 310 each have an equal length, and minor axes 356 and 358 of the elliptical surfaces 310 and 310 are each of the same length. The elliptical surfaces 310 and 320 may be arranged on opposite sides of the workpiece at or near the substantially common focal point 330. Furthermore, a light source may be positioned at or near one of the two focal points 340 and 346 on opposite sides of the workpiece or positioned surrounding it. The light source may be, for example, a single LED device comprising an array of LEDs or an array of LED arrays.In this arrangement, the dual elliptical surfaces can substantially focus light emitted from the light source positioned at or near one of the focal points 340 and 346 of the dual elliptical reflectors onto the surfaces of the workpiece.

[0038] In this way, reflecting emitted light from dual elliptical reflectors changes surfaces of the workpiece that are far-field relative to the light source to near-field relative to the second elliptical reflector (e.g., the reflector without the light source at the second non-common focal point). Thus, the dual elliptical reflector design can potentially avoid the use of back reflectors, simplifying the design and cost of the system. In this way, the Fig. 3, the configuration shown as an example, relative to the UV curing device with an elliptical single reflector, can also potentially achieve higher radiation intensity and more uniform radiation intensity across the workpiece surfaces. Achieving a higher and more uniform radiation intensity can potentially enable increased production rates and / or shorter curing times, thereby reducing product manufacturing costs.

[0039] Another potential advantage of dual elliptical reflectors relative to single elliptical reflectors is that UV light can be concentrated more evenly across all surfaces of the workpiece while maintaining high intensity compared to single elliptical UV curing devices. Because dual elliptical reflectors are utilized, light emitted by the light sources can still be substantially directed toward the surface of the workpiece, even if there is a slight misalignment of the workpiece from the common focal point or a slight misalignment of one or more light sources from one of the focal points.In cases where the cross-section of the workpiece may be irregularly shaped or asymmetric, or in cases where the workpiece cross-section may be large, light emitted by the light sources can still be substantially directed to the surface of the workpiece when dual elliptical reflectors are used.

[0040] The elliptical surfaces 310 and 320 may be substantially elliptical or at least partially elliptical, with the dual reflectors forming substantially elliptical cylinders, and with light radiated or directed near the focal points 340 and 346 being reflected on the inner surfaces of the surfaces 310 and 320 substantially at the common focal point 330. For example, the shapes of the surfaces 310 and 320 may deviate somewhat from perfectly elliptical without significantly compromising the convergence of light radiated from a light source near or at either of the focal points 340 and 346 at the common focal point 330. As another example, shapes of surfaces 310 and 320 that deviate slightly from perfectly elliptical may include faceted elliptical surfaces, where the general shape of the reflectors may be elliptical, but individual portions are faceted to deviate from an ellipse.Faceted or partially faceted elliptical surfaces can potentially enable control of reflected light to improve light uniformity or intensity at the workpiece surface for a particular light source. For example, the facets can be flat or curved, uniform or continuous, to approximate an elliptical shape, and can deviate slightly from an elliptical shape to account for the emission shape of the light source, thereby improving irradiance at a workpiece surface. Each of the facets can be flat, with corners connecting several of the flat facets to form the elliptical surface. Alternatively, the facets can have a curved surface.

[0041] With reference now to Fig. 4 shows a cross-section of an exemplary coupling optics for a UV curing device 400, which includes dual elliptical reflectors 480 and 490 aligned about their major axes and arranged to share a common focal point 460, as in the arrangement of the two elliptical surfaces 310 and 320 of Fig. 3. The elliptical reflector 490 may comprise a partially elliptical reflector having an opening 430 opposite the common focal point 460, wherein the opening 430 is symmetrical about a major axis of the elliptical reflector 490. The opening 430 may assist in mounting, positioning, and / or aligning, as well as integrating the dual elliptical reflectors 480 and 490 with other components of the UV curing device 400, such as a light source 420. Edges 432 of the opening 430 are positioned such that the opening 430 is no wider than an axis 436 parallel to the minor axis of the elliptical reflector 490 at the second focal point. A light source 420 may be positioned near or substantially at the second focal point of the elliptical reflector 490. Furthermore, a sample tube 470 is positioned so that its central axis is substantially centered around the common focal point.

[0042] In this manner, the elliptical reflectors 480 and 490 form two partially elliptical cylinders that are joined at edges 486 and 488 where the elliptical reflectors 480 and 490 meet. The UV curing device 400 may be further configured to receive a workpiece 450, wherein the workpiece 450 may enter the sample tube 470 such that its axis extends along the axis of the common focal point 460. In this configuration, with the dual elliptical reflectors disposed on opposite sides of the workpiece, the dual elliptical reflectors may substantially converge and direct light beams 420 and 428 emitted by the light sources 420 onto the workpiece surfaces in a substantially uniform manner and with high intensity.Irradiating the workpiece in a substantially uniform manner herein may comprise irradiating all workpiece surfaces included in the UV curing device with substantially the same irradiance (e.g., power per unit area). For example, for a workpiece comprising an optical fiber, positioning the light source 420 substantially at the second focal point of the elliptical reflector 490 may facilitate irradiating the workpiece within a threshold distance surrounding the fiber with a beam of constant irradiance. For example, the threshold distance may comprise a constant beam surrounding the fiber of 1 mm. As another example, the threshold distance may comprise a constant beam surrounding the fiber of 3 mm.

[0043] Furthermore, because the dual elliptical reflectors are positioned on opposite sides of the workpiece, the surfaces of the workpiece that are near-field and far-field relative to the light source are far-field and near-field, respectively, relative to the second elliptical reflector (e.g., the elliptical reflector without a light source at its non-common focal point). Thus, far-field surfaces of the workpiece can be uniformly irradiated relative to the light source or the second elliptical reflector, precluding the use of back reflectors or reflective surfaces other than the inner surfaces of the dual elliptical reflectors to direct the light onto the workpieces. In cases where the workpiece enters a sample tube 470, the size of the sample tube may further limit how small the elliptical reflectors can be made, as the walls of the sample tube 470 engage the reflector walls.Reducing the size of the elliptical reflectors can help position the light source closer to the workpiece. A dual elliptical reflector design overcomes this limitation by allowing each elliptical reflector to have a smaller minor or major axis, allowing the light source to be positioned closer to the workpiece.

[0044] The dual elliptical reflectors 480 and 490 may include a reflective inner surface 484 and 494 for directing light rays 428 and 424 originating from the light source 420. As shown, light emitted by the light source 420 may include light rays 424 reflected by the reflective inner surface 494 of the elliptical reflector 490 onto the workpiece surfaces and light rays 428 reflected by the reflective inner surface 484 of the elliptical reflector 480 onto the workpiece surfaces. Light emitted by the light source 420 may further include light rays reflected by both reflective inner surfaces 484 and 494 of the elliptical reflectors 480 and 490 onto the workpiece surfaces, respectively, and light rays 426 reflected by the light source 420 directly onto the workpiece surfaces.Light rays 428 reflected by the elliptical reflector 480 may pass through the second focal point 482 of the elliptical reflector 480 before being reflected by the elliptical reflector 480 onto the workpiece surfaces.

[0045] The reflective inner surfaces 484 and 494 can reflect rays of visible and / or UV and / or IR light with minimal absorption or refraction of the light. Alternatively, the reflective inner surfaces 484 and 494 can be dichroic, allowing a specific range of light wavelengths to be reflected, whereas light of wavelengths outside a specific range can be absorbed at the reflective inner surfaces 484 and 494. For example, the reflective inner surfaces 484 and 494 can be configured to reflect rays of UV and visible light but absorb rays of IR light. Such a reflective inner surface can be potentially useful for heat-sensitive coatings or workpieces, or for influencing the rate and uniformity of the curing reaction at the surface of the workpiece 450.The reflective inner surfaces 484 and 494, on the other hand, may preferentially reflect both UV and IR, since curing reactions can proceed more quickly at higher temperatures.

[0046] The workpiece 450 may include optical fibers, ribbons, or cables with a range of sizes and dimensions. The workpiece 450 may also include a UV-curable cladding and / or surface coating, as well as UV-curable ink printed onto its surface. A UV-curable cladding may include one or more UV-curable polymer systems and may also include more than one UV-curable layer, which may be UV-curable in one or more curing stages. UV-curable surface coatings may include a thin film or ink curable at the surface of the optical fiber or optical fiber cladding. For example, the workpiece may be an optical fiber comprising a core and a cladding layer, and the cladding may include a coating comprising a UV-curable polymer, such as a polyimide or acrylate polymer, or one or more other UV-curable polymers.As another example, a dual-layer coating can be used, in which the workpiece can be coated with an inner layer, which, when cured, can have a soft and rubbery quality to minimize attenuation due to microbending, and an outer layer that can be stiffer and suitable for protecting the workpiece (e.g., the optical fiber) from abrasion and environmental exposure (e.g., moisture, UV). The inner and outer layers can comprise a polymer system, for example, an epoxy system, with initiators, monomers, oligomers, and other additives.

[0047] During curing, the workpiece 450 may be pulled in the axial direction within the sample tube 470 through the UV curing device, with the workpiece 450 substantially axially centered around the common focal point 460. Furthermore, the sample tube 470 may be axially centered around the common focal point 460 and may concentrically surround the workpiece 450. The sample tube 470 may be made of glass or quartz or another optically and / or UV and / or IR transparent material and may not be too thick, so that the sample tube 470 does not block or significantly interfere with the light rays emitted by the light source 42, including light rays reflected from the inner surface of the dual elliptical reflectors 480 and 490 through the sample tube onto the surfaces of the workpiece 450. Dual elliptical reflectors 480 and 490 may also be referred to as compound elliptical reflectors. The sample tube 470 can be used as in Fig. 4, or the sample tube 470 may have another suitably shaped cross-section. The sample tube 470 may also contain an inert gas such as nitrogen, carbon dioxide, helium, and the like to maintain an inert atmosphere around the workpiece and reduce oxygen inhibition, which can slow the UV curing reaction.

[0048] The light source 420 may comprise one or more semiconductor devices or arrays of semiconductor devices, such as LED light sources, LED array light sources, or microwave-powered or halogen arc light sources or arrays thereof. Furthermore, the light source 420 located substantially at the focal point 492 may extend along the axial length of the focal point 492 such that it extends along the length of the partially elliptical cylindrical reflector 490 of the UV curing device 400. The light source 420, particularly arrays of light sources or arrays of arrays of light sources, may further encompass or extend beyond the focal point 492 along or at points along the length of the partially elliptical cylindrical reflector 490 of the UV curing device 400.In this way, light emitted by the light source 420 along the axial length of the dual elliptical reflectors is substantially redirected to the surface of the workpiece 450 along its entire length.

[0049] Furthermore, the light source 420 may emit one or more of visible, UV, or IR light. As another example, the light source 420 may emit UV light of a first spectrum during a first period of time and may then emit UV light of a second spectrum during a second period of time. The first and second spectra emitted by the light source 420 may, but do not have to, overlap. For example, if the first light source 420 includes a first LED array with a first type of LED light source and a second LED array with a second type of LED light source, then their emission spectra may, but do not have to, overlap. Furthermore, the intensities of light emitted by the light source 420 from the first LED array and the second LED array may be identical or different, and their intensities may be independently controlled by an operator using a controller 14 or coupling electronics 22.In this way, both the light intensity and wavelengths of the light source 420 can be flexibly and independently controlled to achieve uniform UV irradiation and UV curing of a workpiece. For example, if a workpiece is irregularly shaped and / or not symmetrical around the common focal point of the dual elliptical reflector, the UV curing device can irradiate one portion of the workpiece differently than another portion to achieve uniform curing. As another example, when applying different coatings or inks to the surface of the workpiece, the UV curing device can irradiate one portion of the workpiece differently than another portion.

[0050] In a UV curing device with dual elliptical reflectors 480 and 490 and the light source 420 positioned at a second focal point of the elliptical reflector 490, a workpiece positioned at the common focal point 460 can be illuminated more effectively than in UV curing devices as shown in Fig. 2, only one elliptical reflector can be irradiated with UV light more evenly and at higher intensities. In this way, UV curing of a workpiece using dual elliptical reflectors 480 and 490 and the light source 420 positioned at a second focal point of the elliptical reflector 490 can achieve faster cure rates and more uniform curing of the workpiece. In other words, faster cure rates can be achieved while achieving more uniform curing. In the case of a coated workpiece, non-uniformly or unevenly coated workpieces can potentially experience non-uniform forces upon expansion or contraction of the coating. In the case of an optical fiber, non-uniformly coated optical fibers can be susceptible to greater signal attenuation.Achieving more uniform curing may include, in addition to achieving concentric coatings around the workpiece (e.g., an optical fiber) that have a constant thickness and are continuous over the application length of the workpiece (e.g., an optical fiber), a higher percentage of reactive monomer and oligomer conversion and a higher degree of crosslinking in the polymer system.

[0051] Achieving faster curing rates in a continuous or batch manufacturing process for optical fibers, cables, ribbons, or the like can potentially reduce manufacturing time and costs. Furthermore, achieving more uniform curing can potentially impart greater durability and strength to the workpiece. In the case of an optical fiber coating, improved coating uniformity can potentially preserve fiber strength, thereby potentially increasing the durability of the optical fiber in preventing attenuation of signal transmission due to phenomena such as microbending deformations, stress corrosion, or other mechanical damage to the optical fiber. Higher degrees of crosslinking can also potentially improve the chemical resistance of the coating, preventing chemical penetration and chemical corrosion or damage to the optical fiber.Optical fibers can be severely degraded by surface defects. With conventional UV curing equipment, faster curing rates can be achieved, but only at the expense of reduced curing uniformity; similarly, more uniform curing can be achieved, but only at the expense of slowing curing rates.

[0052] In curing apparatus 400, dual elliptical reflectors 480 and 490 have equal major axis and minor axis dimensions. In other embodiments, an exemplary curing apparatus may include dual elliptical reflectors with different major axes. Increasing or decreasing a major axis length of the elliptical reflectors may increase or decrease a distance between a common focal point and a second focal point of the elliptical reflectors.

[0053] With reference now to Fig. 5 shows an example of a curing device 500 comprising dual elliptical reflectors 580 and 590 with a common focal point 560, whose major axes are aligned along an axis 502, wherein the major axis of the dual elliptical reflector 580 is smaller than the major axis of the dual elliptical reflector 590. The dual elliptical reflectors 580 and 590 meet at an outer upper edge 588 and lower edge 586. In this way, the elliptical reflectors 580 and 590 form two partially elliptical cylinders that are connected at edges 586 and 588 where the elliptical reflectors 580 and 590 meet. Inner and outer surfaces of the dual elliptical reflectors 580 and 590 can, as in Fig. 5, the reflectors may be faceted, where the general shape of the reflectors may be elliptical, but individual portions 512 may be faceted to deviate slightly from an ellipse. Faceted or partially faceted elliptical surfaces may potentially enable control of reflected light to improve light uniformity or light intensity at the workpiece surface for a particular light source. For example, the facets may be flat or curved, uniform or continuous, to approximate an elliptical shape, and may deviate slightly from an elliptical shape to account for the emission shape of the light source, thereby improving irradiance at a workpiece surface. Each of the facets may be flat, with corners connecting several of the flat facets to form the elliptical surface. Alternatively, the facets may have a curved surface.

[0054] A light source 520 is positioned at or near a second focal point 592 of the elliptical reflector 590, and a workpiece 550 is positioned at the common focal point 560, the workpiece being concentrically surrounded by a sample tube 570. The elliptical reflector 590 may comprise a partially elliptical reflector having an opening 530 opposite the common focal point 560, the opening 530 being symmetrical about a major axis of the elliptical reflector 590. The opening 530 may assist in mounting, positioning, and / or aligning, as well as integrating the dual elliptical reflectors 580 and 590 with other components of the curing apparatus 500, such as a light source 520. Edges 532 of the opening 530 are positioned so that the opening 530 is no wider than an axis 536 parallel to the minor axis of the elliptical reflector 590 at the second focal point.

[0055] The UV curing device 500 may be further configured to receive a workpiece 550, wherein the workpiece 550 may enter the sample tube 570 such that its axis extends along the axis of the common focal point 560. In this configuration, with the dual elliptical reflectors disposed on opposite sides of the workpiece, the dual elliptical reflectors may substantially converge and direct light beams 524 and 528 emitted from the light source 520 onto the workpiece surfaces in a substantially uniform and high-intensity manner. The dual elliptical reflectors 580 and 590 may include a reflective inner surface 584 and 594 for directing light beams 528 and 524 originating from the light source 520.As shown, light emitted by light source 520 may include light rays 524 reflected by the reflective inner surface 594 of elliptical reflector 590 onto the workpiece surfaces and light rays 528 reflected by the reflective inner surface 584 of elliptical reflector 580 onto the workpiece surfaces. Light emitted by light source 520 may further include light rays reflected by both reflective inner surfaces 584 and 594 of elliptical reflectors 580 and 590 onto the workpiece surfaces, and light rays reflected by light source 520 directly onto the workpiece surfaces. Light rays 528 reflected by elliptical reflector 580 may pass through second focal point 582 of elliptical reflector 580 before being reflected by elliptical reflector 580 onto the workpiece surfaces.

[0056] By configuring the major axis of the elliptical reflector 580 to have a major axis that is smaller than the major axis of the elliptical reflector 590, a distance from the reflective inner surface 584 to the workpiece 550 may be reduced and may be smaller than a distance from the reflective inner surface 594 to the workpiece 550. Accordingly, an intensity and uniformity of emitted light reflected by the elliptical reflector 580 onto far-field and mid-field surfaces (e.g., relative to the light source 520) of the workpiece 550 may be enhanced.

[0057] With reference now to Fig. 6 shows another example of a curing device 600. The curing device 600 includes dual elliptical reflectors 680 and 690 with a common focal point 660, whose major axes are aligned along an axis 602. Furthermore, the major axis and minor axis of the elliptical reflector 680 are the same and smaller than the minor axis of the elliptical reflector 690. Accordingly, the elliptical reflector 680 may include a circular reflector 680, wherein the circular reflector 680 is a special case of an elliptical reflector whose major and minor axes are the same and whose two focal points are coincident. Thus, the focal point (e.g., common focal points) of the circular reflector 680 is coincident with a first focal point of the elliptical reflector 690. The circular reflector 680 and the elliptical reflector 690 meet at an outer upper edge 688 and lower edge 686.In this way, the circular reflector 680 and the elliptical reflector 690 form two partial cylinders that are connected at the edges 686 and 688 where the circular reflector 680 and the elliptical reflector 690 meet. The inner and outer surfaces of the dual elliptical reflectors 680 and 690 may be formed as shown in FIG. Fig. 6, the reflectors may be faceted, where the general shape of the reflectors may be elliptical, but the individual portions 612 are faceted to deviate slightly from an ellipse. Faceted or partially faceted elliptical surfaces can potentially enable control of reflected light to improve light uniformity or light intensity at the workpiece surface for a particular light source. For example, the facets may be flat or curved, uniform or continuous, to approximate an elliptical shape, and may deviate slightly from an elliptical shape to account for the emission shape of the light source, thereby improving irradiance at a workpiece surface. Each of the facets may be flat, with corners connecting several of the flat facets to form the elliptical surface. Alternatively, the facets may have a curved surface.

[0058] A light source 620 is positioned at or near a second focal point 692 of the elliptical reflector 690, wherein a workpiece 650 may be positioned at the common focal point 660, the workpiece being concentrically surrounded by a sample tube 670. The elliptical reflector 690 may comprise a partially elliptical reflector having an opening 630 opposite the common focal point 660, wherein the opening 630 is symmetrical about a major axis of the elliptical reflector 690. The opening 630 may assist in mounting, positioning, and / or aligning, as well as integrating the circular elliptical reflector 680 and the elliptical reflector 690 with other components of the curing apparatus 600, such as a light source 620. Edges 632 of the opening 630 are positioned such that the opening 630 is no wider than an axis 636 parallel to the minor axis of the elliptical reflector 690 at the second focal point.

[0059] The UV curing device 600 may be further configured to receive a workpiece 650, wherein the workpiece 650 may enter the sample tube 670 such that its axis extends along the axis of the common focal point 660. In this configuration, with the dual elliptical reflectors disposed on opposite sides of the workpiece, the dual elliptical reflectors may substantially converge and direct light beams 624 and 628 emitted from the light source 620 onto the workpiece surfaces in a substantially uniform and high-intensity manner. The circular reflector 680 and the elliptical reflector 690 may include a reflective inner surface 684 and 694 for directing light beams 628 and 624 originating from the light source 620.As shown, light emitted by light source 620 may include light rays 624 reflected from the reflective inner surface 694 of elliptical reflector 690 onto the workpiece surfaces and light rays 628 reflected from the reflective inner surface 684 of circular reflector 680 onto the workpiece surfaces. Light emitted by light source 620 may further include light rays reflected from both reflective inner surfaces 684 and 694 of circular reflector 680 and elliptical reflector 690 onto the workpiece surfaces, and light rays reflected from light source 620 directly onto the workpiece surfaces.

[0060] When configuring the circular reflector 680 with a diameter smaller than the major axis of the elliptical reflector 690, a distance from the reflective inner surface 684 to the workpiece 650 is reduced and is smaller than a distance from the reflective inner surface 694 to the workpiece 650. Furthermore, a reflected path length or emitted light from the light source 620 by means of the reflective inner surface 684 is reduced. Furthermore, the distance from all points on the reflective inner surface 684 to the workpiece 650 is approximately the same. Accordingly, an intensity and uniformity of emitted light reflected by the circular reflector 680 on far-field and mid-field surfaces (e.g., relative to the light source 620) of the workpiece 650 can be enhanced. Furthermore, manufacturing a circular reflector can be more efficient compared to an elliptical reflector (e.g.,with unequal major and minor axes) may be less expensive due to its greater symmetry.

[0061] With reference now to Fig. 7 shows a cross-sectional view of an example photoreactive system or UV curing system 700. The UV curing system 700 is shown for illustrative purposes to include a dual elliptical cylindrical reflector 775, which, similar to the curing device 600, includes a circular cylindrical reflector 780 and an elliptical cylindrical reflector 790. The UV curing system 700 may also include dual elliptical cylindrical reflectors as shown in the curing devices 500 and 400. The circular cylindrical reflector 780 and the elliptical cylindrical reflector 790 are joined at edges 786 and 788, forming partially elliptical surfaces and having a common focal point 760.

[0062] A light source 710 may include a housing 716 and inlet and outlet pipe connections 714 through which cooling fluid may circulate. The light source 710 may include one or more arrays of UV LEDs positioned substantially along a second focal point 792 of the elliptical cylindrical reflector 790. The UV curing system 700 may further include mounting brackets 718 by which the housing 716 is attachable to a reflector assembly base plate 720. The UV curing system 700 may also include a sample tube 770 and a workpiece (not shown), for example, an optical fiber, that is drawn within the sample tube 770 and positioned substantially about the central longitudinal axis of the sample tube 770.The longitudinal axis of the sample tube 770 can be positioned substantially along a common focal point 760 of the elliptical cylindrical reflector, whereby UV light from the light source 710 can be directed by the circular cylindrical reflector 780 and the elliptical cylindrical reflector 790 substantially through the sample tube to surfaces of the workpiece. The sample tube 770 can be constructed of quartz, glass, or another material and can have a cylindrical or other geometry, whereby UV light directed onto the outer surface of the sample tube 770 can pass through the sample tube 770 without significant refraction, reflection, or absorption.

[0063] The reflector assembly base plate 720 may be connected to reflector assembly end plates 724, which may be mechanically attached to an axial end of the dual elliptical cylindrical reflector 775. The sample tube 770 may also be mechanically attached to the reflector assembly end plates 724.In this manner, mounting brackets 718, reflector assembly end plates 724, and reflector assembly base plate 720 may serve to assist in the alignment of light source 710, elliptical cylindrical reflector 775, and sample tube 770, wherein light from light source 710 is positioned substantially around a second focal point 792 of elliptical cylindrical reflector 790, wherein the sample tube is positioned substantially around a common focal point of the dual elliptical cylindrical reflector 775, and wherein UV light from light source 710 is directed by the dual elliptical cylindrical reflector 775 through sample tube 770 substantially toward surfaces of the workpiece.The reflector assembly end plate 724 may also include an alignment mechanism (not shown) whereby the orientation and / or position of the sample tube 770 may be adjusted after the reflector assembly end plates 724, the reflector assembly base plate 720, the elliptical cylindrical reflector 760, and the sample tube 770 have been assembled. The reflector assembly base plate 720 may also be connected along one side to a reflector assembly mounting plate 740. The reflector assembly mounting plate 740 may further be provided with one or more mounting slots 744 (see FIG. Fig. 8) and one or more mounting holes 748 (see Fig. 8) through which the UV curing system 700 can be attached. The UV curing system 700 may also include additional connection ports 722 and 750 for other purposes, such as connecting electrical wires, mounting sensors, and the like. Furthermore, the UV curing system 700 may include a reflector housing 712 and a cooling fan 716 attached to the reflector housing 712 for dissipating heat from the UV curing system 700.

[0064] With reference now to Fig. 8 shows a perspective cross-sectional view of the UV curing system 700 of Fig. 7, with the reflector assembly end plates 724 removed for illustration. In addition to the above Fig. 7, the UV curing system 700 further comprises an opening or recess 840 in the reflector assembly base plate 720 through which light emitted by the light source 710 is transmitted. As in Fig. As shown in Figure 8, the recess 840 may substantially span an axial length of the dual elliptical reflector 775, such that light from the light source 710 is radiated along the entire length of the dual elliptical reflector 775. In addition to the cooling fan 716 and the cooling fluid inlet and outlet tube connections 714, the reflector housing 712 may also include ribbed surfaces 820 to assist heat dissipation away from the UV curing system 700.

[0065] The UV curing system 700 from Fig. 7 and Fig. In Figure 8, the dual elliptical reflector 775 is shown having a thin, rounded sheet metal construction. In one example, the dual elliptical reflector may comprise formed thin sheets of polished aluminum, which may be cleanable, reusable, and replaceable. In another example, fins may be added to the outer surface (e.g., outward relative to the area illuminated by the light source 710) to increase the heat transfer area of ​​the dual elliptical reflector.

[0066] With reference now to Fig. 9 and Fig. 10, these perspective and end cross-sectional views show another embodiment of a dual elliptical reflector 900 with a common focus 982. The dual elliptical reflector 900 includes reflective inner surfaces 984 and 994 of a first elliptical cylindrical reflector and a second elliptical cylindrical reflector joined at edges 986 and 988. As shown, the first elliptical cylindrical reflector comprises a circular cylindrical elliptical reflector, however, the first elliptical cylindrical reflector may be any embodiment of an elliptical cylindrical reflector having a major axis and / or minor axis that is smaller than the major axis and / or minor axis of the second elliptical cylindrical reflector. The dual elliptical reflector 900 may be machined or cast metal and polished to form reflective inner surfaces 984 and 994.Alternatively, the dual elliptical reflector may be machined, molded, cast, or extruded from glass, ceramic, or plastic and treated with a high reflectance coating to form reflective interior surfaces 984 and 994. Furthermore, the dual elliptical reflector may be fabricated in two halves, 900A and 900B, and fitted and / or joined during assembly of the curing apparatus. The dual elliptical reflector 900 further includes ribbed surfaces 918 to increase the heat transfer surface area. Mounting holes 996 may be provided on a bottom surface 964 of the dual elliptical reflector 900 to facilitate attaching and positioning the dual elliptical reflector 900 to other components of a UV curing system (e.g., UV curing system 700), such as a light source or an enclosure.The dual elliptical reflector 900 further includes an opening or recess 968 along its entire axial length. The recess 968 is positioned along the major axis of the dual elliptical reflector 900 such that the recess 968 corresponds to the second focal point 992 of the second elliptical cylindrical reflector.

[0067] In this way, a curing device may comprise a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector are arranged to have a common focal point, and a light source positioned at a second focal point of the first elliptical cylindrical reflector, wherein light emitted by the light source is reflected by the first elliptical cylindrical reflector toward the common focal point and reflected back by the second elliptical cylindrical reflector toward the common focal point. Furthermore, a light source may be absent at a second focal point of the second elliptical cylindrical reflector.Furthermore, a major axis of the first elliptical cylindrical reflector may be greater than a major axis of the second elliptical cylindrical reflector, a minor axis of the first elliptical cylindrical reflector may be greater than a minor axis of the second elliptical cylindrical reflector, and the major axis of the second elliptical reflector and the minor axis of the second elliptical reflector may be the same.

[0068] The first elliptical cylindrical reflector and the second elliptical cylindrical reflector may be configured to receive a workpiece and may be disposed on opposite sides of the workpiece.The elliptical surfaces of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector may meet and be joined, forming upper and lower edges near a central position of the curing device and extending along a major axis length of the first elliptical cylindrical reflector and a major axis length of the second elliptical cylindrical reflector, wherein the elliptical surfaces of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector extend outwardly from the upper and lower edges to each side of the curing device where the elliptical cylindrical reflectors connect to housings for the at least two light sources.Furthermore, the light source may include a power source, a controller, a cooling subsystem, and a light-emitting subsystem, wherein the light-emitting subsystem includes coupling electronics, coupling optics, and a plurality of semiconductor devices, and the housing may contain the light source and include inlets and outlets for cooling subsystem fluid.

[0069] At least one of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector may be a dichroic reflector, and the plurality of semiconductor devices of the light source may comprise an LED array. The LED array may comprise a first LED and a second LED, wherein the first LED and the second LED emit UV light with different peak wavelengths. The curing device may further comprise a quartz tube axially centered around the common focal point and concentrically surrounding the workpiece in the curing device.

[0070] In another embodiment, a photoreactive system for UV curing may include a power supply, a cooling subsystem, a light-emitting subsystem, and a UV light source disposed substantially at a second focal point of the first elliptical cylindrical reflector. The light-emitting subsystem may include coupling optics including a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector have a common focal point and are disposed on opposite sides of a workpiece.The photoreactive system may further comprise a controller having instructions stored in memory executable for emitting UV light from the UV light source, wherein, in the absence of a light source positioned at a second focal point of the second elliptical cylindrical reflector, the emitted UV light is reflected by at least one of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector and focused onto a surface of the workpiece. The controller may further comprise instructions executable for dynamically varying an intensity of the emitted UV light, and the photoreactive system may further comprise the UV light source located substantially at the second focal point of the first elliptical cylindrical reflector, wherein the emitted UV light comprises a beam of spatially constant intensity surrounding the workpiece.

[0071] With reference now to Fig. 11 illustrates a method 1100 for curing a workpiece, for example, an optical fiber, an optical fiber coating, or another type of workpiece. The method 1100 begins at 1110, where a workpiece may be drawn in a workpiece drawing step—in the case of an optical fiber, from a preform. The method 1100 then proceeds to 1120, where the workpiece is coated with a UV-curable coating or a UV-curable polymer system using a predetermined coating process.

[0072] Next, the method 1100 proceeds to 1130, where the workpiece may be UV cured. During UV curing at 1130, the workpiece may be pulled through the sample tube of one or more UV curing devices at 1132. For example, the one or more UV curing devices may include one or more curing devices 400, 500, 600, and / or 700 arranged linearly in series. Furthermore, the workpiece may be positioned along a common focal point of a dual elliptical reflector of the UV curing device, for example, a common focal point of a first elliptical cylindrical reflector and a second elliptical cylindrical reflector. UV curing the workpiece may further comprise, at 1134, emitting UV light from at least one LED array light source positioned at a second focal point of the first elliptical cylindrical reflector.The emitted UV light can be reflected by the first elliptical cylindrical reflector onto the surface of the workpiece at 1136 and reflected back onto the surface of the workpiece at 1138. Furthermore, the workpiece can be UV-cured in the absence of a light source positioned at a second focal point of the second elliptical cylindrical reflector. Accordingly, the emitted UV light can be uniformly directed onto a surface of the workpiece.

[0073] In the case of drawing and UV-curing optical fibers, the linear speed at which the optical fiber can be drawn can be very fast, exceeding, for example, 20 m / s. Arranging multiple UV-curing devices in series can thus allow the coated length of optical fiber to receive sufficient UV exposure dwell time to substantially complete curing of the optical fiber coating. In some cases, the usable length of the UV-curing phase (e.g., the number of UV-curing devices arranged in series) is determined by considering the production rate or drawing speed, or the linear speed of the optical fiber or workpiece. Thus, if the linear speed of the optical fiber is slower, the length or number of the UV-curing system phases can be shorter than in cases where the linear speed of the optical fiber is faster.In particular, using UV curing devices comprising a first elliptical cylindrical reflector and a second elliptical cylindrical reflector with a common focal point can potentially provide higher intensity and uniformity of UV light radiated and directed onto the surface of the workpiece, thereby providing both faster and more uniform curing of the workpiece. In this way, optical fiber coatings and / or inks can be UV-cured at higher production rates, thereby reducing manufacturing costs.

[0074] Complete UV curing of the optical fiber coating can impart physical and chemical properties such as strength, durability, chemical resistance, fatigue strength, and the like. Incomplete or insufficient curing can degrade product performance and other properties, potentially causing premature failure and loss of performance of the optical fiber. In some cases, the usable length of the UV curing stage (e.g., the number of UV curing devices arranged in series) is determined by considering the production rate or drawing speed, or the linear velocity of the optical fiber or workpiece. If the linear velocity of the optical fiber is slower, the length or number of the UV curing system stages can be shorter than in cases where the linear velocity of the optical fiber is faster.

[0075] Next, the method 100 proceeds to 1140, where it is determined whether additional coating steps are required. In some examples, dual or multi-layer coatings may be applied to the surface of the workpiece, for example, an optical fiber. As discussed above, optical fibers may be manufactured to include two concentric protective coating layers. For example, a bilayer coating may also be used, in which the workpiece may be coated with an inner layer, which, when cured, may have a soft and rubbery quality to minimize microbending attenuation, and an outer layer, which may be stiffer and suitable for protecting the workpiece (e.g., the optical fiber) from abrasion and environmental exposure (e.g., humidity, UV). The inner and outer layers may comprise a polymer system with initiators, monomers, oligomers, and other additives.If an additional coating step is to be performed, the method 110 returns to 1120, where the optical fiber or other workpiece (now coated with a UV-cured first layer) is coated by an additional coating step 1120 followed by an additional UV curing 1130. In . Fig.In Figure 11, for ease of illustration, each coating step is shown as an optical fiber coating step 1120. However, not every coating step needs to be identical, so each coating step may apply different types of coatings, different coating compositions, different coating thicknesses, and impart different coating properties to the workpiece. Furthermore, the coating process 1120 may utilize different processing conditions (e.g., temperature, coating viscosity, coating method). Similarly, UV curing the workpiece 1130 may involve a range of processing conditions for different coating layers or steps.For example, in different UV curing steps, processing conditions such as UV light intensity, UV exposure time, UV light wavelength spectra, UV light source, and the like may be changed depending on the type of coating and / or coating properties.

[0076] Additional coating steps may also include printing or applying a UV-curable ink or varnish to the surface of the workpiece, for example, for coloring or identification purposes. Printing may be performed using a predetermined printing process and may involve one or more multiple printing stages or steps. Thus, UV curing at 1130°C may include UV curing of an ink or varnish on the surface of the workpiece.Analogous to the UV curing step of the one or more coatings of optical fibers, the ink or varnish is UV cured by drawing the workpiece positioned at the common focal point of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector of one or more UV curing devices arranged in series, during which UV light is emitted by the LED array light sources of the UV curing device(s) and directed by the dual elliptical cylindrical reflectors onto the surface of the optical fiber at the common focal point.

[0077] If there are no additional coating steps, the method 1100 proceeds to 1180, where any post-UV curing process steps are performed. For example, if the workpiece comprises an optical fiber, post-UV curing process steps may include a cable or ribbon construction, combining multiple coated and printed, and UV-cured optical fibers into a flat ribbon or a larger diameter cable comprised of multiple fibers or ribbons. Other post-UV curing process steps may include coextrusion of an outer jacket or sheath of cables and ribbons.

[0078] In this way, a method for hardening a workpiece may include drawing the workpiece along a common focal point of a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, emitting UV light from a light source positioned at a second focal point of the first elliptical cylindrical reflector, reflecting the emitted UV light from the first elliptical cylindrical reflector to a surface of the workpiece, and reflecting the emitted UV light from the second elliptical cylindrical reflector back to the surface of the workpiece. The UV light may be emitted from the light source at the second focal point of the first elliptical cylindrical reflector in the absence of a light source positioned at a second focal point of the second elliptical cylindrical reflector.Furthermore, drawing the workpiece along the common focal point may comprise drawing at least one of the optical fiber, ribbon, or cable with at least one of the UV-curable coating, polymer, or ink. The LED array further comprises a first LED and a second LED, wherein the first LED and the second LED emit UV light at different peak wavelengths.

[0079] The method may comprise dynamically varying an intensity of the emitted UV light and positioning the UV light source substantially at the second focal point of the first elliptical cylindrical reflector, wherein the emitted UV light comprises a beam of spatially constant intensity surrounding the workpiece.

[0080] In another embodiment, a method may include positioning a workpiece along a first inner axis of a reflector, the reflector comprising first curved surfaces having a first curvature and second curved surfaces having a second curvature, positioning a light source along a second inner axis of the reflector, and emitting light from the light source, wherein the emitted light is reflected from the first curved surfaces and from the second curved surfaces onto the workpiece. The first inner axis may coincide with a first focal point of the first curved surfaces and a focal point of the second curved surfaces, and the second inner axis may coincide with a second focal point of the first curved surfaces.Furthermore, the emitted light can be reflected individually by the first curved surface before reaching the workpiece, and the emitted light can be reflected multiple times by the second curved surface before reaching the workpiece. Furthermore, the light source can comprise an LED array comprising a first LED and a second LED, wherein the first LED emits light at a first peak wavelength and the second LED emits light at a second peak wavelength.

[0081] It should be understood that the configurations disclosed herein are exemplary in nature and that these specific embodiments are not intended to be limiting, as numerous modifications are possible. For example, the above embodiments may be used with workpieces other than optical fibers, cables, and ribbons. Furthermore, the UV-curing devices and systems described above may be integrated with existing manufacturing equipment and are not designed for a specific light source. As described above, any suitable light generator may be used, such as a microwave-powered lamp, LEDs, LED arrays, and mercury vapor lamps. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various configurations, as well as other features, functions, and / or properties disclosed herein.

[0082] It should be noted that the example process flows described herein can be used with various UV curing devices and UV curing system configurations. The process flows described herein may represent one or more of any number of processing strategies, such as continuous, batch, semi-batch, and semi-continuous processing, and the like. Thus, various steps, operations, or functions may be performed in the sequence shown, in parallel, or in some cases skipped. Similarly, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. Depending on the particular strategy used, one or more of the steps or functions shown may be performed repeatedly.It is understood that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not intended to be limiting, as numerous modifications are possible. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0083] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as encompassing the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also considered to be included within the subject matter of the present disclosure.

Claims

[1] Curing device comprising: a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, the first elliptical cylindrical reflector and the second elliptical cylindrical reflector being arranged to have a common focal point, and a light source positioned at a second focal point of the first elliptical cylindrical reflector, wherein light emitted by the light source is reflected by the first elliptical cylindrical reflector to the common focal point and reflected back by the second elliptical cylindrical reflector to the common focal point, wherein a light source is absent at a second focal point of the second elliptical cylindrical reflector. [2] The curing apparatus according to claim 1, wherein a major axis of the first elliptical cylindrical reflector is larger than a major axis of a second elliptical cylindrical reflector. [3] The curing apparatus according to claim 2, wherein a minor axis of the first elliptical cylindrical reflector is larger than a minor axis of the second elliptical cylindrical reflector. [4] The curing apparatus according to claim 3, wherein the major axis of the second elliptical reflector and the minor axis of the second elliptical reflector are the same. [5] The curing apparatus of claim 1, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector are adapted to receive a workpiece and are disposed on opposite sides of the workpiece. [6] Curing device according to claim 1, wherein: elliptical surfaces of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector meet and are connected, thereby forming upper and lower edges near a central position of the curing device and extending along a major axis length of the first elliptical cylindrical reflector and a major axis length of the second elliptical cylindrical reflector, the elliptical surfaces of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector extending outwardly from the upper and lower edges to each side of the curing device where the elliptical cylindrical reflectors connect to a housing for the light source; the light source comprises a power source, a controller, a cooling subsystem, and a light-emitting subsystem, wherein the light-emitting subsystem comprises coupling electronics, coupling optics, and a plurality of semiconductor devices; and the housing contains the light source and includes inlets and outlets for cooling subsystem fluid. [7] The UV curing device according to claim 1, wherein at least one of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector is a dichroic reflector. [8] The curing apparatus of claim 6, wherein the plurality of semiconductor devices of the light source comprise an LED array. [9] The curing device of claim 8, wherein the LED array comprises a first LED and a second LED, the first LED and the second LED emitting UV light having different peak wavelengths. [10] The curing apparatus of claim 6, further comprising a quartz tube axially centered about the common focal point and concentrically surrounding the workpiece in the curing apparatus. [11] Photoreactive system for UV curing, comprising: a power supply; a cooling subsystem; a light-emitting subsystem comprising: Coupling optics comprising a first elliptical cylindrical reflector and a second elliptical cylindrical reflector, wherein the first elliptical cylindrical reflector and the second elliptical cylindrical reflector have a common focal point and are arranged on opposite sides of a workpiece, and a UV light source positioned substantially at a second focal point of the first elliptical cylindrical reflector, wherein the second focal point of the first elliptical cylindrical reflector does not include a focal point of the second elliptical cylindrical reflector; and a controller comprising instructions stored in memory executable for emitting UV light from the UV light source, wherein the emitted UV light, in the absence of a light source positioned at a second focal point of the second elliptical cylindrical reflector, is reflected by at least one of the first elliptical cylindrical reflector and the second elliptical cylindrical reflector and is focused onto a surface of the workpiece. [12] The photoreactive system of claim 11, wherein the controller further comprises instructions executable to dynamically vary an intensity of the emitted UV light. [13] The photoreactive system of claim 11, wherein the emitted UV light comprises a beam of spatially constant intensity surrounding the workpiece. [14] Method comprising: Positioning a workpiece along a first inner axis of a reflector, the reflector comprising first curved surfaces having a first curvature and second curved surfaces having a second curvature; Positioning a light source along a second inner axis of the reflector; and Emitting light from the light source, wherein the emitted light is reflected from the first curved surfaces and from the second curved surfaces onto the workpiece, wherein the first inner axis coincides with a first focal point of the first curved surfaces and a focal point of the second curved surfaces, wherein the second inner axis coincides with a second focal point of the first curved surfaces and wherein the light source is positioned at the second focal point of the first curved surfaces, wherein no light source is positioned at the focal point of the second curved surfaces. [15] The method of claim 14, wherein the emitted light is individually reflected from the first curved surface before reaching the workpiece. [16] The method of claim 15, wherein the emitted light is reflected multiple times by the second curved surface before reaching the workpiece. [17] The method of claim 16, wherein the light source comprises an LED array comprising a first LED and a second LED, wherein light is emitted from the first LED at a first peak wavelength and from the second LED at a second peak wavelength.

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