KR101910983B1 - Nanostructured acousto-optic device, and optical scanner, light modulator and holographic display apparatus using the nanostructured acousto-optic device - Google Patents

Abstract

An acoustooptic device in which the diffraction angle range of output light is increased by using a nanostructured medium and an optical scanner, an optical modulator and a holographic display device using the same are disclosed. The disclosed acousto-optic element may comprise a nanostructure of at least two different media arranged alternately, of which at least one medium is an acoustooptic medium. According to the embodiment of the present invention, the acoustooptic device having the above-described structure can further increase the diffraction angle range of the output light. Thus, various systems such as optical scanners, optical modulators, 2D / 3D display devices, holographic display devices, etc. using the disclosed acousto-optic elements may not require a separate optical system to widen the operating angle range. As a result, the overall system size can be further miniaturized, and resolution constraints can be improved.

Description

[0001] The present invention relates to a nanostructured acousto-optic device, and more particularly, to a nanostructured acousto-optic device and an optical scanner using the acousto-optic device using the nanostructured acousto-optic device,

The disclosed invention relates to a nanostructured acousto-optic element and an optical scanner and an optical modulator using the acoustooptic element, and more particularly, to a method of increasing the diffraction angle range of the output light or adjusting the diffraction angle characteristic by using a nanostructured medium And an optical scanner, an optical modulator and a holographic display device using the same.

The acousto-optic effect is the effect of periodically changing the refractive index of light in the medium by modifying the medium with sonic or ultrasonic waves. Due to this acousto-optic effect, the medium can act as a phase grating, and therefore the light incident on the medium can be diffracted. Further, a medium having such an acousto-optic effect is generally called a medium. The intensity and the diffraction angle of the diffracted light by the medium vary depending on the intensity and the frequency of the sound wave, respectively. Therefore, an acoustooptic device having a structure in which a sound wave generator such as an ultrasonic wave generator is mounted on the surface of a medium having the above-mentioned properties can be variously applied in an optical modulator for modulating the amplitude of light or a light scanner for deflecting light .

However, the acousto-optic devices using the existing medium in the natural state have a limitation on the diffraction angle of the output light due to the limited optical anisotropy of the medium and the acousto-optic conversion ratio. That is, in the case of the conventional acoustooptic device, the diffraction angle range of the output light is not sufficiently wide. Therefore, in various optical applications such as optical scanners, optical modulators, and displays, there is a need for a separate optical system for compensating for a narrow diffraction angle range when using an acoustooptic device. This can cause the overall system to increase in size or degrade the resolution.

The present invention provides an acoustooptic device in which the diffraction angle range of output light is increased by using a nanostructured medium.

Also, an optical scanner, an optical modulator, and a holographic display device using the acousto-optic device are provided.

The disclosed acousto-optic element may comprise a nanostructure of at least two different media arranged alternately. The acoustooptic element having the above-described structure can further increase or adjust the diffraction angle range of the output light. Thus, various systems such as optical scanners, optical modulators, displays, etc., using the disclosed acousto-optic elements may not use a separate optical system to widen the diffraction angle range. Therefore, the size of the overall system can be further miniaturized, and resolution constraints can be improved.

1 is a perspective view showing a schematic structure of an acoustooptic device according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing the operation of the acousto-optic device shown in Fig.
3 is a perspective view showing a schematic structure of an acoustooptic device according to another embodiment of the present invention.
4 is a perspective view showing a schematic structure of a light scanner according to an embodiment of the present invention using the acousto-optic device shown in Figs. 1 and 3. Fig.
FIG. 5 is a cross-sectional view schematically illustrating a process of light propagating in an optical waveguide of the optical scanner shown in FIG.
FIG. 6 schematically shows a cross-sectional view of the optical scanner shown in FIG. 4 cut in a direction perpendicular to the light traveling direction.
FIG. 7 schematically shows a method of scanning a color image using the three optical scanners shown in FIG.
Fig. 8 schematically shows another way of scanning a color image using one optical scanner shown in Fig.
FIG. 9 schematically shows an example in which the acousto-optic element shown in FIG. 1 and FIG. 3 is applied to a 2D / 3D converted stereoscopic image display apparatus.
Fig. 10 schematically shows an example in which the acousto-optic element shown in Figs. 1 and 3 is applied to a holographic display device.

Hereinafter, a nanostructured acoustooptic device and an optical scanner, an optical modulator, and a holographic display device using the acoustooptic device will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

1 is a perspective view showing a schematic structure of an acoustooptic device according to an embodiment of the present invention. 1, an acoustooptic device 10 according to an embodiment of the present invention includes a nano-structured acousto-optic medium 30 and a sonic generator 30 for applying a sonic wave to the nano-structured acoustooptic medium 30 15). In addition, the nanostructured acoustooptic medium 30 may include a first medium 11 and a second medium 12, which are alternately arranged and have different dielectric constants. The sound wave generator 15 may be disposed on one side of the nano-structured acousto-optic medium 30, for example, on one surface of the first medium 11.

Here, one of the first medium 11 and the second medium 12 may be a general acousto-optic medium having a relatively large acousto-optic conversion ratio. The other one may be made of an acousto-optic medium having a relatively small acousto-optic conversion ratio, or even of a material (for example, air) which has little acousto-optic conversion ratio. Also, according to an embodiment of the present invention, the first medium 11 and the second medium 12 may have different real part signs of the dielectric constant. For example, one of the first medium 11 and the second medium 12 may have a positive (+) value of the dielectric constant and the other may have a negative (-) value of the dielectric constant . Examples of the material in which the real part of the permittivity is negative include metal materials such as Al, Ag, Au, Cu, Na and Ka, or alloys thereof, indium tin oxide (ITO), aluminum doped zinc oxide A semiconductor such as gallium zinc oxide (GZO) or the like, or graphene. In addition, one of the first and second media 11 and 12 may have a gain material and a gain structure capable of amplifying light. In this case, one of the first and second media 11 and 12 may be a III-V semiconductor such as GaN, Al _1-x Ga _x N, In _1-x Ga _x N, ), An organic crystal, or the like. The period in which the first medium 11 and the second medium 12 alternate may be smaller than the wavelength of light to be controlled by the acoustooptic element 10 (for example, visible light).

In FIG. 1, two media 11 and 12 having different dielectric constants are shown as being alternated. However, two or more media having different dielectric constants (for example, three media) may be alternated with each other . In this case, at least one of the two or more media may be made of an acousto-optic material having a relatively high acousto-optic conversion ratio. Also, at least one of the two or more media may be made of a material having a relatively small or almost no acousto-optic conversion ratio. The alternating period of two or more media may also be smaller than the wavelength of the incident light to be controlled.

The arrangement order of the first medium 11 and the second medium 12 may be arranged in advance. 1 shows that the sound wave generator 15 is disposed on the surface of the first medium 11 but when the second medium 12 is disposed first, (15) may be disposed. The sound wave generator 15 may be an electro-acoustic modulator capable of generating an acoustic acoustic wave, for example, an ultrasonic wave according to an applied electrical signal. 1, in the acoustooptic device 10 according to an embodiment of the present invention, a sound wave generated by the sound wave generator 15 is reflected by the first medium 11 and the second medium 12 in the stacking direction The sound wave generator 15 can be arranged to be able to move along the first direction.

2 is a cross-sectional view schematically showing the operation of the acoustooptic device 10 according to an embodiment of the present invention shown in FIG. 2, when an electric signal is applied to a sound wave generator 15 disposed on one side of a nano-structured acoustooptic medium 30, a sound wave such as an ultrasonic wave having a predetermined amplitude and frequency corresponding to the electric signal Lt; / RTI > The sound waves generated by the sound wave generator 15 travel inside the nano-structured acousto-optic medium 30 at a predetermined speed as indicated by arrows in FIG. At this time, the sound wave repeats compression and rarefaction in the nano-structured acoustooptic medium 30. Accordingly, the local density in the nano-structured acousto-optic medium 30 is also changed corresponding to the pushing or bending of the sound wave proceeding inside the nano-structured acousto-optic medium 30. This change in local density can lead to a local change in refractive index. As a result, when a sound wave advances in the nano-structured acoustooptic medium 30, a periodic variation of the refractive index occurs along a direction parallel to the propagation direction of the sound wave and at the same period as the wavelength of the sound wave. For example, the refractive index inside the nano-structured acousto-optic medium 30 is repeatedly increased / decreased corresponding to the repetitive pushing and bending of the sound waves.

Then, from the optical point of view, the same effect as that of forming the periodic lattice in the nano-structured acoustooptic medium 30 can be obtained. Thus, the light incident on the nanostructured acousto-optic medium 30 can be diffracted or blocked by an optical grating formed by a periodic change in refractive index within the nanostructured acoustooptic medium 30. The diffraction angle of the light by the nano-structured acousto-optic medium 30 and the intensity of the diffracted light may vary depending on the frequency and intensity of the sound waves, respectively. In addition, the frequency and intensity of the sound wave can be determined by the intensity and frequency of the electric signal applied to the sound wave generator 15. Therefore, it is possible to control the diffraction of light in the nano-structured acousto-optic medium 30 by appropriately controlling the electric signal applied to the sound wave generator 15. [

2, in order to diffract the light incident on the nano-structured acousto-optic medium 30, the direction of propagation of the sound wave in the nano-structured acousto-optic medium 30 and the propagation direction of the nano- structured aco-optical medium 30 30 are arranged so as to intersect with each other. That is, when light is incident on other peripheral surfaces adjacent to the surface of the nanostructured acousto-optic medium 30 in which the sound generator 15 is disposed, the above-described diffraction effect may occur.

2, the first medium 11 and the second medium 12 having different permittivities along the traveling direction of a sound wave are repeatedly formed in the acousto-optical element 10 according to an embodiment of the present invention, Respectively. According to an embodiment of the present invention, the difference in the refractive indexes (that is, the refractive index anisotropy) depending on the incident angle can be increased due to the repetition of these two different media 11 and 12. As a result, the angular range [Delta] [theta] over which the constructive interference of the diffracted light occurs can be widened, and consequently the angle at which the light is diffracted can be increased. To this end, the sum of the thicknesses (d1, d2) of the first and second mediums (11, 12), which are periodically repeated in the first medium (11) ) Is much smaller than the wavelength of the incident light. By combining the thicknesses d1 and d2 of the first and second media 11 and 12 with the dielectric constant characteristics, it is possible to adjust the refractive index anisotropy and the diffraction operation angle range in the nano-structured acoustooptic medium 30 It is possible. According to the above-described principle, in the light diffracted by the nano-structured acoustooptic medium 30, the angular difference ?? between the first order diffracted light L0 and the second diffracted light L1 is used as a single medium As compared with the case of the case of FIG.

3 is a perspective view showing a schematic structure of an acoustooptic device 20 according to another embodiment of the present invention. The acoustooptic element 20 shown in Fig. 3 is similar to the acoustooptic element 10 shown in Fig. 1, but in the arrangement direction of the nanostructure media 13 and 14 in the nano-structured acoustooptic medium 40 There is a difference. That is, as shown in FIG. 3, the first medium 13 and the second medium 14 may be repeatedly arranged alternately along a direction perpendicular to the traveling direction of the sound waves. The sound wave generator 15 is disposed over the side surfaces of the first and second mediums 13 and 14 alternating with each other. Even in this case, light incident on other peripheral surfaces adjacent to the surface of the nanostructured acousto-optical medium 40 in which the sound wave generator 15 is disposed can be diffracted. Accordingly, the traveling direction of the sound wave in the nano-structured acousto-optic medium 40 and the traveling direction of the light incident on the nano-structured acousto-optic medium 40 can be arranged to intersect with each other.

As shown in FIGS. 1 and 3, the nano-structured acoustooptic devices 10 and 20 can be applied to various fields.

For example, the acousto-optic elements 10 and 20 can adjust the intensity of the 0th-order diffracted light according to the degree of diffraction of the light, and thus can be an optical modulator for the 0th order diffracted light as such. For example, since incident light is not diffracted unless sound waves are applied to the acousto-optic elements 10 and 20, the incident light will pass through the acoustooptic elements 10 and 20 with little loss. When the acoustic wave is applied to the acousto-optic elements 10 and 20 to diffract the incident light, the intensity of the 0th-order diffracted light passing through the acoustooptic elements 10 and 20 will be weakened because the 1st-order diffracted light is generated. And, if more energy is distributed to the 1st-order diffracted light depending on the degree of diffraction, the intensity of the 0th-order diffracted light can be further weakened. Therefore, the acousto-optic elements 10 and 20 can serve as an optical modulator for amplitude-modulating the intensity of the 0th-order diffracted light.

Further, the acousto-optic elements 10 and 20 may be applied to a light scanner which deflects incident light at a predetermined angle by changing the diffraction angle of the first-order diffracted light. Particularly, when the acousto-optic elements 10 and 20 according to the embodiment of the present invention are used in a light scanner, the operation range (that is, the scanning range) of the light scanner can be widened. It can be done simply. In particular, a separate optical system required to increase the diffraction angle range may not be used.

4 is a perspective view schematically showing a schematic structure of a light scanner using the acousto-optic elements 10 and 20 shown in Figs. 1 and 3. Fig. 4, a light scanner 100 according to an exemplary embodiment of the present invention includes a substrate 101, an optical waveguide 110 disposed in the substrate 101, a light beam incident on the optical waveguide 110, A first acoustooptic device 132 disposed in the optical waveguide 110 and deflecting light in a horizontal direction and a second acoustooptic device 132 disposed in the optical waveguide 110 to deflect light in a vertical direction 2 acousto-optic element 134 as shown in FIG. The first acousto-optical element 132 may include a first sonic wave generator 131 for applying sonic waves to the first acousto-optical element 132 and the second acoustooptic element 134 may include the second acousto- And a second sound wave generator 133 for applying a sound wave to the element 134. The second acoustooptic device 134 controls the light guided by the optical waveguide 110 to output light outside the optical waveguide 110 and adjust the vertical angle of the output light. Here, the first acoustooptic element 132 and the second acoustooptic element 134 may be any of the acoustooptic elements 10 and 20 shown in Figs. 1 and 3. The first sound wave generator 131 and the second sound wave generator 133 may be disposed adjacent to the sides of the first acoustooptic element 132 and the second acoustooptic element 134 on the substrate 101, respectively.

FIG. 5 is a cross-sectional view schematically showing the progress of light in the optical waveguide 110 of the optical scanner 100 shown in FIG. 5 shows only the cross-sectional structure of the substrate 101, the optical waveguide 110 and the optical coupling element 120 by omitting the first and second acousto-optical elements 132 and 134 in the optical waveguide 110 have. Referring to FIG. 5, light emitted from an external light source (not shown) enters the photocoupling element 120. The optical coupling element 120 arranged to face the light incident surface of the optical waveguide 110 focuses the incident light and provides it into the optical waveguide 110. For example, the optical coupling element 120 may be an optical element, such as a lens, that focuses light on the light incident surface of the optical waveguide 110. [ However, the optical coupling element 120 may be formed of a Fresnel lens, a diffractive optical element such as a slit, or a prism, in addition to a lens.

The light incident into the optical waveguide 110 propagates through the optical waveguide 110 through total reflection. 5, the optical waveguide 110 includes first and second clad layers 110a and 110c having relatively low refractive indexes, and a second clad layer 110b having a relatively lower refractive index than the first and second clad layers 110a and 110c. And a core layer 110b having a high refractive index. Then, according to the same principle as that of the optical waveguide including a general optical fiber, light can travel in the core layer 110b while being totally reflected at the interface between the core layer 110b and the first and second clad layers 110a and 110c have. Alternatively, the refractive index of the first and second clad layers 110a and 110c may be higher than that of the core layer 110b disposed therebetween. In this case, the refractive index of the core layer 110b Light can proceed inside. In either case, the core layer 110b may be composed of the nanostructured acousto-optic medium of the first and second acoustooptic elements 132 and 134, or the core layer 110b and the two cladding layers 110a and 110c ).

FIG. 6 is a cross-sectional view of the optical scanner 100 shown in FIG. 4 cut in a direction perpendicular to the light traveling direction, schematically showing a cross section of the first acoustooptic device 132 disposed in the optical waveguide 110. 6, a first acoustooptic device 132 disposed on an optical waveguide 110 on a substrate 101 includes a first medium 132a and a second medium 132b alternately arranged along a direction perpendicular to the traveling direction of light, 2 medium 132b. Here, the first and second media 132a and 132b may be identical to the media 11 and 12 already described with reference to FIG. However, the first acousto-optical element 132 may be formed according to the embodiment shown in Fig. In this case, the first and second media 132a and 132b may be arranged in the same direction as the media 13 and 14 already described with reference to FIG. 6, the first acousto-optical element 132 may be disposed only in the core layer 110b of the optical waveguide 110, but the core acute angle between the core layer 110b and the entire clad layers 110a and 110c As shown in FIG. In this structure, when a sound wave is applied along a direction perpendicular to the traveling direction of light through the side surface of the first acousto-optical element 132, the light can be diffracted and deflected in the horizontal direction. Although only the first acousto-optical element 132 is shown in Fig. 6, the above description can be similarly applied to the second acousto-optic element 134. Fig. However, the second acousto-optical element 134 is different in that it is arranged to deflect the light in the vertical direction.

Accordingly, the optical scanner 100 shown in FIG. 4 can deflect the incident light at a predetermined angle along the horizontal and vertical directions according to the voltages applied to the first sound wave generator 131 and the second sound wave generator 133 . In addition, by modulating the frequency of the AC voltage applied to the first sound wave generator 131 and the second sound wave generator 133, the incident light can be scanned in a horizontal and / or vertical direction within a predetermined angle range. Although the optical scanner 100 shown in FIG. 4 includes two acoustooptic elements 132 and 134, it may include only one acoustooptic element scanning light only in the horizontal or vertical direction, And may include a plurality of acousto-optic elements for scanning light in one direction.

The optical scanner 100 shown in Fig. 4 can be applied to a laser image projection apparatus. For example, as shown in FIG. 7, displaying an image by scanning red laser light, green laser light, and blue laser light on the screen 200 with three optical scanners 100R, 100G, and 100B, respectively It is possible. Instead of using three optical scanners 100R, 100G, and 100B, a laser image projection apparatus can be implemented with only one optical scanner. For example, as shown in FIG. 8, the red laser light, the green laser light, and the blue laser light can be scanned by the optical scanner 100 according to a time sequence. That is, while displaying an image of one frame, red laser light is scanned during the first 1/3 of one frame period (T seconds) (i.e., during T / 3 seconds), and green laser light And scan the blue laser light for the last 1/3 period. Then, only one optical scanner 100 can display an image. In this case, a light incidence structure may be formed such that laser beams of respective colors are incident on the optical scanner 100 at different angles.

In addition, the acousto-optic devices 10 and 20 shown in Figs. 1 and 3 can be applied to a 2D / 3D converted stereoscopic image display device. 9 schematically shows an example in which the acousto-optic devices 10 and 20 shown in Figs. 1 and 3 are applied to a 2D / 3D converted stereoscopic image display device. For example, a plurality of acousto-optic elements 210 having the same width as the pixels of the display panel 200 and extending in the transverse direction are manufactured, and a plurality of acousto-optical elements 210 are arrayed along the longitudinal direction The display panel 200 can be arranged on the surface of the display panel 200. Then, one acousto-optic element 210 may correspond to one pixel row of the display panel 200.

If no sound waves are applied to the array of such acousto-optic elements 210, the image displayed on the display panel 200 passes through the array of acoustooptic elements 210 as it is without being deflected. In this case, as shown in the left side of Fig. 9, the display device can operate in the 2D display mode. On the other hand, in the multi-viewpoint and stereoscopic 3D display mode, each acoustooptic element 210 generates a beam of multi-directional information, and the viewer can appreciate the 3D image as shown on the right side of FIG.

The acousto-optic elements 10 and 20 shown in FIGS. 1 and 3 are also applicable to a holographic 3D display device. Fig. 10 schematically shows an example in which the acousto-optic elements 10 and 20 shown in Figs. 1 and 3 are applied to the holographic 3D display device 300. Fig. 10, the holographic 3D display device 300 may include a light source 310, an array of a plurality of acousto-optical elements 320, and a projection optical system 330. [ Light source 310 may be, for example, an array of multiple lasers. In addition, the array of the plurality of acousto-optic devices 320 may include a plurality of acousto-optic devices 320 that are elongated in the transverse direction, and the plurality of acousto-optical devices 320 may be arrayed along the longitudinal direction Or the like. At this time, one acousto-optic element 320 may correspond to one horizontal direction hologram row of the hologram image displayed in the holographic display device 300. The hologram rows diffracted from the plurality of acousto-optic devices 320 can be projected onto a predetermined space by the projection optical system 330 to form one stereoscopic image.

Up to now, to facilitate the understanding of the present invention, an exemplary embodiment of a nanostructured acousto-optic element and an optical scanner, an optical modulator and a holographic display apparatus using the acoustooptic element have been described and shown in the accompanying drawings. It should be understood, however, that such embodiments are merely illustrative of the present invention and not limiting thereof. And it is to be understood that the invention is not limited to the details shown and described. Since various other modifications may occur to those of ordinary skill in the art.

10, 20, 132, 134, 210, 320 ..... acousto-optic element
30, 40 ..... nano structured acousto-optic medium
11, 12, 13, 14, 132a, 132b ..... medium
15, 131, 133 ..... sound wave generator
100, 100R, 100G, 100B ..... optical scanner
101 .... substrate 110 ..... optical waveguide
110a, 110c ..... Cladding layer 110b .... Core layer
120 ..... optical coupling element 200 ..... display panel
300 ..... Holographic display device 310 ..... Light source
330 ..... projection optical system

Claims (25)

A plurality of first medium and second medium having different permittivities arranged alternately and repeatedly;
At least one additional medium that alternately repeats with the first and second media and has a dielectric constant different from that of the first and second media; And
And an acoustic wave generator for applying a sound wave to the first medium, the second medium, and the at least one additional medium,
Wherein the first medium is made of an acousto-optic medium and the second medium is made of a material whose real part of dielectric constant is negative,
The period in which the first medium, the second medium, and the at least one additional medium alternate is less than the wavelength of the incident light,
Wherein the first medium, the second medium, and the at least one additional medium are repeatedly arranged along the traveling direction of the sound waves applied by the sound wave generator,
Wherein the acousto-optic element is configured to diffract light transmitted through the acoustooptic element,
Wherein the acousto-optic element is configured to diffract incident light incident in a direction transverse to a direction in which the first medium, the second medium, and the at least one additional medium are arranged. delete The method according to claim 1,
And the sound wave generator is disposed on one surface of the first medium. The method according to claim 1,
Wherein the material in which the real part of the dielectric constant is negative is at least one of Al, Ag, Au, Cu, Na, Ka, ITO, AZO, GZO and graphene. The method according to claim 1,
Wherein at least one of the first medium, the second medium and the at least one additional medium comprises at least one of GaN, Al _1-x Ga _x N, In _1-x Ga _x N, ZnO, . delete delete The method according to claim 1,
Wherein the first medium and the second medium have different real part signs of the dielectric constant. delete The method according to any one of claims 1, 3, 4, 5, and 8,
Wherein the acousto-optic element is an optical modulator for amplitude-modulating incident light. Optical waveguide;
A light coupling element for making light incident on the optical waveguide;
A first acousto-optical element according to any one of claims 1 to 7, arranged to deflect light in the optical waveguide in a first direction; And
A second acousto-optic element according to any one of claims 1 to 9, arranged to deflect light in the optical waveguide in a second direction perpendicular to the first direction; . 12. The method of claim 11,
Wherein the optical scanner further comprises a substrate, wherein the optical waveguide is disposed within the substrate. 13. The method of claim 12,
Wherein the first acoustooptic element comprises a first sonic wave generator and the second acoustooptic element comprises a second sonic wave generator wherein the first sonic wave generator and the second sonic wave generator are respectively connected to the first acousto- And is disposed on the upper surface of the substrate so as to be adjacent to the side of the two acoustooptic element. 12. The method of claim 11,
Wherein the optical coupling element is arranged to face the light incident surface of the optical waveguide so as to focus the incident light and to provide the optical waveguide in the optical waveguide. 15. The method of claim 14,
Wherein the optical coupling element is a lens. 12. The method of claim 11,
Wherein the optical waveguide includes first and second clad layers having relatively low refractive indexes and a core layer disposed between the first and second clad layers and having a relatively high refractive index. 17. The method of claim 16,
Wherein the first and second acousto-optic elements are disposed in a core layer of the optical waveguide. 12. The method of claim 11,
Wherein the optical waveguide includes first and second clad layers having relatively high refractive indexes and a core layer disposed between the first and second clad layers and having a relatively low refractive index. 19. The method of claim 18,
Wherein the first and second acousto-optic elements are disposed in a core layer of the optical waveguide. A display panel; And
And an acoustooptic device array disposed on a front surface of the display panel for deflecting an image displayed on the display panel,
Wherein the acousto-optic element array includes a plurality of acousto-optic elements according to any one of claims 1, 3, 4, 5, and 8. 21. The method of claim 20,
Each of the acousto-optic elements of the acousto-optic element array is elongated in the transverse direction and a plurality of acousto-optical elements are arranged along the longitudinal direction. 22. The method of claim 21,
And one acousto-optical element corresponding to one pixel row of the display panel. A light source for providing light;
An acousto-optical element array comprising a plurality of acousto-optic elements according to any one of claims 1 to 7 for deflecting light provided from a light source; And
And a projection optical system for projecting the light deflected by the acousto-optic element array. 24. The method of claim 23,
Wherein each of the acousto-optic elements of the acousto-optic element array is elongated in the transverse direction, and a plurality of acousto-optic elements are arranged in the longitudinal direction. 25. The method of claim 24,
Wherein one acousto-optic element corresponds to one horizontal hologram row of a hologram image displayed in the holographic display device.

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