Optical device and wearable device including the same

Abstract

According to one embodiment, an optical device includes: a light guide including a first surface and a second surface; and a diffractive structure disposed on any one of the first surface and the second surface. The diffractive structure includes a plurality of diffractive patterns spaced apart from each other, and includes a first metal layer disposed on one surface of the light guide portion and a second metal layer disposed on upper surfaces of the diffractive patterns.

Description

Technical Field

[0001] Embodiments relate to an optical device and a wearable device including the optical device. Background Art

[0002] With recent technological advancements, various types of wearable devices that can be worn on the human body are being used. Augmented reality devices (AR devices) are wearable devices in the form of glasses worn on the user's head. AR devices provide visual information through a display, thereby allowing the user to receive AR services.

[0003] AR refers to inserting three-dimensional images into the real environment and mixing real-world information with virtual images.

[0004] Real-world information may include information that the wearer does not need. In addition, real-world information may not have information that the wearer needs. AR devices combine the real world and the virtual world.

[0005] Unlike virtual reality devices that block the field of view, AR devices allow users to look forward when using them. In addition, a display similar to a wide screen can be located in front of the wearer's eyes, or the wearer can use various AR contents while wearing the AR device like conventional glasses. In addition, the user uses all space in a 360° direction centered on the user. Therefore, the AR device can support an extended reality experience that combines reality with AR content. In addition, the AR device is developed as a device with technology to replace smartphones because it provides a display optimized for the user's visual point when the user's hands are free.

[0006] The AR device includes an optical module that provides an AR image to the wearer. For example, the AR device can be an optical device composed of wearable glasses, and a projector that projects images onto the wearable glasses can be combined with it.

[0007] The light emitted from the projector is incident on the user's eyes through the optical device, so that the user can recognize the AR display.

[0008] On the other hand, the light emitted from the projector can be diffracted by the optical device and then can be incident on the user's eyes. To this end, the optical device can include a light guide and a diffraction structure.

[0009] The quality of the image recognized by the user varies depending on the diffraction efficiency of the diffraction structure. In addition, when the diffraction efficiency decreases at a set angle range, the visibility in the field of view at the set angle range may decrease.

[0010] Therefore, a light guide that can solve the above problems is needed. Summary of the Invention

[0011] Technical issues

[0012] Embodiments are directed to providing a light guide having improved diffraction efficiency at a wide viewing angle.

[0013] Technical Solution

[0014] According to an embodiment, an optical device includes: a light guiding portion, which includes a first surface and a second surface; and a diffraction structure, which is arranged on any one of the first surface and the second surface, wherein the diffraction structure includes a plurality of diffraction patterns spaced apart from each other and includes a first metal layer arranged on a surface of the light guiding portion and a second metal layer arranged on an upper surface of the diffraction pattern.

[0015] Light may be incident toward the first surface, and a first metal layer may be disposed on the first surface.

[0016] The diffraction structure may include a first diffraction structure provided on a region on which light is incident and a second diffraction structure provided on a region from which light is emitted.

[0017] The first metal layer and the second metal layer may be disposed to be spaced apart from each other.

[0018] A period can be defined, which is the distance over which the diffraction pattern repeats, and can be in the range of 300 nm to 600 nm.

[0019] A period can be defined, which is the distance over which the diffraction pattern repeats, and a fill factor can be defined, which is the ratio of the width of the diffraction pattern to the period, and can be in the range of 20% to 80%.

[0020] The height of the diffraction pattern may be in the range of 30 nm to 500 nm.

[0021] At least one of the thickness of the first metal layer and the thickness of the second metal layer may be in the range of 10 nm to 70 nm.

[0022] The height of the diffraction pattern may be greater than the thickness of the first metal layer by more than 10 nm.

[0023] The light may be transmitted through the diffraction pattern, or may be reflected from the diffraction pattern and incident into the light guiding portion.

[0024] The viewing angle of the light can be in the range of 20° to 40°.

[0025] The wearable device according to the embodiment includes a light source member that emits light and an optical device on which the light is incident.

[0026] Beneficial effects

[0027] An optical device according to an embodiment includes an optical device.

[0028] The optical device includes a light guiding portion and a diffractive structure.

[0029] The diffraction structure includes a plurality of diffraction patterns. In addition, a metal layer is provided on each of the upper surface of the diffraction structure and one surface of the light guide portion. The metal layers are provided to be spaced apart from each other.

[0030] Therefore, a plasma effect occurs in each metal layer. In addition, the plasma effects generated in each metal layer interact with each other.

[0031] Therefore, the optical device according to the embodiment can have uniform diffraction efficiency at a wide range of viewing angles. In addition, the optical device according to the embodiment can have high diffraction efficiency at a wide range of viewing angles. Specifically, the optical device according to the embodiment can have uniform and high diffraction efficiency at a viewing angle of 20° to 40°.

[0032] In addition, the period, fill factor, and height of the diffraction pattern according to the embodiment can be controlled. In addition, the thickness of the metal layer can be controlled.

[0033] Therefore, the optical device according to the embodiment may have uniform and high diffraction efficiency at viewing angles in a wide angular range. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a diagram illustrating a display device including a light guide according to an embodiment.

[0035] Figure 2 yes Figure 1 Magnified view of area A in FIG.

[0036] Figure 3 is a diagram for describing another position of a diffraction structure according to an embodiment.

[0037] Figure 4 1 is a diagram for explaining another shape of a diffraction pattern of a diffraction structure according to an embodiment.

[0038] Figure 5 is a diagram for describing the diffraction efficiency of an optical device according to a comparative example.

[0039] Figures 6 to 13 is a graph for describing the diffraction efficiency of the optical devices according to the embodiment and the comparative example.

[0040] Figure 14 and Figure 15 is a graph for describing the diffraction efficiency in another wavelength band of the optical device according to the embodiment.

[0041] Figure 16 and Figure 17 is a graph for describing the diffraction efficiency of an optical device according to a comparative example.

[0042] Figure 18 is a graph for describing diffraction efficiency according to the height of a diffraction structure according to an embodiment.

[0043] Figure 19 and Figure 20 is a graph for describing diffraction efficiency according to the height of a diffraction structure according to an embodiment.

[0044] Figure 21 and Figure 22 is a graph for describing diffraction efficiency according to a period of a diffraction structure according to an embodiment.

[0045] Figure 23 is a graph for describing diffraction efficiency according to arrangement of a metal layer of a diffraction structure according to an embodiment.

[0046] Figure 24 2 is a diagram illustrating a wearable device to which the optical device according to the embodiment is applied. DETAILED DESCRIPTION

[0047] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present disclosure is not limited to the partially described embodiments, but can be implemented in various different forms, and one or more components in the embodiments can be used by selectively combining or replacing them without departing from the scope of the technical spirit of the present disclosure.

[0048] In addition, the terms (including technical terms and scientific terms) used in the embodiments of the present disclosure may be interpreted as meanings that can be generally understood by technicians in the field to which the present disclosure belongs, and unless explicitly defined and described in detail, the meanings of commonly used terms (for example, terms defined in dictionaries) may be interpreted in consideration of the contextual meanings of the relevant technology.

[0049] In addition, the terms used in the embodiments of the present disclosure are used to describe the embodiments and are not intended to limit the present disclosure. In this specification, unless otherwise specified in a phrase, a singular form may include a plural form, and when described as "at least one (or one or more) of A, B, and C", it may include one or more of all possible combinations of A, B, and C.

[0050] In addition, terms such as first, second, A, B, (a), and (b) may be used to describe components of embodiments of the present disclosure. These terms are only used to distinguish one component from another, and the nature, order, sequence, etc. of the corresponding components are not limited by these terms.

[0051] In addition, when a specific component is described as being “connected,” “combined,” or “engaged” to another component, it may include a case where the specific component is directly connected, combined, or engaged to another component, and may also include a case where the specific component is “connected,” “combined,” or “engaged” to another component and there is another component between the specific component and the other component.

[0052] In addition, when a particular component is described as being formed or arranged "on (above) or below (under)" another component, "on (above)" or "below (under)" may include not only the case where the two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components.

[0053] In addition, when described as “upper” or “lower”, it may include not only a meaning based on an upward direction of one component but also a meaning based on a downward direction of one component.

[0054] Hereinafter, a light guide according to an embodiment will be described with reference to the accompanying drawings.

[0055] Figure 1 is a diagram illustrating a portion of a wearable device 1000 including a light guide according to an embodiment. The wearable device 1000 to be described below may be an augmented reality (AR) device.

[0056] Reference Figure 1 , the wearable device 1000 includes an optical device and a light source component 200. The optical device includes a light guiding portion 100 and a diffraction structure 400.

[0057] The light guiding portion 100 includes a first surface 1S and a second surface 2S opposite to the first surface 1S.

[0058] Light is incident on the first surface 1S. In addition, light is emitted from the first surface 1S. Specifically, the first light L1 emitted from the light source member 200 is emitted toward the first surface 1S of the light guide portion 100. Therefore, the first light L1 is incident into the light guide portion 100 through the first surface 1S.

[0059] First light L1 incident into the light guide 100 is totally reflected inside the light guide 100 and emitted through the first surface 1S to the outside of the light guide 100. Therefore, second light L2 emitted through the first surface 1S is transmitted to the user 300.

[0060] The light guide 100 includes a material that transmits light. The light guide 100 has a refractive index within a set range. Specifically, the light guide includes a material having a refractive index of 1.82 or greater. For example, the light guide includes glass having a refractive index of 1.82 to 2.

[0061] The light guide portion may have various shapes. For example, the light guide portion may have a circular or elliptical shape including a curved surface. Alternatively, the light guide portion may have a polygonal shape, for example, a triangle, a quadrilateral, etc.

[0062] The light guide guides light. For example, the light guide may be a waveguide.

[0063] The light source member 200 may include a projector. The first light L1 emitted from the light source member 200 may include image information. That is, the first light L1 incident on the light guide 100 includes image information. Therefore, the user 300 receives the image information emitted from the light source member 200 through the light guide 100.

[0064] The optical device includes a plurality of diffraction structures 400. Specifically, the optical device includes a first diffraction structure 410 and a second diffraction structure 420. The first diffraction structure 410 is disposed between the light guide 100 and the light source member 200. In other words, the first diffraction structure 410 is disposed in the region on which the first light L1 is incident. Furthermore, the second diffraction structure 420 is disposed between the light guide 100 and the user 300. In other words, the second diffraction structure 420 is disposed in the region from which the second light L2 is emitted.

[0065] Specifically, the first diffraction structure 410 is disposed along the optical path between the light guide portion 100 and the light source member 200. In addition, the second diffraction structure 420 is disposed along the optical path between the light guide portion 100 and the user 300.

[0066] Therefore, the first light L1 emitted from the light source member 200 is diffracted by the first diffraction structure 410 and incident into the light guide portion 100. In addition, the second light L2 emitted from the light guide portion 100 is diffracted by the second diffraction structure 420 and transmitted to the user 300.

[0067] Figure 2 and Figure 3 is a diagram for describing an optical device according to an embodiment. Figure 2 yes Figure 1 Magnified view of area A in FIG. Figure 3 is a diagram used to describe another position of the diffraction structure. Figure 2 and Figure 3 In the following, the first diffraction structure 410 will be mainly described. Figure 2 and Figure 3 The description can also be applied to the second diffraction structure 420 in the same manner.

[0068] Reference Figure 2The first diffraction structure 410 is disposed below the light guiding portion 100. Specifically, the first diffraction structure 410 may be disposed on the first surface 1S of the light guiding portion 100.

[0069] The first diffraction structure 410 includes a plurality of diffraction patterns P. That is, the first diffraction structure 410 is defined as a group of the plurality of diffraction patterns P.

[0070] The first light L1 emitted from the light source member 200 is diffracted by the diffraction pattern P. The diffracted light is incident into the light guide portion 100. That is, the diffraction pattern P may be a transmissive pattern.

[0071] A plurality of diffraction patterns P are provided on the first surface 1S. The plurality of diffraction patterns P protrude from the first surface 1S.

[0072] Alternatively, refer to Figure 3 , a plurality of diffraction patterns may be provided on the second surface 2S. The plurality of diffraction patterns P protrude from the second surface 2S.

[0073] The first light L1 emitted from the light source member 200 is diffracted by the diffraction pattern P. The diffracted light is incident into the light guide portion 100. That is, the diffraction pattern P may be a reflective pattern.

[0074] The diffraction pattern P can be formed into various shapes. Figure 2 and Figure 3 , the cross section of the diffraction pattern P may be formed as a rectangle. Alternatively, referring to Figure 4 The cross section of the diffraction pattern P can be formed into a trapezoidal shape with asymmetric left and right surfaces (see Figure 4 A). Alternatively, the cross section of the diffraction pattern P may be formed into a trapezoidal shape with left and right surfaces being symmetrical (see Figure 4 B).

[0075] The multiple diffraction patterns P are spaced apart from each other. Thus, the multiple diffraction patterns P have a period T, a fill factor FF, and a height H. The period T is defined as the distance between the multiple diffraction patterns P. The fill factor FF is defined as the ratio of the width of the diffraction pattern P to the period T. The height H is defined as the maximum distance from the first surface 1S to the top surface TS. Alternatively, the height H is defined as the maximum distance from the second surface 2S to the top surface TS.

[0076] The first diffraction structure 410 includes a metal layer 500. The metal layer 500 includes a first metal layer 510 and a second metal layer 520. The first metal layer 510 is disposed on the light guiding portion 100. Specifically, the first metal layer 510 is disposed on the first surface 1S.

[0077] The second metal layer 520 is disposed on the diffraction pattern P. Specifically, the second metal layer 520 is disposed on the upper surface TS of the diffraction pattern P.

[0078] Therefore, the first metal layer 510 and the second metal layer 520 may be spaced apart from each other. That is, the first metal layer 510 and the second metal layer 520 are spaced apart from each other by the height H of the diffraction pattern P.

[0079] Therefore, the plasmon effect based on the first metal layer 510 and the plasmon effect based on the second metal layer 520 may interact with each other, thereby improving the diffraction efficiency of the first diffraction structure 410 .

[0080] The first metal layer 510 and the second metal layer 520 may include gold (Au), silver (Ag), or aluminum (Al). The first metal layer 510 and the second metal layer 520 are formed with a thin film thickness. For example, the first metal layer 510 and the second metal layer 520 are set to a thickness in nanometers (nm).

[0081] The first diffraction structure 410 has improved diffraction efficiency through the first metal layer 510 and the second metal layer 520 .

[0082] Specifically, the first diffraction structure 410 has a plasmonic metasurface formed by a first metal layer 510 and a second metal layer 520. Therefore, by utilizing the plasmonic effect, improved diffraction efficiency can be achieved even at a wide viewing angle. Here, a wide viewing angle is an angle of 20° to 40°.

[0083] Plasmons are a phenomenon in which free electrons in a metal vibrate in unison due to the reaction between external light and the metal. This unison occurs because the energy of the incident light is transferred to the free electrons through resonance. Plasmons are particularly known as surface plasmons because they occur at the interface between metals and dielectrics. The closer the natural frequency of the free electrons in the metal resembles the frequency of the incident wave, the more efficient the energy transfer. The transferred energy is stored in the metal surface as a near-field.

[0084] The first diffraction structure 410 generates a plasmon effect through the first metal layer 510 and the second metal layer 520. Therefore, the diffraction efficiency of the first diffraction structure 410 is improved.

[0085] In order to have improved diffraction efficiency at a wide viewing angle, the period T, height H, fill factor FF and thickness of the metal layer in the first diffraction structure 410 are provided within set ranges.

[0086] Specifically, the period T of the diffraction pattern P may be greater than or equal to 300 nm. Specifically, the period T of the diffraction pattern P may be in the range of 300 nm to 600 nm.

[0087] In addition, the filling factor FF of the diffraction pattern P may be greater than 20%. Specifically, the filling factor FF of the diffraction pattern P may be in the range of 20% to 380%.

[0088] In addition, the height H of the diffraction pattern P may be greater than or equal to 30 nm. Specifically, the height H of the diffraction pattern P may be in the range of 30 nm to 500 nm.

[0089] In addition, at least one of the thickness T1 of the first metal layer 510 and the thickness T2 of the second metal layer 520 may be greater than 10 nm. Specifically, at least one of the thickness T1 of the first metal layer 510 and the thickness T2 of the second metal layer 520 may be within a range of 10 nm to 70 nm.

[0090] In addition, the height H of the diffraction pattern P may be greater than at least one of the thickness T1 of the first metal layer 510 and the thickness T2 of the second metal layer 520. For example, the height H of the diffraction pattern P may be greater than the thickness T1 of the first metal layer 510. Specifically, the height H of the diffraction pattern P may be greater than the thickness T1 of the first metal layer 510 by more than 10 nm.

[0091] Therefore, the first metal layer 510 and the second metal layer 520 can be prevented from contacting each other. Therefore, the diffraction efficiency of the first diffraction structure 410 can be improved.

[0092] Figure 5 is a graph for describing the diffraction efficiency when no metal layer is provided on the first diffraction structure 410 .

[0093] Reference Figure 5 (a) When the metal layer is not provided, the diffraction efficiency varies depending on the viewing angle. Specifically, excellent diffraction efficiency is obtained at a viewing angle of 5° to 25°. However, the diffraction efficiency decreases within the range of other viewing angles. Therefore, the diffraction efficiency decreases within a wide viewing angle.

[0094] In addition, refer to Figure 5 (b) When no metal layer is provided, the diffraction efficiency varies depending on the fill factor. Specifically, excellent diffraction efficiency is achieved at angles of 5° to 30°. However, the diffraction efficiency decreases within the range of other angles. Therefore, the diffraction efficiency decreases within a wide viewing angle.

[0095] Therefore, the optical device according to the embodiment includes multiple metal layers. The multiple metal layers are arranged at different positions. In addition, the multiple metal layers are spaced apart from each other. Therefore, the optical device according to the embodiment can have improved diffraction efficiency due to the interaction between the plasmon effect of the metal layers and the diffraction pattern.

[0096] Hereinafter, an optical device according to an embodiment will be described in detail through examples and comparative examples.

[0097] Example 1

[0098] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0099] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0100] The refractive index of the light guide is 1.5. The wavelength of the light is 528 nm. The period of the diffraction pattern is 415 nm. The fill factor of the diffraction pattern is 53.7%. The height of the diffraction pattern is 164 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 20 nm.

[0101] Subsequently, the diffraction efficiency of the optical device was measured.

[0102] Example 2

[0103] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0104] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0105] The refractive index of the light guide is 1.5. The wavelength of the light is 528 nm. The period of the diffraction pattern is 415 nm. The filling factor of the diffraction pattern is 25%. The height of the diffraction pattern is 60 nm. The metal layer comprises aluminum (Al). The thickness of the metal layer is 20 nm.

[0106] Subsequently, the diffraction efficiency of the optical device was measured.

[0107] Example 3

[0108] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0109] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0110] The refractive index of the light guide is 1.8. The wavelength of the light is 528 nm. The period of the diffraction pattern is 397 nm. The filling factor of the diffraction pattern is 28%. The height of the diffraction pattern is 70 nm. The metal layer comprises aluminum (Al). The thickness of the metal layer is 20 nm.

[0111] Subsequently, the diffraction efficiency of the optical device was measured.

[0112] Example 4

[0113] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0114] Then, light in the green wavelength range is emitted toward the optical device. The light is reflected from the diffraction pattern and is incident on the light guide portion.

[0115] The refractive index of the light guide is 1.8. The wavelength of the light is 528 nm. The period of the diffraction pattern is 397 nm. The filling factor of the diffraction pattern is 77%. The height of the diffraction pattern is 40 nm. The metal layer comprises aluminum (Al). The thickness of the metal layer is 20 nm.

[0116] Subsequently, the diffraction efficiency of the optical device was measured.

[0117] Example 5

[0118] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0119] Then, light in the blue wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0120] The refractive index of the light guide is 1.5. The wavelength of the light is 455 nm. The period of the diffraction pattern is 355 nm. The fill factor of the diffraction pattern is 38%. The height of the diffraction pattern is 80 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 20 nm.

[0121] Subsequently, the diffraction efficiency of the optical device was measured.

[0122] Example 6

[0123] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0124] Then, light in the red wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0125] The refractive index of the light guide is 1.5. The wavelength of the light is 621 nm. The period of the diffraction pattern is 480 nm. The fill factor of the diffraction pattern is 28%. The height of the diffraction pattern is 90 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 30 nm.

[0126] Subsequently, the diffraction efficiency of the optical device was measured.

[0127] Comparative Example 1

[0128] An optical device was manufactured in the same manner as in Example 1, except that no metal layer was provided on the diffraction pattern.

[0129] Subsequently, the diffraction efficiency of the optical device was measured.

[0130] Comparative Example 2

[0131] An optical device was manufactured in the same manner as in Example 2, except that no metal layer was provided on the diffraction pattern.

[0132] Subsequently, the diffraction efficiency of the optical device was measured.

[0133] Comparative Example 3

[0134] An optical device was manufactured in the same manner as in Example 3, except that no metal layer was provided on the diffraction pattern.

[0135] Subsequently, the diffraction efficiency of the optical device was measured.

[0136] Comparative Example 4

[0137] An optical device was manufactured in the same manner as in Example 4, except that no metal layer was provided on the diffraction pattern.

[0138] Subsequently, the diffraction efficiency of the optical device was measured.

[0139] Figure 6 and Figure 7 This graph shows the diffraction efficiency of the optical devices according to Example 1 and Comparative Example 1. The X-axis represents the incident angle of light. That is, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0140] Reference Figure 6The optical device according to Example 1 has a diffraction efficiency of 4% or more across all angles. Therefore, the optical device according to Example 1 has uniform diffraction efficiency across a wide angle range. Furthermore, the optical device according to Example 1 has high diffraction efficiency across a wide angle range.

[0141] On the other hand, refer to Figure 7 The optical device according to Comparative Example 1 has high diffraction efficiency only within the angular range of 0° to ±4°. Furthermore, the optical device has low diffraction efficiency within other angular ranges. In other words, the optical device according to Comparative Example 1 has high diffraction efficiency only within a narrow angular range.

[0142] Figure 8 and Figure 9 This graph shows the diffraction efficiency of the optical devices according to Example 2 and Comparative Example 2. The X-axis represents the incident angle of light. That is, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0143] Reference Figure 8 , the optical device according to Example 2 has a diffraction efficiency of 5% or more in all angle ranges. Therefore, the optical device according to Example 2 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 2 has high diffraction efficiency in a wide angle range.

[0144] On the other hand, refer to Figure 9 , the optical device according to Comparative Example 2 has high diffraction efficiency only within the angular range of 0° to -13°. Furthermore, the optical device has low diffraction efficiency within other angular ranges. In other words, the optical device according to Comparative Example 2 has high diffraction efficiency only within a narrow angular range.

[0145] Figure 10 and Figure 11 This graph shows the diffraction efficiency of the optical devices according to Example 3 and Comparative Example 3. The X-axis represents the incident angle of light. In other words, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0146] Reference Figure 10 The optical device according to Example 3 has a diffraction efficiency of 20% or more in all angle ranges. Therefore, the optical device according to Example 3 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 3 has high diffraction efficiency in a wide angle range.

[0147] On the other hand, refer to Figure 11The optical device according to Comparative Example 3 has high diffraction efficiency only within the angular range of 0° to -13°. Furthermore, the optical device has low diffraction efficiency within other angular ranges. In other words, the optical device according to Comparative Example 3 has high diffraction efficiency only within a narrow angular range.

[0148] Figure 12 and Figure 13 This graph shows the diffraction efficiency of the optical devices according to Example 4 and Comparative Example 4. The X-axis represents the incident angle of light. In other words, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0149] Reference Figure 12 The optical device according to Example 4 has a diffraction efficiency of 25% or more in all angle ranges. Therefore, the optical device according to Example 4 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 4 has high diffraction efficiency in a wide angle range.

[0150] On the other hand, refer to Figure 13 The optical device according to Comparative Example 3 has high diffraction efficiency only within the angular range of 0° to ±4°. Furthermore, the optical device has low diffraction efficiency within other angular ranges. In other words, the optical device according to Comparative Example 4 has high diffraction efficiency only within a narrow angular range.

[0151] Figure 14 and Figure 15 This graph shows the diffraction efficiency of optical devices according to Examples 5 and 6. The X-axis represents the incident angle of light. That is, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Furthermore, the Y-axis represents the diffraction efficiency.

[0152] Reference Figure 14 The optical device according to Example 5 has a diffraction efficiency of 6% or more in all angle ranges. Therefore, the optical device according to Example 5 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 5 has high diffraction efficiency in a wide angle range.

[0153] Reference Figure 15 The optical device according to Example 6 has a diffraction efficiency of 20% or more in all angle ranges. Therefore, the optical device according to Example 6 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 6 has high diffraction efficiency in a wide angle range.

[0154] Referring to Examples 1 to 6, the optical device has improved diffraction efficiency by the metal layer.The optical device includes a first metal layer disposed on one surface of a light guide portion and a second metal layer disposed on an upper surface of a diffraction pattern.

[0155] The plasmon effect of the first metal layer and the plasmon effect of the second metal layer interact with each other. Therefore, the optical device according to the embodiment can have improved diffraction efficiency.

[0156] Example 7

[0157] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0158] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0159] The refractive index of the light guide is 1.5. The wavelength of the light is 528 nm. The period of the diffraction pattern is 420 nm. The fill factor of the diffraction pattern is 20%. The height of the diffraction pattern is 100 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 80 nm.

[0160] Subsequently, the diffraction efficiency of the optical device was measured.

[0161] Comparative Example 5

[0162] An optical device was manufactured in the same manner as in Example 7, except that the thickness of the metal layer was 90 nm.

[0163] Subsequently, the diffraction efficiency of the optical device was measured.

[0164] Figure 16 and Figure 17 This graph shows the diffraction efficiency of the optical devices according to Example 7 and Comparative Example 5. The X-axis represents the incident angle of light. In other words, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0165] Reference Figure 16 The optical device according to Example 7 has a diffraction efficiency of 7% or more in all angle ranges. Therefore, the optical device according to Example 7 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 7 has high diffraction efficiency in a wide angle range.

[0166] Reference Figure 17 , the optical device according to Comparative Example 5 has a diffraction efficiency of 0.8% or more in all angle ranges. The optical device according to Comparative Example 5 has uniform diffraction efficiency in a wide angle range. However, the optical device according to Comparative Example 5 has low diffraction efficiency.

[0167] With reference to Example 7 and Comparative Example 5, the diffraction efficiency of the optical device according to the embodiment is correlated with the thickness of the metal layer. Specifically, when the thickness of the metal layer is within the range of 10 nm to 70 nm, the optical device has high and uniform diffraction efficiency over a wide angle range. On the other hand, when the thickness of the metal layer exceeds this range, the optical device has uniform diffraction efficiency over a wide angle range; however, the optical device has low diffraction efficiency.

[0168] Example 8

[0169] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0170] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0171] The refractive index of the light guide is 1.5. The wavelength of the light is 528 nm. The period of the diffraction pattern is 510 nm. The fill factor of the diffraction pattern is 30%. The height of the diffraction pattern is 275 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 30 nm.

[0172] Subsequently, the diffraction efficiency of the optical device was measured.

[0173] Example 9

[0174] A plurality of diffraction patterns are provided on the light guide portion. In addition, a metal layer is provided on each of the upper surface of the diffraction pattern and one surface of the light guide portion. Thus, an optical device is manufactured.

[0175] Then, light in the green wavelength range is emitted toward the optical device, and the light passes through the diffraction pattern and enters the light guide portion.

[0176] The refractive index of the light guide is 1.5. The wavelength of the light is 528 nm. The period of the diffraction pattern is 420 nm. The fill factor of the diffraction pattern is 50%. The height of the diffraction pattern is 390 nm. The metal layer contains silver (Ag). The thickness of the metal layer is 30 nm.

[0177] Subsequently, the diffraction efficiency of the optical device was measured.

[0178] Figure 18 This graph shows the diffraction efficiency as a function of the height of the diffraction pattern. The X-axis represents the incident angle of light. In other words, 0° on the X-axis represents the optical axis. In other words, the X-axis represents the viewing angle range. Furthermore, the Y-axis represents the height of the diffraction pattern.

[0179] Figure 19 and Figure 20 This graph shows the diffraction efficiency of the optical devices according to Example 8 and Comparative Example 9. The X-axis represents the incident angle of light. That is, 0° on the X-axis refers to the optical axis. In other words, the X-axis represents the viewing angle range. Additionally, the Y-axis represents the diffraction efficiency.

[0180] Reference Figure 19 The optical device according to Example 8 has a diffraction efficiency of 6% or more in all angle ranges. Therefore, the optical device according to Example 8 has uniform diffraction efficiency in a wide angle range. In addition, the optical device according to Example 8 has high diffraction efficiency in a wide angle range.

[0181] Reference Figure 20 The optical device according to Example 9 has a diffraction efficiency of 20% or more across all angles. Therefore, the optical device according to Example 9 has uniform diffraction efficiency across a wide angle range. Furthermore, the optical device according to Example 9 has high diffraction efficiency across a wide angle range.

[0182] Reference Figures 18 to 20 The diffraction efficiency of an optical device is correlated with the height of the diffraction pattern. Specifically, when the diffraction pattern height is within the range of 30 nm to 500 nm, the optical device exhibits high and uniform diffraction efficiency over a wide angle range. On the other hand, when the diffraction pattern height exceeds this range, the optical device exhibits low diffraction efficiency.

[0183] Figure 21 and Figure 22 This is a graph for comparing the diffraction efficiency of optical devices according to the period of the diffraction pattern.

[0184] Figure 21 (a) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 455 nm. Figure 21 (b) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 528 nm. Figure 21 (c) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 621 nm.

[0185] Figure 22 (a) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 455 nm. Figure 22 (b) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 528 nm. Figure 22 (c) shows the diffraction efficiency of the optical device when the period of the diffraction pattern is 621 nm.

[0186] Reference Figure 21 and Figure 22, the diffraction efficiency of the optical device is related to the period of the diffraction pattern. That is, when the period of the diffraction pattern is in the range of 300nm to 600nm, the optical device has a high and uniform diffraction efficiency within a wide angle range of viewing angles. On the other hand, when the period of the diffraction pattern exceeds the above range (see Figure 21 (c) and Figure 22 (c)), the optical device has low diffraction efficiency.

[0187] Figure 23 is a graph for comparing diffraction efficiencies of optical devices according to arrangements of metal layers.

[0188] Figure 23 (a) shows a case where the optical device includes a first metal layer and a second metal layer. Figure 23 (b) shows the case where the optical device includes only the second metal layer.

[0189] Reference Figure 23 (a) forms a blue region with low reflectivity within a narrow wavelength range. The blue region is the region where light is diffracted by the diffraction pattern and incident on the light guide. Therefore, when the optical device includes the first and second metal layers, the optical device can have uniform diffraction efficiency over a wide angle.

[0190] On the other hand, refer to Figure 23 (b) , a blue region with low reflectivity is formed in a region of a wide wavelength range. Therefore, when the optical device includes only the second metal layer, the optical device cannot have uniform diffraction efficiency at a wide viewing angle.

[0191] Therefore, the optical device according to the embodiment may have uniform and high diffraction efficiency through the first metal layer and the second metal layer provided at different positions.

[0192] In the following, reference will be made to Figure 24 An example of a display device including an optical device according to an embodiment is described.

[0193] Reference Figure 24 The optical device according to the embodiment can be applied to a wearable display device. Specifically, the optical device according to the embodiment can be applied to a wearable display device worn on the head or ear of a human body.

[0194] For example, the display device 2000 may be an AR device.

[0195] The display device 2000 includes a wearable unit 2100 and a display unit 2200 .

[0196] The wearable unit 2100 can extend in one direction. The wearable unit 2100 can be worn on the user's body. For example, the wearable unit 2100 can be worn on the user's head or ear, so that the display device 2000 can be fixed to the user's body. For example, the wearable unit 2100 can be a glasses frame in a wearable display device.

[0197] The light source member 200 is provided on the wearable unit 2100. The light source member 200 emits light toward the display unit 2200. Specifically, the light source member 200 emits light including image information toward the display unit 2200. For example, the light source member 200 may be a projector.

[0198] The display unit 2200 may be the above-mentioned optical device. Alternatively, the display unit 2200 may be AR glasses including the optical device.

[0199] Therefore, the user may receive light including image information emitted from the light source member 200 through the display unit 2200. Therefore, the user may recognize virtual reality and AR of real reality through the optical device.

[0200] The features, structures, effects, etc. described in the above embodiments are included in at least one embodiment and are not necessarily limited to one embodiment. In addition, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified and implemented in other embodiments by those skilled in the art to which the embodiment belongs. Therefore, descriptions related to such combinations and modifications should be interpreted as being included within the scope of the present invention.

[0201] In addition, although the embodiments are mainly described above, these embodiments are merely exemplary and do not limit the present invention, and those skilled in the art to which the present invention belongs will appreciate that various modifications and applications not illustrated above can be made without departing from the essential features of the embodiments. For example, the various components specifically shown in the embodiments can be implemented by modifications thereof. In addition, differences associated with these modifications and applications should be interpreted as being included within the scope of the present invention as defined in the appended claims.

Claims

1. An optical device comprising: a light guide, the light guide comprising a first surface and a second surface; as well as a diffraction structure, wherein the diffraction structure is provided on either the first surface or the second surface, Wherein, the diffraction structure includes a plurality of diffraction patterns spaced apart from each other, and The diffraction structure includes a first metal layer disposed on one surface of the light guide portion and a second metal layer disposed on an upper surface of the diffraction pattern.

2. The optical device according to claim 1, wherein light is incident toward the first surface, and The first metal layer is disposed on the first surface.

3. The optical device according to claim 1, wherein The diffraction structure includes a first diffraction structure provided on a region where light is incident and a second diffraction structure provided on a region where light is emitted.

4. The optical device according to claim 1, wherein The first metal layer and the second metal layer are disposed to be spaced apart from each other.

5. The optical device according to claim 1, wherein is defined as having a period, which is the distance over which the diffraction pattern repeats, and The period is in the range of 300 nm to 600 nm.

6. The optical device according to claim 1, wherein A period is defined, which is the distance over which the diffraction pattern repeats, A filling factor is defined, which is the ratio of the width of the diffraction pattern to the period, and The fill factor is in the range of 20% to 80%.

7. The optical device according to claim 1, wherein The height of the diffraction pattern is in the range of 30 nm to 500 nm.

8. The optical device according to claim 1, wherein At least one of the thickness of the first metal layer and the thickness of the second metal layer is in a range of 10 nm to 70 nm.

9. The optical device according to claim 8, wherein The height of the diffraction pattern is greater than the thickness of the first metal layer by more than 10 nm.

10. The optical device according to claim 2, wherein The light is transmitted through the diffraction pattern, or is reflected from the diffraction pattern and incident into the light guiding portion.

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