The present invention relates to a method for manufacturing a lens having a functional nanopattern, which increases light transmittance by minimizing reflections from the surface of the lens.
In general, when light passes through the interface between two media having different refractive indices, the light is subjected to Fresnel loss, attributable to the difference in the refractive indices of the media, and loss caused by total internal reflection.
Fresnel loss occurs when a portion of light is reflected from the interface between surfaces having discontinuous refractive indices, whereas total internal reflection refers to the phenomenon in which light that travels from one medium having a higher refractive index into another medium having a lower refractive index is reflected from the interface, rather than passing through it, if the incident angle is greater than the critical angle.
Referring to
Rays of light that are reflected into the medium (arrows “B” and “C”) cause loss, since they are absorbed by the medium or travel in an unintended direction through it.
In order to reduce reflections occurring at the surface of the medium as described above, a method of applying a single-layer or multilayer thin film on the surface of the medium in a vacuum chamber is currently used. This method is based on destructive interference of light that is reflected from the interface coated with the thin film, and a multilayer thin film is generally used in order to realize an effect throughout the entire range of visible light.
The method of applying the thin film on the surface of the medium has problems such as low productivity and high cost.
In addition, another approach for reducing reflections occurring at the surface of the medium includes a method of using a functional nanopattern. The functional nanopattern is made of a photonic crystal pattern. “Photonic crystal pattern” refers to a structure in which different refractive indices are periodically repeated in one or more directions. The photonic crystal pattern is not diffracted, since its period does not exceed the half of the wavelength. If the photonic crystal structure is properly selected, the variation in the diffraction index between the two media, which have different diffraction indices, is gradual, thereby decreasing Fresnel reflection and significantly decreasing total reflection. Consequently, when light is emitted from a medium into the air, it is possible to significantly increase light efficiency.
Methods of forming such a photonic crystal pattern in the surface of a medium include E-beam radiation, X-ray lithography, focused ion beam, laser hololithography, and the like. However, there is a problem in that application to a wide surface of the medium incurs high cost.
Consequently, an approach of forming a photonic crystal pattern using nano imprinting, which can reduce cost, has been developed.
First, as shown in
Afterwards, as shown in
Subsequently, as shown in
Afterwards, as shown in
However, the foregoing method of forming a photonic crystal pattern using nano-imprinting has a problem in that it is difficult to apply this method to a lens having a curved shape, since a planar mold member and a planar substrate must be used.
An object of the present invention is to provide a method for manufacturing a lens having a functional nanopattern, in which a nanopattern can be formed in the surface of a lens having a curved shape in order to increase light transmittance by minimizing reflections from the surface of the lens.
Another object of the present invention is to provide a method for manufacturing a lens having a functional nanopattern, which can increase productivity and reduce manufacturing costs.
The present invention pertains to a lens characterized by having a curved portion through which light passes, the curved portion having defined therein a photonic crystal pattern that can minimize reflections of light.
The photonic crystal pattern is characterized in that a polymer that forms the photonic crystal pattern in the surface is attached to the surface of the curved portion.
The present invention provides a method for manufacturing a lens having a functional nanopattern. The method includes a first step of forming a photonic crystal pattern on a stamper; and a second step of forming a photonic crystal pattern in the surface of a second polymer attached to the surface of a curved portion of a lens by pressing the stamper against the curved portion of the lens.
In an embodiment of the invention, the first step includes a step of forming a photonic crystal pattern on a mold member; and a step of forming a photonic crystal pattern on a first polymer attached to the surface of a curved portion of a lens core by pressing the mold member against the lens core.
The stamper is the lens core to which the first polymer, with the photonic crystal pattern formed therein, is attached.
In another embodiment of the invention, the stamper is a mold member, which is made of a material that stays deformable after being cured from a liquid to a solid.
In a further embodiment of the invention, the first step includes a step of applying a pattern-forming material on a curved portion of the lens core; a step of applying an optical polymer on the surface of the pattern-forming material; forming a pattern hole in the optical polymer, the pattern hole conforming to the photonic crystal pattern; forming the photonic crystal pattern in the pattern-forming material by etching; and removing the optical polymer. The stamper is a lens core to which the pattern-forming material, with the photonic crystal pattern formed therein, is attached.
As described above, the present invention has an effect such that reflection loss can be minimized by attaching a polymer having a photonic crystal pattern to the surface of a curved portion of a lens, thereby increasing light transmittance.
The present invention will, now be described, more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments thereof are shown.
Referring to
First, as shown in
In addition, a liquid mold member 104 is applied to a predetermined thickness on the surface of the base substrate 100 on which the photonic crystal pattern 102 is formed. Here, it is preferred that the mold member 104 be made of a material, such as Polydimethylsiloxane (PDMS), that can stay flexible even after being cured from a liquid to a solid.
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The mold member 104 retains a deformable flexible property due to its characteristics, even after being cured into a solid.
Afterwards, as shown in
Here, it is preferred that the first polymer 112 be implemented as a photocurable polymer that cures when light is radiated thereon. A material that has excellent bonding strength to the plate 120 and is easily detachable from the mold member 104 can be selected. In addition, it is preferred that the inner surface of the curved portion 122 of the plate 120 be pretreated in order to increase the bonding strength to the first polymer 112.
In addition to the photocurable polymer, a thermal polymer that cures when heat is applied can be used as the first polymer 112. That is, the first polymer 112 can be implemented as a polymer that is curable in response to heat or light.
In addition, as shown in
Afterwards, the first polymer 112 is cured by radiating ultraviolet rays on the first polymer 112 if it is a photocurable polymer or applying heat on the first polymer 112 if it is a thermal polymer, and the mold member 104 is removed from the first polymer 112. Consequently, the first polymer 112, having the same curved shape as that of the curved portion of the lens, is attached to the curved portion 122 of the lens core 120, and the photonic crystal pattern 130 is formed in the surface of the first polymer 112.
Here, the photonic crystal pattern 130 is formed as a hole pattern that is inverse to the pillar pattern of the photonic crystal pattern 110 formed on the mold member 104.
The following steps are performed using the lens core, to which the first polymer having the photonic crystal pattern is attached, as a stamper.
Afterwards, as shown in
Although the curved portion of the lens has been described as being convex in this embodiment, this is not intended to be limiting. Rather, various shapes, such as a concave shape, a spherical shape, or an aspherical shape, can be applied.
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Since the photonic crystal pattern 132 can be formed in the surface of the curved portion 142 of the lens 140 through the foregoing process, it is possible to minimize reflection loss and increase light transmittance.
Referring to
First, as shown in
The mold member 170 has the photonic crystal pattern 172, which is formed in the surface thereof through the same process as the process that is used to form the photonic crystal pattern 110 in the surface of the mold member 104, which was described in the foregoing embodiment. Here, it is preferred that the photonic crystal pattern 172 have the form of a hole pattern.
The polymer 160 is implemented with a material that has excellent bonding strength to the surface of the lens 150 and is easily detachable from the mold member 104.
In this embodiment, the mold member is itself used as a stamper.
Afterwards, as shown in
Consequently, a photonic crystal pattern 162 the same as the photonic crystal pattern 172 in the mold member 170 is transferred to the surface of the polymer 160. Here, the photonic crystal pattern 162 has a pillar pattern shape, since it is replicated from the photonic crystal pattern 172, which has a hole pattern shape.
Afterwards, the first polymer 160 is cured by radiating ultraviolet rays thereon if a photocurable polymer is used, or by applying heat thereon if a thermal polymer is used.
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Subsequently, as shown in
Afterwards, as shown in
Consequently, a pattern hole 240 that conforms to the photonic crystal pattern formed in the glass mold member 250 is formed in the optical polymer 230. The pattern hole 240 has a hole pattern shape, since it is replicated from the photonic crystal pattern, which has a pillar pattern shape.
Afterwards, when heat is applied or ultraviolet rays are radiated through the glass mold member 250, the optical polymer 230 cures, and the pattern hole 240 is formed in the optical polymer 230 such that it penetrates the optical polymer 230.
In this state, as shown in
When the residual layer 235 is removed as described above, an etching process is performed.
The optical polymer 230 acts as a mask, and a photonic crystal pattern 260 is formed in the pattern-forming material 220 through the pattern hole 240 that is formed in the optical polymer 230.
Afterwards, as shown in
While the present invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in forms and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.
Number | Date | Country | Kind |
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10-2008-0088412 | Sep 2008 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR2009/000416 | 1/29/2009 | WO | 00 | 5/26/2011 |