Optical lens and lighting device using the same

An optical lens capable of miniaturization and capable of easily implementing various optical characteristics and a lighting device using the same are provided. The optical lens includes a lens body including an incident surface and an emitting surface; and a plurality of nano holes that extend in a direction from the incident surface toward the emitting surface, and is formed to communicate with at least one of the incident surface or the emitting surface. In particular, the plurality of nano holes change a phase of light that is incident on the lens body.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No. 10-2019-0157951 filed on Dec. 2, 2019, which application is herein incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to an optical lens and a lighting device using the same. More specifically, it relates to an optical lens capable of miniaturization and capable of easily implementing various optical characteristics and a lighting device using the same.

2. Description of the Related Art

A meta structure refers to a structure designed and manufactured to have artificial characteristics that do not naturally exist by designing an appropriate geometric periodic structure using existing materials in a broad sense.

The meta structure is an artificial structure in which values smaller than a wavelength of incident light are applied to a thickness, pattern, or period. The meta structure may realize various optical characteristics with a high response speed, and is advantageous for application in a compact device. Therefore, there are continued attempts to apply it to changing the transmission, reflection, polarization, phase, intensity, path, or the like of incident light.

FIG. 1is a schematic view showing a structure of an optical lens in the related art. The optical lens10according to the related art includes a support layer11and a plurality of nano pins12formed on the support layer11as a meta structure. The plurality of nano pins12are formed in a column shape on the support layer11. A phase of light is delayed depending on a thickness, height, formation cycle, or the like of the plurality of nano pins12to achieve required optical characteristics.

InFIG. 1, since the plurality of nano pins12are spaced apart from each other and disposed separately, the support layer11for supporting the plurality of nano pins12is essentially required, and thus there is a limit in reducing the overall size. In addition, it is necessary to fix the plurality of nano pins12on the support layer11through an adhesion process. Therefore, the overall manufacturing process increases, and it is relatively vulnerable to the external environment, thereby increasing the possibility of breakage or damage to the plurality of nano pins12.

Accordingly, there is a need for a method capable of miniaturizing optical lens while simplifying a manufacturing process and preventing breakage or damage caused by the external environment.

SUMMARY

Aspects of the present disclosure provide an optical lens with a meta structure that simplifies a manufacturing process and improves resistance to an external environment, and a lighting device using the same. However, aspects of the present disclosure are not restricted to those set forth herein. The above and other aspects of the present disclosure will become more apparent to one of ordinary skill in the art to which the present disclosure pertains by referencing the detailed description of the present disclosure given below.

According to an aspect of the present disclosure, an optical lens may include a lens body having an incident surface and an emitting surface; and a plurality of nano holes that extend in a direction from the incident surface toward the emitting surface, and is formed to communicate with at least one of the incident surface or the emitting surface. In particular, the plurality of nano holes may change a phase of light that is incident on the lens body.

The plurality of nano holes may be formed to communicate with both the incident surface and the emitting surface. The plurality of nano holes may have a diameter that is less than a wavelength of light to be transmitted, the diameter being a maximum distance between two opposing points disposed on a circumference of a longitudinal cross-section of the plurality of nano holes. The diameter may be less than a half of the wavelength of the light to be transmitted. The plurality of nano holes may have a constant diameter along the direction from the incident surface toward the emitting surface. Alternatively, at least one of the plurality of nano holes may be formed such that a diameter thereof changes at least partly in the direction from the incident surface toward the emitting surface.

A length of the plurality of nano holes in the direction from the incident surface toward the emitting surface may be greater than a diameter thereof. A pitch distance between the plurality of nano holes may be greater than a maximum value among diameters of the plurality of nano holes. The pitch distance between the plurality of nano holes may be less than twice the maximum value among the diameters of the plurality of nano holes.

The lens body may have a mesh shape in which regions other than the plurality of nano holes are connected to each other. Further, a support layer for supporting the lens body may be included. The support layer may be made of a transparent material through which the light is transmitted.

The plurality of nano holes may be divided into a plurality of groups, and at least one of the plurality of groups may have different optical characteristics from another. The optical characteristics may comprise at least one of focusing, divergence, or deflection of the light.

According to an aspect of the present disclosure, a lighting device may include a light source unit including at least one light source; and an optical lens for delaying a phase of light that is incident from the light source unit to cause the light to proceed in at least one direction. In particular, the optical lens may comprise a plurality of nano holes formed to extend in a direction in which the light is emitted.

The optical lens may convert the light that is incident from the light source unit to a substantially parallel light beam and emits it. The optical lens may cause a first portion of the light incident from the light source unit to be emitted with a different optical characteristic from a second portion of the light. The optical characteristic may comprise at least one of focusing, divergence, or deflection of the light.

According to the optical lens of the present disclosure and the lighting device using the same as described above, one or more of the following benefits may be provided. A meta structure formed on a lens body may be implemented as nano holes that are in communication with at least one surface of the lens body. Therefore, a manufacturing process for forming the meta structure may be simplified, and resistance to external impacts may be improved. The benefits of the present disclosure are not limited to the above-mentioned benefits, and other benefits not mentioned may be clearly understood by a person skilled in the art from the claims.

DETAILED DESCRIPTION

In some exemplary embodiments, well-known steps, structures and techniques will not be described in detail to avoid obscuring the disclosure.

Exemplary embodiments of the disclosure are described herein with reference to plan and cross-section illustrations that are schematic illustrations of idealized exemplary embodiments of the disclosure. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments of the disclosure should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. In the drawings, respective components may be enlarged or reduced in size for convenience of explanation.

Hereinafter, the present disclosure will be described with reference to the drawings for explaining an optical lens and a lighting device using the same according to exemplary embodiments of the present disclosure.

FIG. 2is a perspective view showing an optical lens according to an exemplary embodiment of the present disclosure.FIG. 3is a plan view showing the optical lens according to the exemplary embodiment of the present disclosure.FIG. 4is a sectional view taken along line A-A′ inFIG. 3. Referring toFIGS. 2 to 4, the optical lens100according to the exemplary embodiment of the present disclosure may include a lens body110and a plurality of nano holes120.

In the exemplary embodiment of the present disclosure, the optical lens100may be applied to a lighting device provided in a vehicle, drone, train, or the like, which needs to secure a field of view in low light conditions such as nighttime operation. However, this usage is only an example for helping the understanding of the present disclosure, and the present disclosure is not limited thereto. The optical lens100of the present disclosure may be applied to a device that requires various optical characteristics, such as an optical filter, an optical sensor, a display element, or the like as well as a lighting device.

The optical lens100of the present disclosure may adjust a refractive power by changing a phase of incident light to change a shape of a wave front that connects the same phase points of the light. Consequently, the optical lens100may allow optical characteristics of light such as focusing, divergence and deflection, or the like to be obtained. The optical characteristics implemented by the optical lens100of the present disclosure are not limited to examples described above, and it may include various optical characteristics required in a device to which the optical lens100of the present disclosure is applied.

For example, as shown inFIG. 5, the optical lens100of the present disclosure may convert an incident plane wave into a spherical wave and may emit light to allow the emitted light to be focused at a particular point. In addition, as shown inFIG. 6, the optical lens100of the present disclosure may convert an incident spherical wave that is incident from a point into a plane wave and may emit it as parallel light. InFIGS. 5 and 6, the dotted lines represent a wave front.

FIGS. 5 and 6as described above are examples where the optical lens100of the present disclosure performs a function of a convex lens. However, these examples are only for helping the understanding of the present disclosure, and the present disclosure is not limited thereto. The optical lens100of the present disclosure may perform functions of various types of lenses that focus, diverge, or deflect light depending on a degree of phase delay by each of the plurality of nano holes120.

Herein, the phase of light may be regarded as a relative angle of the light represented by a trigonometric function at a specific location and time. Delaying the phase of light may be understood to mean that the light in the form of waves is transmitted slower than without the delaying of the phase. Therefore, it may be understood that the degree to which the phase of light is delayed by each of the plurality of nano holes120is different where the light transmits faster or slower through one of the plurality of the nano holes120than another of the plurality of nano holes120. By appropriately adjusting the degree of the phase delay of the light by each of the plurality of nano holes120, i.e., by adjusting the degree of refraction, the shape of the wave front may be changed. Therefore, as described inFIGS. 5 and 6, the spherical wave may be converted to the plane wave or the plane wave may be converted to the spherical wave.

In the exemplary embodiment of the present disclosure, the optical lens100may adjust the refractive power depending on the degree of the phase delay imposed by each of the plurality of nano holes120to adjust the path of light. However, the present disclosure is not limited to adjusting the refractive power, and it is also possible to adjust light transmittance or the like that affects brightness.

The refractive power or a focal length implemented by the optical lens100of the present disclosure may be adjusted depending on dimensions of each of the plurality of nano holes120defined by a diameter d and a length t. Compared to the conventional lens of the related art that adjusts the refractive power by thickness or curvature of the lens, the refractive power of the optical lens100according to the present disclosure may be adjusted without changing overall size of the lens.

The lens body110may be formed of a material having a low absorption rate in a wavelength band of incident light in order to achieve a high transmittance. The higher the refractive index, the higher the light modulation efficiency may become and the smaller the plurality of nano holes120may be formed, thus reducing the burden on the manufacturing process.

The plurality of nano holes120may be formed to extend in a direction from an incident surface111of the lens body110toward an emitting surface112thereof, and may be formed to communicate with at least one of the incident surface111or the emitting surface112. The incident surface111and the emitting surface112of the lens body110may refer to a surface on which light is incident and a surface from which light is emitted, respectively. It may be understood that, depending on a device to which the optical lens100of the present disclosure is applied, one of both surfaces of the lens body110may become the incident surface111in a direction in which light is transmitted, and the other may serve as the emitting surface112.

Each of the plurality of nano holes120may delay (or adjust) the phase of the incident light to allow the required optical characteristics to be obtained. In the exemplary embodiment of the present disclosure, a meta structure may be formed in a hole shape instead of the column shape as in the related art, thereby simplifying the manufacturing process and improving the resistance to the impacts from the external environment.

In the exemplary embodiment of the present disclosure, both sides of the plurality of nano holes120may be formed to communicate with the incident surface111and the emitting surface112of the lens body110, respectively, so that the incident surface111and the emitting surface112of the lens body110are communicated with each other by the plurality of nano holes120. However, the present disclosure is not limited thereto. As shown inFIGS. 7 and 8, the plurality of nano holes120may be formed to communicate with either one of the incident surface111or the emitting surface112of the lens body110. In this case, a distance between a shielding surface of the incident surface111and the emitting surface112and the plurality of nano holes120may be determined based on a required light transmittance.

Openings121and122may be formed on both sides of the plurality of nano holes120to communicate with the incident surface111and the emitting surface112of the lens body110. Hereinafter, in the exemplary embodiment of the present disclosure, the opening121that communicates with the incident surface111of the lens body110is referred to as an incident side opening, and the opening122that communicates with the emitting surface112of the lens body110will be referred to as an emitting side opening.

The plurality of nano holes120may be formed using a process such as etching or lithography of the lens body110. The plurality of nano holes120may have different degrees of phase delay of light depending on the dimensions, and the dimensions of the plurality of nano holes120may be defined by a diameter d and a length t.

When the plurality of nano holes120are formed in the lens body110as described above, the lens body110may have a mesh shape in which regions other than the plurality of nano holes120are connected to each other. As a result, the possibility of breakage or damage may be reduced, and the resistance to the external impact such as shock, vibration, and/or heat may be increased as compared to the case where the meta structure is formed in the column shape.

Herein, the diameter d of the plurality of nano holes120may be defined as the longest distance between two opposing points disposed on an intersecting plane between the nano holes and a plane parallel to the incident surface111, the two opposing points constituting the circumference of the incident side opening121. In other words, the diameter d may be the maximum distance between two opposing points disposed on the circumference of a longitudinal cross-section of the plurality of nano holes. In the exemplary embodiment of the present disclosure, it is described as an example in which the incident side opening121is circular, and thus the diameter d may be understood as a diameter of a circle.

In the exemplary embodiment of the present disclosure, it is described as an example in which shape of the plurality of nano holes120is circular. However, depending on the degree of phase delay of the light, it may have various shapes such as a square and an oval. In this case, the diameter d may be the longest distance between the two opposing points located on the same plane as shown inFIGS. 9 and 10. As such, the diameter d may be understood as a representative feature size, a nominal dimension, a maximum width of the nano hole, or the like. The shape of the plurality of nano holes120is not limited to the example as described above, and may have a variety of shapes, such as a linear shape, a curved line, or a combination thereof, depending on the degree of the phase delay of the light.

The diameter d of the plurality of nano holes120may be smaller than the wavelength of the light to be transmitted. This is because the diameter d of the plurality of nano holes120that is sufficiently smaller than the wavelength of the light to be transmitted may be established as an effective medium theory, that is, a medium having an effective refractive index. In addition, this is to ensure that a range of the phase delay of the light encompasses whole 2π, i.e., 0 to 360 degrees, to allow phase delay for all angles to be possible.

For example, when the wavelength of the light to be transmitted is 100 to 1400 nm, the diameter d of the plurality of nano holes120may be 20 to 1000 nm. Here, when the wavelength of the light is 100 to 1400 nm, it is an example of the case where the optical lens100of the present disclosure is also applied to an optical filter or an optical sensor using infrared and ultraviolet light, including visible light. When the optical lens100of the present disclosure is applied to a lighting device using visible light, the diameter d of the plurality of nano holes120may be 20 to 400 nm.

The plurality of nano holes120may have different diameters d depending on the shape of the holes. When a maximum value of the diameters d of the plurality of nano holes120is formed to be less than half of the wavelength of the light to be transmitted, it satisfies the effective medium theory while allowing the range of the phase delay of the light to cover the entire 2π.

In addition, the length t of the plurality of nano holes120may be defined as the length of the hole in a direction from the incident surface111of the lens body110toward the emitting surface112thereof. When the incident side opening121and the emitting side opening122of the plurality of nano holes120are formed to communicate with the incident surface111and the emitting surface112of the lens body110, respectively, the length t of the plurality of nano holes120may correspond to a thickness of the lens body110. When either of both sides of the plurality of nano holes120is formed to communicate with one of the incident surface111or the emitting surface112of the lens body110, the length t of the plurality of nano holes120may be smaller than the thickness of the lens body110.

In the exemplary embodiment of the present disclosure, the lengths t of the plurality of nano holes120may be uniform for all of the plurality of nano holes120. However, the present disclosure is not limited thereto, and some of the plurality of nano holes120may have different lengths from others. The length t of the plurality of nano holes120may satisfy a condition that the range of the phase delay of the light encompasses the entire 2π while reducing light loss. To this end, the length t of the plurality of nano holes120may be formed to be greater than the diameter d.

For example, when the wavelength of the light to be transmitted is 100 to 1400 nm and the diameter d of the plurality of nano holes120is 20 to 1000 nm, the length t of the plurality of nano holes120may be 200 to 1200 nm. When the optical lens100of the present disclosure is applied to a lighting device using visible light and the diameter d of the plurality of nano holes120is formed to 20 to 400 nm, the length t of the plurality of nano holes120may be 400 to 800 nm.

As the length t of the plurality of nano holes120increases, the light loss may increase. Accordingly, the maximum length of the plurality of nano holes120may be varied based on the required light efficiency. In other words, as shown inFIG. 11, the light efficiency may gradually decrease as the length of the plurality of nano holes120increases. Therefore, the maximum length of the plurality of nano holes120may be determined based on the required light efficiency.

In the exemplary embodiment of the present disclosure as described above, the plurality of nano holes120have a constant diameter d along the direction from the incident surface111of the lens body110toward the emitting surface112thereof. However, the present disclosure is not limited thereto, and the diameter d may gradually increase going from the incident surface111to the emitting surface112as shown inFIG. 12. However, the present disclosure is not limited thereto, and some of the plurality of nano holes120may have different diameters from others in the direction from the incident surface111to the emitting surface112depending on the degree of the phase delay of the light by the plurality of nano holes120.

A forming cycle w of the plurality of nano holes120(e.g., a pitch distance between the plurality of nano holes120) may be greater than the maximum value of the diameters d of the plurality of nano holes120. This is because, when the forming cycle w is less than the maximum value of the diameters d, the diameter d of the nano holes that may be formed in the lens body110is limited, so that the range of the phase delay of the light may be difficult to cover the entire 2π. In addition, the forming cycle w of the plurality of nano holes120may be 2 times or less of the maximum value of the diameters d of the plurality of nano holes120. This is because, when the forming cycle w exceeds twice the maximum value of the diameters d, a number of the nano holes causing the phase delay per unit area (e.g., an areal density) is decreased, and thus it may be difficult to achieve the required optical characteristics. Therefore, the forming cycle w of the plurality of nano holes120may be greater than d and less than 2*d.

For example, when the diameter d of the plurality of nano holes120is 20 to 1000 nm, the forming cycle w may be 200 to 1200 nm. When the optical lens100of the present disclosure is applied to a lighting device using visible light and the diameter d of the plurality of nano holes120is formed to 20 to 400 nm, the forming cycle w of the plurality of nano holes120may be 400 to 600 nm.

In the exemplary embodiment of the present disclosure as described above, the diameters d of the plurality of nano holes120may be uniform. However, the present disclosure is not limited thereto, and the diameters d of the plurality of nano holes120may be non-uniform depending on the degree of the phase delay by each nano hole. As shown inFIG. 13, when the diameters of adjacent nano holes are different from each other as d1and d2, and the maximum value of the diameters is d2, the forming cycle w may be greater than d2and less than 2*d2.

As described above, in the optical lens100of the present disclosure, the plurality of nano holes120may be directly formed on the lens body110. Therefore, compared to the case where the nano pins are individually formed in the shape of columns as in the related art, not only may the resistance to the external impact such as shock, vibration, and/or heat be improved, but also the manufacturing process may be simplified to reduce costs.

In other words, conventionally, since a plurality of nano pins are individually formed, they are more sensitive to shock, vibration, heat, or the like, and thus the probability of breakage or damage to each nano pin is relatively high. Conversely, in the exemplary embodiment of the present disclosure, due to the structure in which the plurality of nano holes120are formed in the lens body110itself, the resistance to the external environment may be improved.

In addition, the optical lens100of the present disclosure may experience minimal contraction or expansion due to a temperature change, and it is possible to correct chromatic aberration sufficiently even with a single optical lens. Therefore, since it is not necessary to use multiple lenses to correct chromatic aberration due to the temperature change, the structure may be more easily miniaturized.

The optical lens100ofFIGS. 2 to 4as described above is an example of implementing one optical characteristic. However, the present disclosure is not limited thereto. As shown inFIG. 14, when a plurality of groups G1-G4including at least one nano hole are formed in the lens body110and nano holes included in each group G1-G4are designed to have different optical characteristics, more than one optical characteristic may be obtained with a single optical lens. InFIG. 14, it is described as an example in which the plurality of groups G1-G4are formed in one lens body110. However, the present disclosure is not limited thereto, and each group may be formed on a separate lens body.

FIG. 15is a perspective view showing an optical lens according to another exemplary embodiment of the present disclosure, andFIG. 16is a side view showing the optical lens according to the another exemplary embodiment of the present disclosure. Referring toFIGS. 15 and 16, the optical device100according to the another exemplary embodiment of the present disclosure may include the lens body110, the plurality of nano holes120, and a support layer130. In the another exemplary embodiment of the present disclosure, the support layer130may support the lens body110to improve the rigidity of the lens body110, thereby preventing deformation, breakage, damage, or the like of the lens body110due to the external impacts.

InFIGS. 15 and 16, it is described as an example in which the support layer130is formed on the incident surface111of the lens body110. However, this configuration is only an example for helping the understanding of the present disclosure, and the present disclosure is not limited thereto. The support layer130may be formed on at least one of the incident surface111or the emitting surface112of the lens body110depending on a focal length of the optical lens100, a thickness of the support layer130, or the like.

The support layer130may be made of glass or a polymer material such as polymethyl methacrylate (PMMA) or polydimethylsiloane (PDMS), and may be made of a transparent material through which light may be transmitted. The support layer130may improve the assembling property when assembling the optical lens100that is manufactured in a small size. However, this configuration is only an example for helping the understanding of the present disclosure, and the present disclosure is not limited thereto. The support layer130may be omitted when sufficient assembly property is achieved by the optical lens100of the present disclosure without the support layer130.

FIG. 17is a schematic view showing a lighting device according to an exemplary embodiment of the present disclosure. Referring toFIG. 17, the lighting device200according to the exemplary embodiment of the present disclosure may include a light source unit210and an optical lens220. InFIG. 17, the optical lens220may be similar to the optical lens100of the exemplary embodiments as described above, and a detailed description thereof will be omitted.

In the exemplary embodiment of the present disclosure, the lighting device200may perform a function of a vehicle lamp to ensure that a forward view is secured when the vehicle is operating in low light conditions (e.g., at night or in a tunnel), or to inform the vehicles or pedestrians in the vicinity of the vehicle. When the lighting device200performs the function of the vehicle lamp, an appropriate beam pattern may be formed depending on the function.

The light source unit210may include at least one light source. The optical lens220may include a plurality of nano holes222that communicate between an incident surface221aand an emitting surface221bof a lens body221, so that the light generated from the light source unit210with a predetermined light irradiation angle may proceed in at least one direction by the optical lens220.

FIG. 17is an example of the case in which the light generated from the light source210with the predetermined light irradiation angle is converted to a substantially parallel light beam by the optical lens220and irradiated to the front of the vehicle to provide a forward illumination with a sufficient viewing distance. However, the present disclosure is not limited thereto. The light generated from the light source unit210may be formed to proceed in two or more directions depending on the degree of the phase delay of each of the plurality of nano holes222that are formed in the optical lens220to generate various beam patterns depending on the driving environment of the vehicle.

In addition, inFIG. 17, it is described as an example in which the light source unit210includes a single light source. However, the present disclosure is not limited thereto, and the light source unit210may include a plurality of light sources. In this case, the optical lens220may delay the phase of light generated from each of the plurality of light sources to form a suitable beam pattern.

As described above, the optical lenses100and220of the present disclosure and the lighting device200using the same may be implemented as meta structures, in which the plurality of nano holes120and222are formed in the lens bodies110and221. Therefore, the manufacturing process may be simplified, and the resistance to the external impact may be improved. In addition, since it is possible to realize various optical characteristics by the optical lenses100and220, miniaturization is possible.