WO2011075084A1

WO2011075084A1 - Method and apparatus for making polymeric resin-based optical components via ultra-violet radiation

Info

Publication number: WO2011075084A1
Application number: PCT/SG2010/000470
Authority: WO
Inventors: Choong Whye Kwok; Jiun Yuen Hoh
Original assignee: Choong Whye Kwok; Jiun Yuen Hoh
Priority date: 2009-12-16
Filing date: 2010-12-16
Publication date: 2011-06-23
Also published as: SG172492A1

Abstract

The present invention provides methods and apparatuses for fabricating optical components. A method for fabricating optical components comprises dispensing a measured amount of radiation sensitive liquid onto a surface at a designated location; aligning a replicator with the designated location of the surface using an alignment means, wherein the replicator having one end defining a pattern in negative form facing the surface; performing imprinting by impressing the replicator against the liquid on the surface; curing the impressed liquid through irradiation; and removing the replicator. The optical component is imprinted with the pattern on the surface. An optical component fabrication apparatus is also provided.

Description

METHOD AND APPARATUS FOR MAKING POLYMERIC RESIN-BASED OPTICAL COMPONENTS VIA ULTRA-VIOLET RADIATION

Field of the Invention

[0001] The present invention generally relates to optical components. More particularly, the present invention relates to a method and apparatus for making polymeric resin-based optical components.

Background of the Invention

[0002] Optical lenses are often made of glass, plastics or crystals. Glass lenses are traditionally fabricated by grinding, optical polishing and lapping to shape from a glass block. An alternative to traditional grinding and polishing for glass lens fabrication is glass injection molding. For example, aspheric glass illuminator (condenser) lenses both large and small can be made by glass injection molding, which is carried out generally in high temperature. For precision optics, small glass lens elements can be fabricated using molds of heat-resistant materials such as carbide alloys. The molds for lens array require more machining steps to make and they must be precisely machined, these in turn increases cost. Further, glass injection molding is not ubiquitous currently as the capital investment in customized machines and equipments have rendered this technique unfitting for commercialization on an economic scale.

[0003] One glass lens fabricating process employs a bulging mold that consists simply a hole in a piece of metal (or an array of holes in the case of the bulging mold for a microlens array). The bulging mold is pressed into molten glass that is heated above its transition temperature; the glass then bulges into the holes with the shape of the glass surface determined by relaxation induced by the forming stress. When the conditions are right, the bulge of glass takes a spherical shape. As shown in FIG. 1, the hole 1 in the metal plate 2 serves as an effective mold for glass subheadlenses 3. The edge of the hole is configured to be sharp (top), have a radius (center) or be chamfered (bottom). [0004] Plastics lenses on the other hand, can be easily manufactured by variety ways including injection molding, machining and casting. For plastic injection molding, optical grade polymer resins (such as polycarbonate, PMMA, polystyrene), commonly available in high purity solid granules form, are melted in a heated barrel and forced into a cavity, which is a negative form of the optical lens under intense pressure. High purity resins are preferred for better optical performance. Such resins commonly has relatively lower melting point than glass, it can be processed at a relatively lower operating cost than glass injection molding due largely to ease of operation as well as lower capital investment on equipments and machines. Upon cooling/curing, the solidified resins assume the shape and geometry of the cavity. Regarding of machining, lens can be machined from a block of clear plastics. The machining is usually done on a diamond lathe to ensure a polished profile required of an optically functional lens. With respect to casting, liquid polymer melt is "poured" into a mold and a lens is casted.

[0005] For crystals (e.g., ziconia), lens made from these brittle materials are machined to shape and form.

Summary of the Invention [0006] In accordance with one aspect of the present invention, there is provided A method for fabricating optical components. The method comprises dispensing a measured amount of radiation sensitive liquid onto a surface at a designated location; aligning a replicator with the designated location of the surface using an alignment means, wherein the replicator having one end defining a pattern in negative form facing the surface; performing imprinting by impressing the replicator against the liquid on the surface; curing the impressed liquid through irradiation; and removing the replicator. The optical component is thus imprinted with the pattern on the surface.

[0007] In one embodiment, the radiation may be UV-radiation. [0008] In another embodiment, the liquid is sensitive to a range of wavelength of the radiation. It is possible that the liquid is sensitive to a narrow band wavelength of the radiation. It is also possible that the liquid may be UV-radiation sensitive liquid, such as liquid polymer resin. Further, the liquid polymer resin may be thermoset resin.

[0009] In another embodiment, the liquid is dispensed on the pattern in negative form of the replicator first. Alternatively, the liquid may be dispensed on a surface of a substrate. Further, the substrate is a LED or a thin film. The thin film may be a cyclic olefin copolymer based firm. More specifically, the thin film may be a polycarbonate based film.

[0010] The method according to claim 1, wherein the replicator is UV-radiation transmissive replicator. [0011] In yet a further embodiment, the optical components are any of the group consisting of imaging lenses, flash lenses, light guides, illumination lenses, and cosmetics or aesthetics or decorative imprints.

[0012] In another aspect of the present invention, there is also provided an optical component fabricated by the aforesaid method.

[0013] In a further aspect of the present invention, there is provided an optical components fabrication system comprises an alignment means having a upwardly faced surface; a liquid dispensing means operationally dispenses a measured amount of radiation sensitive liquid on a designated location on the upwardly faced surface; a radiation source for emitting radiation for curing the radiation sensitive liquid; a replicator having one end defining a pattern in negative form. The liquid is dispensed on the designated location on the upwardly faced surface, the replicator aligns with the designated location and impresses the dispensed liquid against the surface, and the radiation source then emits radiation to cure the liquid thereby forming a patterned lens after the replicator is removed. [0014] The objectives and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings.

Brief Description of the Drawings

[0015] Preferred embodiments according to the present invention will now be described with reference to the Figures, in which like reference numerals denote like elements.

[0016] FIG. 1 shows a glass lens molding process in the prior art; [0017] FIGs. 2A-2D show a method of fabricating an optical component in accordance with one embodiment of the present invention;

[0018] FIGs. 3A-3B shows the imprinting and removing operations of the method in accordance with one embodiment of the present invention; and [0019] FIGs. 4A-4B shows an illustrative example of the application of the present invention.

Detailed Description of the Invention

[0020] The present invention may be understood more readily by reference to the following detailed description of certain embodiments of the invention. [0021] Throughout this application, where publications are referenced, the disclosures of these publications are hereby incorporated by reference, in their entireties, into this application in order to more fully describe the state of art to which this invention pertains.

[0022] The present invention provides a process for fabricating optical components through printing a three dimensional (3D) object. The "printing" referred to in the present invention relates to a method of forming an optical component having a pattern defined thereon through dispensing liquid on a surface, forming a design/pattern on the liquid thereon and curing the liquid to form the optical component. The immediate raw material for printing the optical components is in liquid form at room temperature. The liquid is generally light/radiation curable, and preferably, ultra-violet (UV) radiation curable liquid. The printing process is carried out without the need of high temperature setup and process. The process comprises aligning substrate to replicator, applying a measured amount of optical resin, imprinting under pressure, cure under radiation and removing replicator, thereby a cured resin is formed on the surface with a desired pattern. "Imprint" has a same or substantially the same meaning in the present context.

[0023] FIGs. 2A-2D illustrate the printing process for fabricating optical components in accordance with one embodiment of the present invention. The optical components include optical lens, such as a Fresnel lens. Referring first to FIG. 2A, the method comprises aligning the substrate 30 with the replicator 20 that at one downwardly faced end surface has a pattern in negative form 21. As shown, the replicator 20 is a die for impressing upon to form a lens component defining the pattern. The replicator 20 is UV transmissive that allows UV light to irradiate there through. The replicator 20 can be made of UV transmissive crystals, such as zirconia, glass and etc. on which the negative form of the object lens can be formed. The substrate 30 is placed on a workstation that provides physical support and movement so as to allow proper alignment of the substrate 30 with the replicator 20; the workstation is not shown herein and can be any known one in the art as long as it is capable of providing such requisite support and movement. Likewise, the alignment can be achieved by any means known in the art; for example laser light, jig and fixtures, vision comparator, etc.

[0024] Referring now to FIG. 2B that illustrates another step of the printing process. A measured amount of UV curable optical resin liquid 41 is applied onto the designated location on the substrate 30 by an applicator 40. UV-curable epoxy and polyurethane (both optical grade), for example, are suitable candidates as the optical resin liquid 41. The applicator 40 can be any known means as long as it can accurately provide the desire amount of UV curable optical resin liquid 41. The amount of fluid 41 dispensed is carefully controlled. Inadequate amount of fluid 41 dispensed results in a "short" imprint where the imprinted lens is not wholly formed. Such defect often affects the optical quality, which is often not allowed. On the other hand, excessive fluid dispensed resulting in spillage beyond the boundary of the intended lens geometry, but it would not affect the optical performance of the cured lens. A peristaltic pump (not shown), for example, can be used for dispensing a required amount of the liquid 41. Other fluid dispensing device and apparatus commonly known in the art may also be desired. It is to be noted that the manner by which the liquid resin is dispensed on the substrate is also critical for the present invention because improper dispensing may result in air getting trapped as bubbles or voids in the cured lens rendering it a defected lens.

[0025] Preferably, the printing process is carried out in a controlled environment that has no or minimal external light (that carries stray UV stream) enters thereto.

[0026] Referring now to FIG. 2C that illustrates a further step of the printing process. The replicator 40 is lowered down to impress on the UV curable optical resin liquid 41 through the pressure applicator 60. The liquid 41 fills to conform the cavity of the negative form of the pattern 21. When necessary, a vibration can be applied to ensure a better conformance of the liquid 41 with the cavity. The impressed liquid 41 is then cured by radiation emitted by a radiation source 50. Preferably, the radiation is UV-radiation. The pressure applicator 60 remains impressed on the liquid 41. The light source and pressure applicator can be any know ones in the art. As the replicator 40 is made of a UV- light transmissive material, the UV-light is able to reach the liquid 41 through the replicator 40 for curing it. Commonly, UV-curable epoxy, for example, is curable in a matter of a few seconds. It is known in the art that the liquid 41 can be customized to respond to a specific range of wavelength of the radiation. A narrow band of wavelength is can be desired to avoid liquid 41 being cured unnecessarily by any foreign radiation during the imprinting process.

[0027] FIG. 2D illustrates yet a further step of the printing process. The replicator 40 is removed once the liquid 40 is cured under UV-light. A patterned optical component 31 is formed on the substrate 30.

[0028] In accordance with the present invention, the substrate 40 includes any thin films of any suitable materials, or any rigid objects such as a commercially available LED. In one embodiment, the substrate 40 is a cyclic olefin copolymer (COC) based film where the optical component is formed thereon. Once the optical component is formed, it can easily be peeled off from the substrate 40 as an individual optical component, which can be attached on the surface of desired application via any optically clear bonding means, such as adhesive, glue and etc. In another embodiment, the substrate 40 is a polycarbonate (PC) based film, which is optically transparent that allows the printing process to apply on a same area on other side of the substrate 40 to form a two-sided optical component. For the two-sided optical components, each side may have a different pattern to suit the application. In yet a further embodiment, the optical component is printed on a desired application directly. As the optical component according to the present invention is not fabricate in a high temperature environment, nor is it require any high speed machining, the optical component can be formed directly onto almost any applications of desired.

[0029] It is understood that the above substrates are provided by way of example, not limitations. The purpose of the substrates is served as a medium that provides a surface for dispensing the liquid 41 during the lens imprinting process. Depending on the type and application of the lens, the substrates can be optional.

[0030] Now referring to FIGs. 3A and 3B, there is provided an exemplary application of the optical component printing process of the present invention. The substrate is an LED 60, and a lens 65 is formed on LED out-coupling surface directly by the aforedescribed imprinting process.

[0031] FIGs. 4A and 4B illustrate the printing process in accordance with an alternative embodiment of the present invention. Particularly, FIG. 4A shows a liquid deposition/dispensing process and FIG. 4B shows an impressing process of the printing process. In this embodiment, the replicator 20 is oriented with the pattern in negative form 21 (hereinafter referred to as "the negative pattern") facing upward. As shown in FIG. 4A, the replicator 20 is first aligned with the applicator 40, then the liquid 41 of a measured amount is dispensed through the applicator 40 on the replicator 20 over the pattern in negative form 21. The applicator 40 starts to dispense the liquid 41 from the center cavity of the negative pattern 21. The dispensing speed of the fluid 41 is also careful controlled to ensure that fluid 41 flows over the entire cavity of the negative pattern 21 and conform thereto. Once the measured amount of fluid 41 is dispensed, the replicator 20 is brought to align with the substrate 30 that is positioned above the replicator 20. The replicator 20 is then brought towards against the facing surface of the substrate 30 for impressing the liquid 41 onto the surface of the substrate 30. A UV light irradiates the liquid 41 from the top through the substrate 30. Once the liquid 41 is cured, the patterned optical component is formed on the bottom side of the substrate 30. [0032] In this embodiment, the UV-radiation does not irradiate through the replicator 20, and thus, the replicator 20 can also be made of any non-UV-transmissive material, such as an opaque material, such as steel. On the other hand, as the UV-radiation is emitted from the top, it is preferred that the substrate 30 is made up of UV-transmissive material so that the UV-radiation can irradiate through the substrate 30 to cure the liquid 41.

[0033] In a further embodiment, the printing method in accordance with the present invention can be used to fabricate a two-sided optical component through combining the processes of FIGs. 2A-2D with FIGs. 4A-4B. Accordingly, two replicators 20 oriented in an opposing manner are provided, where the top replicator is used to form one side of the two-sided optical component and the bottom replicator is used to form the other side. It is possible that the printing process can fabricate the two-sided lens that includes the pattern on one side that is different from another.

[0034] In yet a further embodiment, a two sided lens is formed by the printing method without any substrate 40. The liquid 41 can be dispensed directly on a patterned surface of an upwardly faced replicator for forming a first side of the lens. With an adequate amount of liquid 41 dispensed, a downwardly faced replicator is impressed on the upwardly faced replicator with the desired pattern properly aligned, once the liquid 41 is cured through radiation, the two-sided lens is formed. [0035] In an alternative embodiment, fluid 41 for the second side of the lens can be dispensed only after the first side of the lens is cured and formed.

[0036] The printing process may include applying a vibration to the printing process. In one embodiment, the vibration is an ultrasonic vibration. [0037] The present invention also provides an apparatus for fabricating optical components by printing; thus the apparatus is in principle different from the ones known in the art including molding and stamping. The apparatus comprises a substrate supporting and movement means, a UV source, a pressure applicator, and a replicator/die.

[0038] While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Alternative embodiments of the present invention will become apparent to those having ordinary skill in the art to which the present invention pertains. Such alternate embodiments are considered to be encompassed within the spirit and scope of the present invention. Accordingly, the scope of the present invention is described by the appended claims and is supported by the foregoing description.

Claims

CLAIMS What is claimed is:

1. A method for fabricating optical components, comprising: dispensing a measured amount of radiation sensitive liquid onto a surface at a designated location; aligning a replicator with the designated location of the surface using an alignment means, wherein the replicator having one end defining a pattern in negative form facing the surface; performing imprinting by impressing the replicator against the liquid on the surface; curing the impressed liquid through irradiation; and removing the replicator, thereby the optical component is imprinted with the pattern on the surface.

2. The method according to claim 1 , wherein the radiation is UV-radiation.

3. The method according to claim 1, wherein the liquid is sensitive to a range of wavelength of radiation.

4. The method according to claim 1, wherein the liquid is sensitive to a narrow band wavelength of radiation.

5. The method according to claim 1, wherein the liquid is dispensed on the pattern in negative form of the replicator first.

6. The method according to claim 1, wherein the liquid is dispensed on a surface of a substrate.

7. The method according to claim 1 , wherein the substrate is a LED.

8. The method according to claim 1, wherein the substrate is a thin film.

9. The method according to claim 8, wherein the thin film is a cyclic olefin copolymer based firm.

The method according to claim 9, wherein the thin film is a polycarbonate based film.

The method according to claim 1, wherein the UV-radiation sensitive liquid is liquid polymer resin.

The method according to claim 11, wherein the liquid polymer resin is thermoset resm.

13. The method according to claim 1, wherein the replicator is UV-radiation transmissive replicator.

14. The method of claim 1, wherein the optical components is any one selected from the group consisting of imaging lenses, flash lenses, light guides, illumination lenses, and cosmetics or aesthetics or decorative imprints.

15. An optical component fabricated by claim 1.

16. An optical components fabrication system comprising: an alignment means having a upwardly faced surface; a liquid dispensing means operationally dispenses a measured amount of radiation sensitive liquid on a designated location on the upwardly faced surface; a radiation source for emitting radiation for curing the radiation sensitive liquid; a replicator having one end defining a pattern in negative form; wherein the liquid is dispensed on the designated location on the upwardly faced surface, the replicator aligns with the designated location and impresses the dispensed liquid against the surface, and the radiation source then emits radiation to cure the liquid thereby forming a patterned lens after the replicator is removed.