KR20210059594A - Device for enlarging an exit pupil area and display including the same - Google Patents

Abstract

Provided is an exit pupil expander and a display including the same. The exit pupil expander includes: a diffraction grating configured to output a plurality of diffracted light beams of a plurality of diffraction orders by diffracting an incident light beam; and a waveguide provided on the diffraction grating and configured to form the exit pupil expander and exit pupil orders the plurality of diffracted light beams output from the diffraction grating. The present invention provides a compact, universal exit pupil expander with low energy loss from light.

Description

An exit door expander and a display including the same {DEVICE FOR ENLARGING AN EXIT PUPIL AREA AND DISPLAY INCLUDING THE SAME}

Disclosed embodiments relate to an optical device capable of expanding an eye box of a visual optical device and a display including the same.

Visual optical devices such as augmented reality devices, eyepieces, and lenses of optical devices (microscopes, telescopes, sights, etc.) are being actively improved. The most important characteristic parameters of such visual optics are the size of the field of view (FoV) and the size of the eye box. According to prior art analysis, a wide field of view (e.g., 60 minutes) is formed in a visual optics device, forming the required image quality or resolution (e.g., not greater than the limiting angle of the resolution of the eye, equal to 1 arc minute). It is very difficult to provide both a degree or more) and a large eye box (eg, 3 mm or more) at the same time. The common device known to extend the eye box is not universal because complex elements are used. Conversely, it is necessary to separately design a device for extending the eye box for each visual optical device.

The exit pupil expander with a wide field of view disclosed in US 8508848 B2 (published August 15, 2013) is known in the prior art. The exit pupil expander includes a waveguide, and radiation enters the waveguide through a diffractive element, travels inside the waveguide, and may be emitted through the diffractive element. The above-described exit pupil expander can increase the field of view without a material having a high refractive index. However, it has a complex structure where the width of the field of view is small (limited value of the horizontal size of the field of view), and the overall dimension is large. In addition, this type of exit pupil expander can cause significant energy losses because light propagates along long distances in the waveguide. In such a device, the diffraction efficiency, uniformity, and brightness of the resulting image may be limited because several diffractive elements are used to enter and emit light.

The substrate-guided optical beam expander disclosed in US 6829095 B2 (published May 16, 2001) is known in the prior art, and the expander is a waveguide device, and the light is displayed in the field of view using a translucent mirror. Can be. The size of the exit pupil is related to the geometrical parameters of the dilator, in particular the thickness of the waveguide and the number of mirror elements. The disadvantage of such a device is that the waveguide has a fairly large thickness, so that the expander has a large overall dimension and the design is complex. In addition, even if such a device is used, a sufficient field of view cannot be obtained.

It is possible to provide an exit pupil expander capable of expanding an eye box capable of providing a large area of an exit pupil while maintaining a wide field of view, high diffraction efficiency, image uniformity and brightness of a visual optical device.

Energy loss from incident light is small, and it is possible to provide a compact, universal exit pupil expander.

It is also possible to provide an exit pupil expander that can be easily integrated into any visual optics device.

According to one type, the exit pupil expander for expanding the exit pupil of the visual optical device comprises: a diffraction grating for diffracting incident light to output a plurality of diffracted lights having different diffraction orders; And an exit pupil arranged on the diffraction grating, using a first diffracted light of the plurality of diffracted lights output from the diffraction grating, and an exit pupil order using a second diffracted light of the plurality of diffracted lights. It includes; waveguide forming a.

In addition, the waveguide may form the exit pupil by outputting the first diffracted light output from the diffraction grating without total reflection.

In addition, the waveguide may form at least one exit pupil order by totally internally reflecting the second diffracted light output from the diffraction grating at least once and then outputting it.

In addition, the waveguide reflects the second diffracted light internally and re-enters the diffraction grating, the diffraction grating diffracts the second diffracted light and outputs a plurality of diffracted light, and the waveguide diffracts the second diffracted light The exit pupil order is formed by outputting some of the diffracted light of the plurality of diffracted light according to the result, and the remaining diffracted light of the plurality of diffracted light may be totally reflected and re-incident to the diffraction grating.

In addition, the waveguide may include a first surface facing the diffraction grating and a second surface facing the first surface to output the first diffracted light to the outside.

In addition, the waveguide may additionally form the exit pupil order until all of the diffracted light incident on the second surface is totally reflected.

In addition, the number of exit pupil orders may be proportional to the number of times that some of the diffracted light incident on the second surface of the waveguide are transmitted.

In addition, the spacing between the exit pupil orders may be proportional to the thickness of the guiding tube.

In addition, the spacing between the exit pupil orders may be in inverse proportion to the refractive index of the guiding tube.

In addition, the first diffracted light is diffracted light having a diffraction order of "0", and the first diffracted light includes at least one of diffracted light having a diffraction order of "+1" and diffraction light having a diffraction order of "-1". Can include.

In addition, the waveguide may form a first exit pupil order using diffracted light having the "+1" diffraction order, and form a second exit pupil order using diffracted light having the "-1" diffraction order. I can.

In addition, the waveguide may have the first exit pupil order and the second exit pupil order in different directions with the exit pupil interposed therebetween.

In addition, the diffraction grating may diffract light incident below the aperture angle.

In addition, the opening angle may be greater than or equal to the viewing angle of the visual optical device.

Further, a second waveguide disposed on the diffraction grating and totally reflecting the light output from the diffraction grating may be further included.

In addition, the diffraction grating may be disposed between the first waveguide and the second waveguide.

In addition, the diffraction grating includes a first diffraction region for diffracting light incident below a first aperture angle and a second diffraction region for diffracting light incident at a second aperture angle greater than or equal to the first aperture angle, The waveguide may include: a first waveguide forming an exit pupil order by using the diffracted light output to the first diffraction region; And a second waveguide for forming an exit pupil order by using the diffracted light output from the second diffraction region.

In addition, the diffraction grating, the first waveguide, and the second waveguide may be sequentially arranged based on a path of the light.

In addition, the waveguide may have a curved shape.

In addition, the diffraction grating may include a Bragg diffraction grating.

The display according to an exemplary embodiment includes a visual optical device that emits a λ at a specific viewing angle, and the above-described dynamic expander for expanding an exit pupil area of the visual optical device.

In addition, the display may be a near-eye display.

The disclosed exit pupil expander is universal and can have high diffraction efficiency if it has a compact and slim design.

The eye box can be extended while maintaining the field of view of the visual optics.

The image formed in the exit pupil can ensure uniformity and brightness.

It can also be applied to images using multispectral light.

1 is a diagram illustrating a telecentric ray path in an object space.
2A is a view showing an exit expander for expanding an eye box according to an embodiment.
2B is a view showing the propagation of light in an exit pupil expander extending an eye box according to an exemplary embodiment.
2C is a diagram illustrating an example of using an exit pupil expander in a visual optical device according to an exemplary embodiment.
2D is a diagram illustrating an exit pupil expander operating in a reflection mode according to an exemplary embodiment.
3 shows a space diagram of a display using an exit pupil expander according to an embodiment.
4A is a view showing a coupler and an exit pupil expander operating in a transmission mode according to an embodiment.
4B is a diagram illustrating a relationship between a coupler operating in a reflection mode and an exit pupil expander according to an exemplary embodiment.
5 is a diagram conceptually showing an exit pupil expander including a one-dimensional diffraction grating according to an embodiment.
6 is a conceptual diagram illustrating an exit pupil expander including a two-dimensional diffraction grating according to an exemplary embodiment.
7 is a view showing an exit pupil expander according to another embodiment.
8A is a diagram illustrating an eye box including a plurality of discretely distributed exit orders.
8B is a diagram illustrating an exit pupil order formed by an exit pupil expander according to an exemplary embodiment.
9 is a view showing a planar exit exit expander forming a spot according to an embodiment.
10 is a view showing a curved exit exit expander according to an embodiment.
11 is a diagram illustrating an exit pupil expander including a plurality of waveguides according to another exemplary embodiment.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. The described embodiments are merely exemplary, and various modifications are possible from these embodiments. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description.

Hereinafter, what is described as "top" or "top" may include not only those directly above by contact, but also those that are above non-contact.

Terms such as first and second may be used to describe various elements, but are used only for the purpose of distinguishing one element from other elements. These terms are not intended to limit differences in materials or structures of components.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

The use of the term "above" and similar reference terms may correspond to both the singular and the plural.

The steps constituting the method may be performed in any suitable order unless there is a clear statement that the steps constituting the method should be performed in the order described. In addition, the use of all exemplary terms (eg, etc.) is merely for describing technical ideas in detail, and the scope of the rights is not limited by these terms unless limited by claims.

One diffraction grating, which is a diffractive optical element (DOE) or a holographic optical element (HOE) used for incidence or emission of light to solve the aforementioned problems and achieve technical results. A miniature device may be proposed that expands the eye box (also referred to as the exit pupil region) on the basis of the and waveguide.

The proposed device can be used to expand the eye box of a visual optical device, for example the eyepiece of an optical instrument. As is known, the eyepiece of an optical device is an element of the optical device facing the viewer's eye, and the eyepiece is an optical device designed to view the image formed by the device's lens or housing (viewfinder, range finder, binoculars, microscope, Telescope, etc.).

The proposed device for expanding the eye box can be applied to an augmented reality device (AR) with an image combiner that combines an environment image and an image formed by an internal display using a visual optical device or HOE/DOE.

The device proposed to expand the eye box (hereinafter referred to as'injection-dong expander') can be compact and universal. Here, compactness and universality are determined by using only a diffraction grating, which is one element, for the incidence and emission of light, and the waveguide used in the proposed device does not have to be of high quality.

The proposed exit dilator may have a small overall dimension. That is, the proposed device does not change the overall dimensions of the visual optical device, and can be used in a variety of optical devices.

The exit pupil of the visual optics is the area in which the viewer sees the image. In other words, the exit pupil is a paraxial image of the aperture diaphragm in image space, and this image can be formed by the next part of the visual optics in the direct course of the light beam. This term is well established in the field of optics. The main characteristic of the exit pupil of the visual optics is that the entire image field is at any point in the optics.

Increasing (expanding) the exit pupil means that the dimension (or number) of the exit pupil is increased without increasing the longitudinal dimensions of the visual optics. Classical optics can increase the size of the exit pupil, but the longitudinal size of the visual optics must also increase at the same time. The use of the waveguide optics can increase the dimension of the exit pupil without significantly increasing the size of the visual optics, due to multiple reflections of radiation beams inside the waveguide.

The eye box is an area that the pupil of the human eye can access from an arbitrary position of the eye pupil (when the eye pupil is displaced), and is also referred to as an exit pupil region including the exit pupil.

The size of the field of view is the angular space visible from the pupil and the fixed position of the fixed head. When the size of the field of view is large, the eye can see most of the object space. However, if the pupil of the eye is displaced by, for example, a few millimeters laterally, the field of view may be blocked and the size of the field of view may be reduced. This is because the eye box of the visual optics device is small, and when the pupil of the eye is displaced, the eye box does not perfectly coincide with the pupil of the eye or does not coincide at all.

Diffraction efficiency is a characteristic of a diffraction grating, and its unit is measured in percent or decimal fraction, and is the ratio of the energy contained in one of the diffraction orders to the energy incident on the diffraction grating.

1 is a diagram illustrating a telecentric ray path in an object space. As shown in FIG. 1, light emitted from a general visual optical device may form an exit pupil.

The size of the field of view FoV of the visual optical device 100 may be determined according to Equation 1 below.

[Equation 1]

Here, S is the size of the object (unit: mm), F is the focal length (unit: mm) of the lens included in the visual optical device 100, and FoV is the size of the field of view (unit: degree).

The size E of the exit pupil of the visual optical device 100 may be determined by Equation 2 below.

[Equation 2]

Here, E is the size of the exit pupil (mm), Le is the eye-relief distance (mm) from the visual optical device 100 to the pupil 1a of the eye 1, and D is the visual optical device. It is the aperture (mm) of the clear lens included in (100).

As shown in Equations 1 and 2, when the exit pupil expander according to an embodiment is not applied to the visual optical device 100, the size E of the eye box is limited by the field of view FoV, The field of view (FoV) may be limited by the focal length (F) of the visual optical device 100 and the size (S) of the object. The larger the space (ie, object) area of the object that the user wants to see, the larger the field of view (FoV) should be. On the other hand, the focal length F of the lenses included in the visual optical device 100 should be smaller as devices such as augmented reality glasses become smaller.

According to Equations 1 and 2, in general, there is an inversely proportional relationship between the size of the field of view (FOV) and the size of the eye box (E). In a typical visual optics device 100, it is difficult to increase both the size of the field of view (FOV) and the size of the eye box (E) without using additional elements. The device for expanding the eye box according to one embodiment is universal and compact.

2A is a view showing an exit expander for expanding an eye box according to an embodiment. 2A, the exit pupil expander 200 may include a waveguide 230 and a diffraction grating 210. When the exit pupil expander 200 uses the diffraction grating 210, the diffraction order exists only in the waveguide 230, and the diffraction order does not exist in free space.

The diffraction grating 210 may be designed for a specific angle of incidence of light incident on the diffraction grating 210. The angle of incidence may be determined by an aperture angle, that is, a viewing angle of the optical optical device 100. In other words, the light may be emitted from the optical optical device 100 at a specific angle with respect to the optical axis, and may be incident on the diffraction grating 210 at the same angle as the specific angle.

The diffraction grating 210 of the exit pupil expander 200 may be designed so that incident light is diffracted by three diffraction orders of “0”, “+1” and “-1”. And this diffraction order may propagate into the waveguide 230

The period of the diffraction grating 210 that satisfies the above conditions is shown in Equation 3 below.

[Equation 3]

Here, n1 is the refractive index of the medium in front of the exit pupil expander 200, for example, the refractive index of air, n2 is the refractive index of the waveguide 230, M is the number of diffraction orders, and d is the period of the grating.

Is the incident angle of light, 1 is the incident angle of light incident on the diffraction grating 210 from the air, and 2 is a diffraction angle, that is, the angle of light traveling from the diffraction grating 210 into the waveguide 230 of the diffraction order M to be.

는 회절 격자(210)에 입사하는 광의 파장이며;

Is the wavelength of light incident on the diffraction grating 210;

T is the frequency of the diffraction grating 210 and may be expressed as an reciprocal of a period, that is, T = 1/d. If d is expressed in mm, T can be expressed in dash/mm. .

The diffraction grating 210 may be designed to expand the eye box according to Equation 3. Determination of the parameters of the diffraction grating 210 may vary depending on a specific function that the diffraction grating 210 must perform. The parameters of the diffraction grating 210 may be a period (constant or variable) of the diffraction grating 210, a relief depth, a type of profile (stroke), a direction of a stroke, and the like. Here, the specific function to be performed by the diffraction grating 210 is to expand the eye box.

The parameters of the diffraction grating 210 may vary depending on the following.

-Incident angle of light incident on the diffraction grating 210 from the visual optical device 100,

-The material of the waveguide 230 where the diffraction grating 210 is located,

-The size of the eye box to be expanded

The function of the diffraction grating 210 can be determined by the following.

When the diffraction grating 210 is in the hologram recording mode, the function of the diffraction grating 210 may be determined by the spatial arrangement of the recording sources with respect to each other and the ratio of the radiated power of the recording sources.

When the diffraction grating 210 is in the lithographic recording mode, the function of the diffraction grating 210 may be determined by the structure of the diffraction grating 210 determined by modeling and calculation.

According to preliminary theory and computer modeling, it can be demonstrated that the parameters of the diffraction grating 210 and waveguide 230 match so that a combination of these elements can act to expand the eye box.

That is, in the exit pupil expander 200, the parameters of the diffraction grating 210 may be designed such that there are only three diffraction orders of “0”, “+1” and “-1”. Among these diffraction orders, diffracted light having a diffraction order excluding the "0" diffraction order may be reflected at least once or more from the surface of the waveguide 230 under conditions of total internal reflection (TIR) to proceed into the waveguide 230. . The diffracted light of the 0th diffraction order may be refracted at the boundary between the waveguide 230 and the air and may be emitted from the exit pupil expander 200 without total internal reflection.

The core element of the exit pupil expander 200 is the waveguide 230, and the waveguide 230 allows the incident light to operate in the waveguide 230 mode. The waveguide 230 mode refers to "+1" and "-1" diffraction so that when diffracted light of "+1" and "-1" diffraction orders is incident on the interface between the waveguide 230 and air, total reflection can be obtained. It may mean that the angle of incidence for the order of diffracted light is equal to or greater than the total reflection angle. There is a certain relationship between the parameters of the waveguide 230 and the function of the waveguide 230.

In a preferred embodiment, the thickness of the waveguide 230 is preferably thin so that the light emitted from the waveguide 230 is uniform, and then the light may be uniform even in the eye box, which is an extended area of the exit pupil. For example, the thickness of the waveguide 230 may be about 3 mm or less.

Therefore, in order to obtain the characteristic of expanding the eye box, the parameters of the waveguide 230 and the diffraction grating 210 must be matched to obtain a new characteristic that expands the range of the exit pupil.

Methods of manufacturing the diffraction grating 210 are well known in the art. For example, the relief diffraction gratings 210 may be manufactured by etching through mask or nano-imprinting, and the holographic diffraction grating 210 may be recorded by an interference pattern or the like.

The fabricated or recorded diffraction grating 210 can be applied to both the planar waveguide 230 or the non-planar waveguide 230. The diffraction grating 210 can generally be applied on the waveguide 230 when manufacturing the exit pupil expander 200. In order to obtain the effect of increasing the light rays incident on the exit pupil expander 200 without changing the characteristics of the light rays, it is preferable that the parameters of the diffraction grating 210 and the waveguide 230 match during the manufacturing process.

Forming the diffraction grating 210 on the waveguide 230 may be performed on a substrate coated with a photosensitive material. For example, the substrate may essentially perform the function of the waveguide 230, and the diffraction grating 210 may be formed on the substrate with a material and thickness capable of expanding the eye box. The parameters of the substrate may match those of the diffraction grating 210.

Alternatively, after forming the diffraction grating 210 on the photoresist material, the diffraction grating 210 is copied and transferred to the photopolymer to form the thin film type diffraction grating 210. Further, the thin film type diffraction grating 210 can be applied to the waveguide 230 in any known manner. In this case, the parameters of the waveguide 230 and the parameters of the diffraction grating 210 must match as described above, which can expand the eye box.

During manufacture, the exit pupil expander 200 may be designed to correspond to a specific incident angle determined by an aperture angle of the visual optical device 100. Even if the opening angle of the visual optical device 100 is not the same as the opening angle of the exit dilator 200, if the opening angle of the visual optical device 100 is less than the opening angle of the exit dilator 200, the exit dilator 200 ) Can be integrated into the above-described visual optical device 100 to operate accurately. This means the universality of the exit pupil expander 200 according to an embodiment for expanding the eye box. That is, it means that the exit pupil expander 200 has an angular range capable of accurately operating, and the above-described range may be the size of the exit opening angle of the visual optical device 100.

For example, the exit pupil dilator 200 may be designed for a visual optics device 100 having an opening angle (ie, viewing angle) of 60°. The exit pupil expander 200 may also be used for the visual optical device 100 having an opening angle (viewing angle) of less than 60° (eg, 40°). However, when the visual optical device 100 has an opening angle (viewing angle) greater than 60°, the exit pupil expander 200 having an opening angle of 60° malfunctions, so the visual optical device 100 Cannot be used.

FIG. 2B is a view showing the propagation of light in the exit pupil expander 200 extending the eye box B according to an embodiment, and FIG. 2C is an exit pupil expander ( 200) is a diagram showing an example in which it is used.

2B and 2C, light from the optical optical device 100 may be incident on the diffraction grating 210 and proceed to diffracted light in three directions and three diffraction orders. That is, the diffracted light of the diffraction orders of "0", "+1" and "-1" is transferred to the second surface 234 of the waveguide 230 facing the first surface 232 on which the diffraction grating 210 is formed. Can proceed (for clarity, thin collimated light (a) and thin collimated light (b) are shown in Figs. 2b and 2c).

When the diffracted light of "0" diffraction order is incident on the second surface 234 of the waveguide 230, since the condition of total internal reflection (TIR) is not satisfied, without total reflection from the second surface 234, the second The waveguide 230 may be completely emitted through the surface 234. All diffracted lights of "0" diffraction order from each parallel light (a, b) are collected in the pupil region 1a of the eye 1 (Fig. 2b), and the exit pupil ( 7) can be formed (Fig. 2b).

When diffracted light of "+1" and "-1" diffraction orders is incident on the second surface 234 of the waveguide 230, it is totally internally reflected at the second surface 234 because the total internal reflection condition is satisfied, and the waveguide ( 230) can be returned to the diffraction grating 210 through the inside. The diffracted light of "+1" and "-1" diffraction orders may proceed with a certain angle deflection during diffraction in the diffraction grating 210 and/or during total reflection in the second surface 234. The diffracted light of "+1" and "-1" diffraction orders may be re-incident to the diffraction grating 210 at a deflected angle.

The diffracted light of diffraction orders of "+1" and "-1" As mentioned above, the diffraction grating 210 decomposes the incident light into diffracted light of three diffraction orders, and each of the diffracted light of diffraction orders of "+1" and "-1" is the diffraction grating 210 It can be diffracted again at "0", "+1" and "-1"

Among the second-order diffracted light, diffracted light of "0" diffraction order is emitted from the waveguide 230, and diffracted light of "+1" and "-1" diffraction order is deflected by a certain angle inside the waveguide 230 to proceed. have,

The diffracted light of "+1" and "-1" diffraction orders may be re-incident to the diffraction grating 210 at a deflected angle. Then, according to the characteristics of the diffraction grating 210, the diffraction grating 210 may diffract the incident light. The diffraction grating 210 repeatedly diffracts the incident light until the light is incident at a specific angle or more, and the waveguide 230 emits light incident below a specific angle and allows total reflection of the light incident above a specific angle. have.

Specifically, the diffracted light of "+1" diffraction order diffracted by the diffraction grating 210 is totally reflected on the second surface 234 of the waveguide 230 and is incident again to the diffraction grating 210. The diffracted light of "+1" diffraction order is diffracted by the diffraction grating 210 and is output as diffracted light of "0", "+1" and "-1" diffraction order, and the diffracted light of "0" diffraction order is waveguide ( The second surface 234 of 230 does not satisfy the total reflection condition, and thus may be emitted to the outside of the waveguide 230. The light emitted to the outside of the waveguide 230 may be the first exit pupil order 8a. The exit pupil order 8 refers to the exit pupil 7 formed by diffracting more than two times by the diffraction grating 210 and then radiating to the outside of the waveguide 230.

The diffracted light of "+1" and "-1" diffraction orders reflected from the second surface 234 of the waveguide 230 is again incident on the diffraction grating 210 to generate third-order diffraction, and the third-order diffracted light The diffracted light of the "0" diffraction order may form an additional exit pupil order 8 while passing through the second surface 234 of the waveguide 230. An additional exit pupil order 8 may be formed in a region adjacent to the first exit pupil order 8a in a direction away from the exit pupil 7.

The second exit pupil order 8b can be formed by repeating total reflection, diffraction, refraction and transmission, and the like, similarly to the diffracted light of the "+1" diffraction order, for a part of the diffracted light of the "-1" diffraction order. The second exit pupil order 8b may be formed in a direction opposite to the first exit pupil order 8a with respect to the exit pupil 7.

The remainder of the diffracted light of the "-1" diffraction order can form an additional exit pupil order 8 by repeating total reflection, diffraction, refraction and transmission, and the like. The additional exit pupil order (8) according to the diffracted light of the "-1" diffraction order is It may be formed in a region adjacent to the second exit pupil order 8b in a direction away from the exit pupil 7. In this way, that the exit pupil order 8 is additionally formed can be referred to as an increase in the exit pupil order 8.

On the other hand, due to the characteristics of the propagation mode of the waveguide 230, an interaction between the diffraction grating 210 and light occurs, and the emitted light in this interaction can accurately correspond to the incident light. That is, the waveform of light at the exit end of the exit dilator 200 may be the same as the waveform of light at the entrance end of the exit dilator 200.

As shown in FIG. 2B, the eye box B (circled for clarity) may include an exit pupil 7 and a plurality of exit pupil orders 8. The number of exit pupil orders 8 may vary depending on the needs of the visual optical device 100 used.

The number of exit pupil orders (8) is determined by the number of exit pupils (7) obtained by the visual optics (100) without the exit pupil expander (200) and the visual optics (100) for proper operation. It can be selected depending on the size of the exit pupil 7 required.

The number of exit pupil orders 8 required to expand the eye box B will be determined by changing a parameter of the diffraction grating 210 and a parameter of the waveguide 230, that is, a parameter for expanding the eye box B. I can.

The number of exit pupil orders 8 (the degree of increase) can be controlled by the thickness of the waveguide 230 and the diffraction angle. For example, the number of exit pupil orders 8 may increase as the thickness of the waveguide 230 decreases, and may increase as the diffraction angle decreases. The distance between the exit pupil orders 8 may be determined by the thickness and material of the waveguide 230. For example, the distance between the exit pupil orders 8 may decrease as the thickness of the waveguide 230 decreases, and may increase as the refractive index of the waveguide 230 increases. The radiation intensity of each exit pupil order 8 extending the eye box B may depend on the diffraction intensity of the diffraction grating 210. For example, the radiation intensity of each exit pupil order 8 may be proportional to the diffraction intensity. A correctly designed exit pupil expander 200 for expanding the eye box B can obtain a predefined number of exit pupil orders 8. Accordingly, the degree of expansion can be controlled in the step of manufacturing the exit dilator 200.

The material of the waveguide 230 included in the exit pupil expander 200 may be, for example, an optical colorless glass, and the refractive index may be selected depending on how many exit pupil orders 8 are required. For example, as the refractive index (plane grade of glass) of the waveguide 230 increases, the angle of total internal reflection increases, and the distance between the exit orders 8 may be located further. In addition, as the refractive index (crown grade glass) of the waveguide 230 decreases, the angle of total internal reflection decreases, and the exit orders 8 may be located closer to each other.

The described principle of propagation of light can be observed in each individual thin parallel light (lights (a, b) in FIGS. 2b and 2c) incident on exit pupil dilator 200.

The exit pupil dilator 200 is not sensitive to displacement relative to the visual optics 100 (the offset of the displacement in FIG. 2C is indicated by “var”). This is because the offset "var" of the displacement does not affect the angle of incidence of light from the visual optical device 100 to the exit pupil expander 200 in order to expand the eye box B, that is, the exit pupil expander 200 The light incident to may depend on the emission angle of the visual optical device 100 described above. The visual optics device 100 integrated with the exit pupil dilator 200 can also form images ranging from the best viewing distance to infinity.

Neither rotation nor rotation about the optical axis 9 affects the angle of incidence to the diffraction grating 210. The parameters of the exit pupil expander 200 are designed according to the angle of incidence determined by the visual optical device 100, and the angle of incidence to the exit pupil expander 200 is the aperture angle of the visual optical device 100, that is, the viewing angle. It is fine if it is designed within the range of.

The expansion (increase or repeat) of the eye box (B) usually occurs as follows (see Figure 2c). The meaning of the object is formed using the visual optical device 100, such as, for example, an augmented reality device or the eyepiece of a microscope, a telescope, a site, etc., and an image of the object is transmitted to the eye 1 and the image of the object May form on the retina of the eye (1). That is, the light reflected from the object passes through the visual optical device 100 and enters the pupil 1a to focus on the retina 1.

In order to expand the eye box B output from the visual optical device 100, the exit pupil expander 200 is disposed at the exit side of the visual optical device 100 along the light, and the exit pupil expander 200 transmits light. Divided into at least two lights, each of which is capable of forming a separate exit pupil 7 and exit pupil order 8. Thus, the exit pupil 7 output from the visual optical device 100 may be increased (expanded) to become an expanded eye box (B).

The exit pupil dilator 200 may be used with an optical device (visual optical device 100) that forms images from the best viewing distance to infinity.

The advantage of the waveguide mode is that the loss of light propagating in the waveguide 230 is very small. Accordingly, since the exit pupil expander 200 according to an exemplary embodiment includes a diffraction grating 210 used for both incidence and emission of light and a conduit tube to which a conduit mode is applied, there is little light loss. That is, all the light from the visual optical device 100 may be included in the shape of the exit pupil order 8 constituting the eye box B.

Further, since the eye 1 is an optical receiver, it is preferable that the light emitted from the visual optical device 100 is parallel light. Parallel light enters the eye 1, and the parallel light is focused by a lens on the retina (essentially a condensing lens), and a person can see the object clearly. When non-parallel light is emitted from the visual optical device 100, an image formed on the retina of the eye 1 may be blurred. That is, the image may be formed in front of or behind the retina, not in the retina. Even after the light in the form of parallel light from the visual optical device 100 propagates through the exit pupil expander 200 according to an exemplary embodiment, the light may be kept parallel.

The exit pupil expander 200 can be applied to the visual optics device 100 using single spectrum light and multispectral light to form a color image. This is because a single diffraction grating 210 is used to enter light into the waveguide 230 and emit light from the waveguide 230, and the waveguide 230 satisfies the waveguide 230 mode. Thus, the light incident on the exit pupil expander 200 increases and exits into a plurality of lights without changing the optical characteristics, and the exit pupil 7 and a plurality of exit pupil orders 8 can be formed.

The exit pupil expander 200 may operate in a transmissive mode, as shown in FIG. 2C, but is not limited thereto. The exit pupil expander 200 may also operate in a reflective mode.

2D is a diagram illustrating an exit pupil expander 200 operating in a reflection mode according to an exemplary embodiment.

As shown in FIG. 2D, incident light (eg, parallel light) from the visual optical device 100 is a waveguide 230 corresponding to the first surface 232 of the waveguide 230 on which the diffraction grating 210 is formed. ) May be incident on the second surface 234.

The parallel light refracted by the waveguide 230 may be obliquely incident on the reflection type diffraction grating 210.

In the reflective diffraction grating 210, light can be diffracted into diffracted light of three diffraction orders, that is, "0", "+1" and "-1" diffraction orders, and propagate in the guiding tube in three directions.

Since the diffracted light of "0" diffraction order, that is, part of the light diffracted once, passing through the waveguide 230 and incident on the second surface 234, does not satisfy the condition of total internal reflection, the surface 6 Without total reflection, it may be completely emitted from the waveguide 230 through the second surface 234.

The diffracted light of the "0" diffraction order is collected in a partial area of the pupil region of the eye 1a, and an exit pupil 7 can be formed in the eye box B (similar to the operation of the transmission mode).

The diffracted light of the "+1" and "-1" diffraction orders catalyzes the total reflection condition at the second surface 234, and is totally reflected at the second surface 234 (as described for the device operating in the transmission mode). It may proceed into the waveguide 230.

The diffracted light of "+1" and "-1" diffraction order is again incident on the diffraction grating 210, and the diffraction cost is "0" using each of the diffracted light of "+1" and "-1" diffraction order, The diffracted light of the diffraction order of +1" and "-1" is output. Each of the diffracted light of the diffraction order of "0" according to the second diffraction is emitted to the second surface 234 of the waveguide 230 and exits the exit pupil order. (8) is formed, and the remaining diffracted light passes through the waveguide 230 again.

The light passing through the guide tube is repeatedly diffraction, transmission, total reflection, and refraction until the incident angle incident on the diffraction grating 210 reaches an angle that cannot be diffracted. Can be additionally formed.

Similar to the operation of the exit dilator 200 in the transmissive mode, the eye box B formed by the exit dilator 200 in the reflective mode is a set of exit pupil 7 and exit pupil orders (8). of orders of the exit pupil). As described above, the number of orders of the exit pupil 7 may be arbitrary. That is, it may be necessary for a visual optical system to which the exit pupil expander 200 is applied, and the degree of increase of the exit pupil order 8 is a parameter of the exit pupil expander 200, that is, the diffraction grating 210 and the waveguide 230 Can be adjusted by the parameters of.

As described above, in the exit pupil expander 200 in which the reflective diffraction grating 210 for expanding the eye box B is used, the propagation principle of light is the exit pupil expander in which the transmission diffraction grating 210 is used ( 200). The only difference is the orientation of the exit pupil dilator 200 along the optical axis of the visual optics device 100.

In the case of the exit pupil expander 200 operating in the transmission mode, light is first propagated through the transmission type diffraction grating 210, and the eye box B may be formed behind the exit pupil expander 200 (see FIG. 2C). . In the case of the exit pupil expander 200 operating in the reflection mode, light may be first incident and refracted through the waveguide 230 to be incident on the reflective diffraction grating 210. The eye box (B) may be formed in front of the exit dilator 200 (Fig. 2d).

The visual field of the visual optical system was measured when the exit dilator 200 was applied to the visual optical device 100 and when the exit dilator 200 was not applied. As a result of the measurement, it was confirmed that the visual optical system to which the exit pupil expander 200 is applied has a field of view that is extended by 5 times or more compared to the visual optical system to which the exit pupil expander 200 is not applied.

Further, in the exit pupil expander 200, since light propagates over a very short distance in the waveguide 230, light energy loss can be reduced.

The high diffraction efficiency of the exit pupil expander 200 allows the light to be uniformly filled in the eye box (B).

3 shows a space diagram of a display using an exit pupil expander according to an embodiment. The display of FIG. 3 is a near-eye display and may be an augmented reality device.

Light from the image source F may be incident on the combiner 300 that combines an image of the environment with an image formed by the image source F (eg, an internal display). The coupler 300 may correspond to the optical optical device 100 described in FIGS. 1 and 2B. The combiner 300 may redirect light to the exit pupil expander 200 to form the size of the field of view of the augmented reality device and expand the eye box B.

The exit pupil expander 200 may increase the eye box B of the augmented reality device as described above. Light emitted from various areas (a, b, c, and d of FIG. 3) of the exit dilator 200 may be redirected to the eye 1 at various angles. The light emitted from the exit pupil expander 200 may completely and uniformly fill the eye box B including the exit pupil 7 and the exit pupil order 8. This is because light propagates from the augmented reality device through the exit pupil expander 200. In this case, the exit pupil expander 200 for the augmented reality device may be two-dimensional because the two-dimensional diffraction grating 210 is used. That is, the eye box B may extend in two mutually perpendicular directions on the same plane.

When the combiner 300 is based on a holographic optical element, it is known that the combiner 300 has a small eye box (B). In order to expand the eye box (B) of the coupler 300, if the proposed exit pupil expander 200 is used to expand the eye box (B), it may be useful.

4A is a view showing a coupler and an exit pupil expander operating in a transmission mode according to an embodiment. The combiner 300 and exit pupil expander 200 of FIG. 4A may be integrated into an augmented reality device as a display. The augmented reality device may be a glasses type. The coupler 300 may be a holographic optical element. The image may be formed behind the coupler 300, ie opposite the coupler 300 being highlighted. The exit dilator 200 may be disposed behind the combiner 300 closer to the eye 1. That is, the coupler 300 may be disposed between the exit dilator 200 and the eye 1.

Light from the image source F is incident on the coupler 300, and the viewing angle of the coupler 300 may be formed by inclined parallel light. The light emitted from the coupler 300 is incident on the exit pupil expander 200, and as described above, the exit pupil 7 and a plurality of exit pupil orders 8 may be formed. The light emitted from the exit dilator 200 may be propagated through the coupler 300 without interacting with the coupler 300. That is, the coupler 300 does not affect the propagation of light corresponding to the exit pupil 7 and the exit pupil order 8 output from the exit pupil expander 200.

4B is a diagram illustrating a relationship between a coupler 300 operating in a reflection mode and an exit dilator 200 according to an exemplary embodiment. That is, the image formed by the coupler 300 may be formed in front of the coupler 300 on the same side as the image source F. In this case, the exit pupil expander 200 may also be disposed in front of the combiner 300, and the exit pupil expander 200 may be disposed closer to the eye 1 than the combiner 300. In addition, the coupler 300 forms a viewing angle, and the exit pupil expander 200 forms an additional exit pupil order 8 to expand the eye box B.

Since the exit pupil expander 200 is compact, it can be easily integrated into the augmented reality device without substantially changing the overall dimensions and weight of the augmented reality device.

5 is a diagram conceptually showing an exit pupil expander including a one-dimensional diffraction grating according to an embodiment. As shown in FIG. 5, when the exit pupil expander 200 includes a one-dimensional diffraction grating 210, light from the visual optical device 100 may be incident and diffracted by the exit pupil expander 200. . The light propagating from the visual optical device 100 and the light diffracted from the exit pupil expander 200 may have the same plane image.

As described above, the diffracted light of "0" diffraction order passes through the exit pupil expander 200, and the diffracted light of "+1" and "-1" diffraction order is transmitted to the waveguide 230 by total reflection in the waveguide 230. ) Propagates along the Y axis, and is again incident on the diffraction grating 210 to be diffracted into diffracted light having diffraction orders of "0", "+1" and "-1".

Among the light diffracted twice, diffracted light having a diffraction order of "0" does not satisfy the condition for total reflection, and thus may pass through the waveguide 230 to form the exit pupil order 8. In the same manner as described above, the light exits the exit pupil expander 200 while diffraction, total reflection, and refraction in the exit pupil expander 200, and forms an additional exit pupil order 8 along one axis (Y). can do. That is, the area 7 of the exit pupil 7 can only be extended in one direction.

Unlike the 1D diffraction grating 210, the 2D diffraction grating 210 may plot the exit pupil order 8 in two orthogonal directions. 6 is a conceptual diagram illustrating an exit pupil expander including a two-dimensional diffraction grating according to an exemplary embodiment. 6, when the exit pupil expander 200 includes a two-dimensional diffraction grating 210, light from the visual optical device 100 enters the two-dimensional diffraction grating 210 and is in two directions ( Diffracted along the X and Y axes). The operating principle is the same as the one-dimensional diffraction grating 210, but the expansion of the eye box B can occur in two directions. That is, the eye box B may be extended to two coordinates.

7 is a view showing an exit pupil expander according to another embodiment. 7, the diffraction grating 210 may be located inside the waveguide 230. For example, the exit pupil expander 200 may include a first waveguide 230a, a second waveguide 230b, and a diffraction grating 210 disposed between the first waveguide 230a and the second waveguide 230b. I can. Each of both ends of the diffraction grating 210 may contact the first and second waveguides 230a and 230b. Light incident on the diffraction grating 210 through the first waveguide 230a may be divided into two parts.

Some of the light incident on the diffraction grating 210 may pass through the diffraction grating 210 while diffracting the diffraction grating 210 to proceed to the first waveguide 230a. Light traveling through the first waveguide 230a is diffracted light of "0", "+1" and "-1" diffraction order, and the diffracted light of "0" diffraction order passes through the first waveguide 230a Form the movement (7). The diffracted light of "+1" and "-1" diffraction orders can form an additional exit pupil order 8 by repeating total reflection, refraction, diffraction, and transmission, and the like.

Meanwhile, some of the light incident on the diffraction grating 210 may be reflected by the diffraction grating 210 while diffracting the diffraction grating 210 to proceed to the second waveguide 230b. The diffracted light that has traveled through the second waveguide 230b may be totally internally reflected by the second waveguide 230b and may be incident again to the diffraction grating 210. Some of them may pass through the diffraction grating 210 and others may be reflected from the diffraction grating 210.

As described above, the transmitted light may form an additional exit pupil order 8 while traveling through the first waveguide 230a. The diffracted light reflected by the second waveguide 230b may be transmitted through the first waveguide 230a while repeating total reflection and diffraction. . Due to the first waveguide 230a, light may be uniformly distributed to the exit pupil orders 8.

8A is a diagram illustrating an eye box including a plurality of discretely distributed exit orders. The light emitted from the optical optical device 100 may itself form a plurality of exit pupils 7. The plurality of exit pupils 7 formed by the visual optical device 100 may be distributed unevenly (discretely) in the eye box B, as shown in Fig. 8A. Thus, the blind area 10 may be formed in the eye box B. Since the exit pupil order 8 does not exist in the blind area 10, the user's eyes 1 can be changed to the blind area 10 If located in, you cannot see the image.

The exit pupil expander 200 according to an embodiment may form and increase the exit pupil order 8. The resolution of the eye box B, that is, the number of the exit pupil orders 8 increased by the exit pupil expander 200 may vary according to the following two parameters.

-The diffraction angle of the diffraction grating 210 (that is, the angle of incidence of light into the waveguide 230) and

-Thickness and material of the waveguide 230 (ie, total internal reflection angle)

By combining these two parameters, the number of total reflections of the waveguide 230 and the degree of discontinuity of the exit pupil order 8 can be controlled. For example, as the diffraction angle of the diffraction grating 210 decreases or the total internal reflection angle of the waveguide 230 decreases, the resolution of the eye box B may increase.

8B is a diagram illustrating an exit pupil order formed by an exit pupil expander according to an exemplary embodiment. The exit pupil expander 200 according to an embodiment may increase the exit pupil order 8 through diffraction, transmission, refraction, and total reflection. The exit pupil orders 8 may be formed so that at least some regions do not overlap with each other. As shown in FIG. 8B, as the exit pupil order 8 increases, that is, as the eye box B is filled with the exit pupil orders 8, discreteness disappears, and the eye box B may become uniform.

Also, in order for the image to be homogeneous, the light energy in each exit pupil 7 and exit pupil order 8 would have to be the same. Otherwise, the eye 1 may see a very bright image in one position and the eye 1 in another position may see a very faint image.

The uniformity of light energy in each of the exit pupil 7 and exit pupil order 8 can be achieved by optimizing the parameters of the diffraction grating 210. To this end, during manufacture, the period of the diffraction grating 210 may be selected so that the light at the point of incidence and the point of exit of the exit pupil expander 200 is matched, and the exit pupil 7 and the exit pupil order 8 respectively The relief height of the diffraction grating 210 may be selected so that it is uniformly bright and has the same dimensions. The exit dilator 200 may have an angular range capable of accurately operating. This range may be greater than or equal to the size of the viewing angle of the visual optical device 100, that is, the aperture angle of the visual optical device 100.

For example, when the exit pupil expander 200 according to an embodiment is designed to operate within a 60° opening angle range, the exit cast expander 200 may also be less than 60° (eg, 40°). It can also be used for the visual optical device 100 having a viewing angle. However, when the viewing angle of the visual optical device 100 is greater than 60°, the exit pupil expander 200 can no longer be applied to such a device. In this case, this is because the exit exit expander 200 does not operate properly.

When the exit pupil expander 200 includes a planar waveguide, any type of diffraction grating 210 may be applied to the diffraction grating 210. However, the planar exit pupil dilator 200 is generally useful for a visual optics device 100 having a small field of view.

9A is a diagram illustrating a planar exit exit expander forming a spot according to an exemplary embodiment.

As shown in FIG. 9A, light having different viewing angles may be incident on the exit pupil expander 200. For example, a useful first light, such as an image, incident at a first viewing angle Θ ₁ , and a second light, such as a player, incident at _{a second viewing angle Θ 2, are exit pupil expander 200} Can be incident on. In addition, the size of the opening angle of the exit pupil expander 200 may be equal to _{the first viewing angle Θ 1.} When the first light is incident on the exit pupil expander 200, the exit pupil expander 200 uses the first light to form the exit pupil 7 and a plurality of exit pupil orders 8 in the eye box (B). I can.

On the other hand, when the second light is incident on the exit dilator 200 at an incidence angle Θ _{2 greater than the first opening angle Θ 1 of the exit dilator 200, the exit dilator 200 is} The exit pupil order (8) cannot be formed. Thus, the exit pupil expander 200 may form a "rainbow" spot on the eye box B, as shown in FIG. 9A. As for the second light, an additional light source, for example, a street light, a street light, a car headlight, etc., can be seen through the visual optical device 100, but the second light is diffracted by the diffraction grating 210, but the waveguide ( 230) and thus appear as a spectral form (eg "rainbow"). This phenomenon can be observed when using the exit pupil expander 200 in the augmented reality glasses having a small eye box (B).

10 is a view showing a curved exit exit expander according to an embodiment.

Due to the change in the shape of the exit pupil expander 200, the exit pupil expander 200 may be implemented to operate only at a specific opening angle. That is, the curvature of the exit pupil expander 200 may be designed to realize the selectivity of the opening angle.

The curved exit pupil expander 200 may include a curved diffraction grating 210 and a curved waveguide 230 as shown in FIG. 10. The first light incident into the first opening angle Θ ₁ may be directed in a direction perpendicular to the exit pupil expander 200. It has a curvature that can be varied or adjusted within the desired range of the exit angle dilator 200, i.e., the desired range of the angle of incidence (the range of the angle of incidence can be set by the visual optics device 100 designed for use). Because there is.

The first light incident within the first opening angle Θ ₁ is diffracted by the diffraction grating 210, and the waveguide 230 forms the exit pupil 7 and the exit pupil order 8 using the diffracted light. Thus, the eye box (B) can be expanded. However, the second light incident at the second opening angle Θ2 greater than the first opening angle Θ1 may not form the eye box B. This is because even though the diffraction grating 210 diffracts _{the second light incident at the second opening angle Θ 2} , the diffracted light is totally internally reflected by the waveguide 230 and is not emitted to the outside.

When the exit pupil expander 200 uses the curved waveguide 230, the diffraction grating 210 may use a Bragg diffraction grating. Bragg diffraction gratings have the advantage of high diffraction efficiency. Also, the Bragg diffraction grating may be selective for the incident angle of light and the wavelength of light.

The Bragg diffraction grating may also be used in a planar waveguide or a planar exit pupil expander when it is necessary to increase the efficiency of light incident at a specific angle in the viewing angle range of the visual optical device 100. Thus, light incident on the diffraction grating 210 may be output with minimal energy loss, and light incident on the diffraction grating 210 may increase energy loss.

When a volume Bragg grating is used as the diffraction grating 210, the efficiency of light incident from the visual optical device 100 at a specific angle may be further increased.

The main advantage of using the curved waveguide is that the exit pupil expander 200 according to an embodiment can be incorporated even in the visual optics device 100 having a very large viewing angle. The planar exit exit expander has a limit in the incident angle of light for expanding the eye box (B). Thus, when the viewing angle of the visual optical device 100 exceeds the limit of the opening angle of the exit pupil expander 200, the exit pupil expander 200 cannot correctly expand the eye box B. However, since the curved exit pupil expander can expand or adjust the opening angle by curvature, it can also be applied to the visual optical device 100 having a large viewing angle.

On the other hand, even in the case of the flat-type exit pupil expander, the opening angle may be widened by using a plurality of guiding tubes. 11 is a diagram illustrating an exit pupil expander including a plurality of waveguides according to another exemplary embodiment. As shown in FIG. 11, a partial region of the _{diffraction grating 210 diffracts the first light incident into the first opening angle Θ 1} , and the remaining region of the diffraction grating 210 is the first opening angle Θ It may be designed to diffract light incident into the second opening angle Θ _{2 greater than 1 ).} The parameters of the diffraction grating 210 may be designed to correspond to the aperture angle.

The first waveguide pipe forms the exit pupil 7 and the exit pupil order 8 by using the first light incident into the first opening angle Θ _{1, and the second waveguide 230b forms the first opening angle (} The exit pupil 7 and the exit pupil order 8 may be formed by using the second light exceeding Θ1 and incident into the second opening angle Θ _2. Accordingly, a plurality of waveguides 230 may be used to widen the viewing angle.

The exit pupil expander 200 described so far can be widely applied to the visual optics device 100 as a compact and convenient additional element for expanding the eye box B of the visual optics device 100.

The above-described exit dilator and display have been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the art can recognize that various modifications and other equivalent embodiments are possible. I will understand. Although many items are specifically described in the above description, they should be construed as examples of specific embodiments rather than limiting the scope of the invention. Accordingly, the scope of the present invention should not be determined by the described embodiments, but should be determined by the technical idea described in the claims.

100: visual optics
200: exit dilator
210: diffraction grating
230: waveguide
B: Eye box
7: exit building
8: exit pupil order

Claims (22)

In the exit pupil expander for expanding the exit pupil of the visual optical device,
A diffraction grating for diffracting the incident light to output a plurality of diffracted lights having different diffraction orders; And
Arranged on the diffraction grating, an exit pupil is formed using a first diffracted light among the plurality of diffracted lights output from the diffraction grating, and an exit pupil order is determined by using a second diffracted light among the plurality of diffracted lights. An exit pupil dilator comprising a; waveguide to form. The method of claim 1,
The waveguide,
An exit pupil expander configured to form the exit pupil by outputting the first diffracted light output from the diffraction grating without total reflection. The method of claim 1,
The waveguide,
An exit pupil expander configured to form at least one exit pupil order by totally internally reflecting the second diffracted light output from the diffraction grating at least once and then outputting it. The method of claim 3,
The waveguide reflects the second diffracted light in total internally to re-enter the diffraction grating,
The diffraction grating diffracts the second diffracted light and outputs it as a plurality of diffracted light,
The waveguide forms an exit pupil order by outputting some of the diffracted light according to the diffraction of the second diffracted light, and re-enters the diffraction grating by totally reflecting the remaining diffracted light of the plurality of diffracted light. The method of claim 1,
The waveguide,
And a first surface facing the diffraction grating
An exit pupil expander comprising a second surface facing the first surface and outputting the first diffracted light to the outside. The method of claim 5,
The waveguide,
An exit pupil expander that additionally forms the exit pupil order until all of the diffracted light incident on the second surface is totally reflected. The method of claim 5,
The number of exit pupil orders is,
An exit pupil expander in proportion to the number of times a portion of the diffracted light incident on the second surface of the waveguide is transmitted. The method of claim 5,
The spacing between the exit pupil orders is,
An exit dilator proportional to the thickness of the conduit tube. The method of claim 5,
The spacing between the exit pupil orders is,
An exit dilator that is inversely proportional to the refractive index of the conduit tube. The method of claim 1,
The first diffracted light is diffracted light having a diffraction order of "0",
The first diffracted light includes at least one of diffracted light having a diffraction order of "+1" and diffraction light having a diffraction order of "-1". The method of claim 10,
The waveguide is
The first exit pupil order is formed using diffracted light having the "+1" diffraction order,
An exit pupil expander for forming a second exit pupil order by using diffracted light having the "-1" diffraction order. The method of claim 10,
The waveguide is
An exit pupil expander configured to form the first exit pupil order and the second exit pupil order in different directions with the exit pupil interposed therebetween. The method of claim 1,
The diffraction grating,
An exit pupil expander that diffracts incident light below a specific aperture angle. The method of claim 1,
The opening angle is,
The exit pupil dilator larger than the viewing angle of the visual optics device. The method of claim 1,
The exit pupil expander further comprising a; second waveguide disposed on the diffraction grating and totally reflecting the light output from the diffraction grating. The method of claim 14,
The diffraction grating,
An exit pupil expander disposed between the first waveguide and the second waveguide. The method of claim 1,
The diffraction grating,
A first diffraction region for diffracting light incident below a first aperture angle and a second diffraction region for diffracting light incident at a second aperture angle greater than or equal to the first aperture angle,
The conduit is
A first waveguide forming an exit pupil order by using the diffracted light output to the first diffraction region; And
And a second waveguide for forming an exit pupil order by using the diffracted light output from the second diffraction region. The method of claim 1,
The diffraction grating, the first waveguide, and the second waveguide are sequentially arranged based on a path of the light. The method of claim 1,
The waveguide is an exit dilator comprising a curved type. The method of claim 1,
The diffraction grating,
Exit pupil expander with Bragg diffraction grating. Visual optics that emit light at a specific viewing angle; And
Display comprising; the exit pupil expander according to claim 1 for expanding the exit pupil region of the visual optical device. The method of claim 21,
The display is a near-eye display.

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