KR20160066942A - Apparatus and method for manufacturing Holographic Optical Element - Google Patents

Apparatus and method for manufacturing Holographic Optical Element Download PDF

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Publication number
KR20160066942A
KR20160066942A KR1020140172385A KR20140172385A KR20160066942A KR 20160066942 A KR20160066942 A KR 20160066942A KR 1020140172385 A KR1020140172385 A KR 1020140172385A KR 20140172385 A KR20140172385 A KR 20140172385A KR 20160066942 A KR20160066942 A KR 20160066942A
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KR
South Korea
Prior art keywords
optical element
lens array
reference beam
recording medium
holographic optical
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KR1020140172385A
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Korean (ko)
Inventor
이병호
홍기훈
염지운
장창원
이강
Original Assignee
서울대학교산학협력단
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Priority to KR1020140172385A priority Critical patent/KR20160066942A/en
Publication of KR20160066942A publication Critical patent/KR20160066942A/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/10—Processes or apparatus for producing holograms using modulated reference beam
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S359/00—Optical: systems and elements
    • Y10S359/90—Methods

Abstract

Provided are an apparatus and a method for manufacturing a holographic optical element which are capable of displaying a two- or three-dimensional image. The apparatus for manufacturing a holographic optical element includes a light radiation unit; a beam splitter for dividing a laser beam from the light radiation unit into a signal beam and a reference beam; a reference beam optical system for irradiating the reference beam to a holographic material; a lens array including a plurality of elemental lenses; and a signal beam optical system for radiating the signal beam to the lens array. An interference fringe of the signal beam, which is modified through the reference beam and the lens array, is recorded on the holographic material.

Description

[0001] The present invention relates to a method and an apparatus for manufacturing a holographic optical element,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to a method and apparatus for manufacturing a holographic optical element and, more particularly, to a method of recording the optical characteristics of a lens array including a plurality of elemental lenses in a holographic optical element And apparatus.

Recently, there has been a great demand for a three-dimensional image display device capable of realizing images more effectively and effectively in various fields such as movies, games, advertisements, medical images, education, and military. Accordingly, various techniques for displaying three-dimensional images have been proposed, and various types of three-dimensional image display devices have already been commercialized.

For example, the three-dimensional image display device includes a spectacle method and a non-spectacle method. In the stereoscopic method, there are a lenticular method using a plurality of cylindrical lens arrays and a parallax barrier method having a plurality of openings and openings. have.

A hologram method and an integrated image method have been proposed as a three-dimensional image display method in which the depth perception recognized by the brain matches the focal point of the eye and can provide full parallax.

A hologram is a medium on which a light wave is recorded, and stores intensity and phase information of the light wave. While ordinary photographs only record intensity information, holograms store both intensity and phase, enabling three-dimensional reconstruction of visual information. For the recording of the hologram, two beams including a signal beam having a coherence and a reference beam are required. The signal beam is a beam that can be modulated from the object to be recorded. The intensity or phase information of the interference fringe between the signal beam and the reference beam can be recorded in the hologram recording medium to record the intensity and phase information of the modulated signal beam. When a beam having the same optical characteristic as the reference beam used for recording is incident on the recorded hologram, the signal beam stored in the hologram can be reproduced.

The integral imaging technique is a method of non-spectacular three-dimensional display, which provides both vertical and horizontal parallax using a lens-array to provide three-dimensional images to viewers without special glasses There is a way. Each element lens constituting the lens array can display a three-dimensional virtual image before or after the integrated image display by adjusting the optical information distribution of the specially produced element image. The lens array can be used as a lens assembly having a two-dimensional periodic arrangement, in addition to an integrated image, a two-dimensional image screen, a light distribution control, and the like.

According to these embodiments, a holographic optical element in which the optical characteristics of a lens array including a plurality of element lenses are recorded is generated, and a method and an apparatus for manufacturing a holographic optical element for displaying a two-dimensional or three-dimensional image to provide.

An apparatus for manufacturing a holographic optical element according to a first aspect includes: a light irradiation unit; A beam splitter for separating the laser beam from the light irradiating unit into a signal beam and a reference beam; A reference beam optical system for irradiating the reference beam to a holographic material; A lens array including a plurality of elemental lenses; And a signal beam optical system for irradiating the signal beam to the lens array, and an interference pattern of the signal beam modulated through the reference beam and the lens array can be recorded in the hologram recording medium.

Further, an apparatus for manufacturing a holographic optical element includes a plurality of light sources emitting laser beams of different wavelengths; A plurality of mirrors for superposing laser beams of different wavelengths into a beam having one path; A shutter for determining an exposure time of the superimposed beam; And a beam expander for expanding the width of the superimposed beam.

The reference beam optical system further includes: a first mirror for reflecting the reference beam such that the reference beam is irradiated at an angle defined by the hologram recording medium; And a first aperture for adjusting an area irradiated with the reference beam onto the hologram recording medium.

The signal beam optical system further includes: a second mirror that reflects the signal beam such that the signal beam is irradiated in a direction perpendicular to the lens array; And a second diaphragm for adjusting an area irradiated with the reference beam to the lens array.

The apparatus for manufacturing a holographic optical element may further include a stage on which the hologram recording medium is disposed and on which a position of an area of the hologram recording medium on which the interference fringe is recorded is changed to change.

Further, the interference fringes may occur when the reference beam and the modulated signal beam cross each other through the opposite surfaces of the hologram recording medium.

According to the second aspect, a holographic optical element can record an interference pattern of a signal beam modulated through a lens array including a reference beam and a plurality of elemental lenses, Dimensional or three-dimensional image can be selectively displayed according to the size of pixels in the image.

When the size of the pixels in the image is smaller than the size of each of the element lenses, the holographic optical element displays a two-dimensional image. If the size of each element lens is larger than twice the size of the pixels in the image, A three-dimensional image can be displayed.

In addition, the holographic optical element can display a two-dimensional or three-dimensional image in full color.

According to a third aspect, a method of manufacturing a holographic optical element includes: emitting a laser beam; Separating the laser beam into a signal beam and a reference beam; Irradiating the reference beam to a holographic material; Irradiating the signal beam to a lens array including a plurality of elemental lenses; And recording interference fringes of the signal beam modulated through the reference beam and the lens array on the hologram recording medium.

Also, a manufacturing method of a holographic optical element includes: emitting laser beams of different wavelengths; Superposing laser beams of different wavelengths into a beam having one path; And expanding the width of the superimposed beam.

Further, the step of irradiating the reference beam includes the steps of: reflecting the reference beam such that the reference beam is irradiated at an angle defined by the hologram recording medium; And adjusting an area irradiated with the reference beam onto the hologram recording medium.

The step of irradiating the signal beam further includes the steps of: reflecting the signal beam such that the signal beam is radiated in a direction perpendicular to the lens array; And adjusting an area where the reference beam is irradiated to the lens array.

Further, the manufacturing method of the holographic optical element may further include: changing the position of the area of the hologram recording medium on which the interference fringes are recorded.

Further, the interference fringes may occur when the reference beam and the modulated signal beam cross each other through the opposite surfaces of the hologram recording medium.

According to embodiments of the present invention, the holographic optical element according to the present disclosure is effective to realize optical see-through augmented reality.

Further, according to embodiments of the present invention, the holographic optical element can selectively display a two-dimensional or three-dimensional image according to the size of a pixel in an image incident on the holographic optical element.

Further, according to embodiments of the present invention, the holographic optical element can display a full-color two-dimensional or three-dimensional image.

The present invention may be readily understood by reference to the following detailed description and the accompanying drawings, in which reference numerals refer to structural elements.
1 is a view for explaining an apparatus for manufacturing a holographic optical element according to the present disclosure.
2 is a diagram for explaining a process of recording an interference pattern of a signal beam modulated through a reference beam and a lens array on a hologram recording medium according to an embodiment.
3 is a view for explaining an apparatus for manufacturing a holographic optical element according to an embodiment.
4 is a diagram for explaining a two-dimensional or three-dimensional display device according to an embodiment.
Fig. 5 is a diagram for explaining contents in which a holographic optical element receives light for displaying an image from the outside and reproduces the image, according to an embodiment. Fig.
6A and 6B are views for explaining contents in which a holographic optical element displays a two-dimensional or three-dimensional image on a space, according to an embodiment.
7 shows an example in which a holographic optical element displays a three-dimensional image, according to one embodiment.
8 shows an example in which a holographic optical element displays a two-dimensional image, according to one embodiment.
9 is a view for explaining a method of manufacturing a holographic optical element, according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are intended to illustrate the invention and are not intended to limit or limit the scope of the invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

When an element is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements as well, without departing from the spirit or scope of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. In order to clearly explain the present invention in the drawings, parts not related to the description will be omitted.

1 is a view for explaining an apparatus 100 for manufacturing a holographic optical element (hereinafter referred to as apparatus 100) according to the present disclosure.

The apparatus 100 may include a light illuminating unit 110, a beam splitter 120, a reference beam optical system 130, a lens-array 150, And a signal beam optical system 140. The apparatus 100 shown in FIG. 1 is only shown in the components associated with this embodiment. Therefore, it will be understood by those skilled in the art that other general-purpose components other than the components shown in FIG. 1 may be further included.

The light irradiating unit 110 may emit a laser beam B, according to an embodiment. The light irradiating unit 110 may emit a laser beam B in which beams of different wavelengths are overlapped, according to an embodiment. In addition, the light irradiating unit 110 may alternately emit beams of different wavelengths according to different viewpoints. A more detailed description will be given in Fig.

The beam splitter 120 can separate the laser beam B emitted from the light irradiation unit 110 into the signal beam S and the reference beam R, according to an embodiment. According to one embodiment, the beam splitter 120 may be a half mirror, allowing approximately 50% of the incident beam to be transmitted and used as the signal beam S, 50% of the reference beam R is reflected. 1, the light transmitted through the beam splitter 120 becomes the signal beam S, and the light reflected by the beam splitter 120 is shown as the reference beam R, which is an exemplary one. For example, in an alternative embodiment, the light transmitted through the beam splitter 120 may be a reference beam R, and the light reflected by the beam splitter 120 may be a signal beam S, The layout can be changed.

The reference beam optical system 130 may irradiate the reference beam R with a predefined angle? To the hologram material 160, according to one embodiment. The reference beam optical system 130 may include a mirror 132 and a diaphragm 134, according to one embodiment. The mirror 132 may reflect the reference beam R such that the reference beam R from the beam splitter 120 is irradiated at an angle? Defined by the hologram recording medium 160. [ According to one embodiment, the mirror 132 can adjust the predefined angle [theta]. The numerical value of the predefined angle [theta] is used to determine the angle of the image to be incident on the holographic optical element when two- or three-dimensional images are displayed using the holographic optical element produced by the apparatus 100 Can be used. The diaphragm 134 can adjust the area irradiated to the hologram recording medium 160 by the reference beam R reflected from the mirror 132. The hologram recording medium 160 may be a silver halide, a photorefractive polymer, a photopolymer, or the like. According to one embodiment, the apparatus 100 may use a photopolymer favorable for wavelength multiplexing in the holographic recording medium 160 in total full-color recording.

The lens array 150, according to one embodiment, may be composed of a plurality of elemental lenses. The lens array 150, in accordance with one embodiment, may be configured in a two-dimensional array and may perform various functions. For example, the lens array 150 may function as a diffuser for two-dimensional image reproduction, may be used for uniform illumination, and may be used for light control . The lens array 150 may also function as an optical element for an autostereoscopic three-dimensional image, to display a three-dimensional integrated image, according to one embodiment.

The signal beam optical system 140 can irradiate the lens array 150 with the separated signal beam S, according to one embodiment. According to one embodiment, the signal beam optics 140 may illuminate the signal beam in a direction perpendicular to the lens array 150. [ The signal beam optics 140 may include a mirror 142 and a diaphragm 144, according to one embodiment. The mirror 142 can reflect the signal beam S such that the signal beam S from the beam splitter 120 is directed in a direction perpendicular to the lens array 150. [ The diaphragm 144 can adjust the area irradiated with the signal beam S reflected from the mirror 142 onto the lens array 150. [

The signal beam S reflected from the mirror 142 can be modulated while transmitting through the lens array 150. [ The reference beam R reflected from the mirror 142 and the signal beam S modulated through the lens array 150 can meet with each other to form an interference fringe and the formed interference fringe is recorded on the hologram recording medium 160 .

According to one embodiment, the apparatus 100 records interference fringes of a signal beam modulated through a reference beam R and a lens array 150 onto a hologram recording medium 160 to generate a holographic optical element . That is, the holographic optical element means a hologram recording medium in which an interference fringe of a signal beam modulated through a reference beam R and a lens array 150 is recorded. Accordingly, the apparatus 100 can produce a holographic optical element by recording an interference pattern of a signal beam modulated through the reference beam R and the lens array 150 on a hologram recording medium, May include the optical characteristics of the array 150. For example, the holographic optical element, like the lens array 150, can function as a diffuser for two-dimensional image reproduction and can be used for uniform illumination, and can function as an optical element for an autostereoscopic three-dimensional image to display a three-dimensional integrated image.

1, the apparatus 100 uses the reflection type hologram recording method in which the signal beam S and the reference beam R are incident on each of both surfaces of the hologram recording medium 160. However, The apparatus 100 may use a transmissive hologram recording method in which the signal beam S and the reference beam R are incident on one surface of the hologram recording medium 160, respectively.

FIG. 2 is a diagram for describing in more detail a process in which an interference fringe of a signal beam modulated through a reference beam and a lens array is recorded on a hologram recording medium, according to an embodiment.

As shown in FIG. 2, the reference beam is irradiated onto the hologram recording medium 220 as a plane-wave. The signal beam of the plane wave passes through the lens array 210 and is modulated into a spherical wave having the optical characteristic of the lens array 210 and is irradiated to the hologram recording medium 220. The reference beam and the modulated signal beam meet each other to form an interference fringe, and the formed interference fringe is recorded in the hologram recording medium 220. [ The hologram recording medium 220 on which the interference fringe is recorded may mean a holographic optical element.

3 is a view for explaining an apparatus 300 for manufacturing a holographic optical element (hereinafter, referred to as apparatus 300) according to an embodiment.

Apparatus 300 may include a light irradiating unit 310, a beam splitter 320, a reference beam optical system 330, a lens-array 340, A signal beam optical system 350 and a stage 360. The device 300 shown in FIG. 3 is only shown in the components associated with this embodiment. Therefore, it will be understood by those skilled in the art that other general-purpose components other than the components shown in FIG. 3 may be further included.

The beam splitter 320, the reference beam optical system 330, the lens array 340, the signal beam optical system 350, and the hologram recording medium 370 of FIG. 3 include the contents described in FIG. 1, The description will be omitted.

The light irradiating unit 310 includes a plurality of laser light sources 311, 312 and 313, a half wave plate 314 corresponding to each of the plurality of laser light sources 311, 312 and 313, a plurality of laser light sources A neutral density filter 315 corresponding to each of the plurality of laser light sources 311, 312 and 313, mirrors 316, a shutter 317 and a beam expanding unit 316 corresponding to the plurality of laser light sources 311, 312 and 313, ) 318. < / RTI >

The plurality of laser light sources 311, 312, and 313 may emit laser beams having different wavelengths according to an embodiment. Each of the plurality of laser light sources 311, 312, and 313 may be a laser light source that outputs coherent light or a laser light source that emits a continuous wave (CW) laser or a quasi-CW laser . For example, the laser light source 311 can emit a red laser beam having a wavelength of 671 nm, the laser light source 312 can emit a green laser beam having a wavelength of 532 nm, and the laser light source 313 A blue laser beam having a wavelength of 473 nm can be emitted. In addition, each of the plurality of laser light sources 311, 312, and 313 may emit laser beams of different wavelengths at the same time or alternately.

The plurality of half wave plates 314 are disposed along the path of the laser beams emitted from the plurality of laser light sources 311, 312 and 313, respectively, according to an embodiment, and can adjust the polarization states of the respective laser beams.

The ND filter 315 lies in the path of the laser beams emitted from the plurality of laser light sources 311, 312 and 313, respectively, according to one embodiment, and can control the power density of the respective laser beams. The apparatus 300 can adjust the power density of each laser beam through the ND filter 315 such that the holographic optical element has a similar diffraction efficiency according to a particular wavelength of light incident on the holographic optical element can do.

The mirrors 316 may reflect the laser beams so that the laser beams respectively emitted from the plurality of laser light sources 311, 312, and 313 can be superimposed on one beam, according to one embodiment.

Shutter 317 may, in accordance with one embodiment, determine the exposure time of the superimposed beam.

The beam expander 318 may extend the overlapped beam width and, in accordance with one embodiment, enable the overlapped beam to satisfy a collimated plane wave condition. According to one embodiment, beam expander 318 may include an objective lens, a pinhole, and a collimating lens.

The stage 360 can be arranged so that the hologram recording medium 370 is placed on the stage 360 so as to further expand the recordable area of the hologram recording medium 370 according to one embodiment and the stage 360 Can be moved as an electric motor. According to one embodiment, the stage 360 may be one-axis or two-axis linear movement. Also, according to one embodiment, the stage 360 may include a drive control (not shown) for controlling the movement of the stage 360. The apparatus 300 may enable spatial multiplexing using the stage 360 so that the size of the holographic optical element that can be manufactured is not limited, The size of the device can be increased.

According to one embodiment, the reference beam and the holographic optical element on which the interference fringes of the signal beam modulated through the lens array are recorded may have the same optical characteristics as the lens array. That is, the holographic optical element, according to one embodiment, can function as a diffuser for two-dimensional image reproduction, like a lens array, and can be used for uniform illumination, Can be used for control. The holographic optical element may also function as an optical element for an autostereoscopic three-dimensional image, to display a three-dimensional integrated image, according to one embodiment.

In addition, the apparatus 300 records interference fringes of the reference beam and the signal beam on the hologram recording medium with laser beams according to different wavelengths, so that wavelength multiplexing is possible. Accordingly, the holographic optical element manufactured by the apparatus 300 can display a two-dimensional or three-dimensional image of total color.

In addition, the holographic optical element according to the present disclosure has a characteristic of a volume hologram, so that it is very excellent in the selectivity of the angle, so that it is possible to have a characteristic that the brightness drop of the external real world image is very small.

Therefore, in the following, contents for displaying a two-dimensional or three-dimensional image through the holographic optical element recorded by the above-described method will be described.

4 is a diagram for explaining a two-dimensional or three-dimensional display device 400 (hereinafter referred to as a device 400) according to an embodiment.

Apparatus 400 may include a projector 410 and a holographic optical element 420, according to one embodiment. The device 400 shown in FIG. 4 is only shown in the components associated with this embodiment. Accordingly, it will be understood by those skilled in the art that other general-purpose components other than the components shown in FIG. 4 may be further included.

The projector 410 may project light for displaying an image onto the holographic optical element 420, according to one embodiment. The projector 410 may be used to satisfy the Bragg's matching condition because the reference beam used in the recording step of the holographic optical element 420 is a collimated light in accordance with one embodiment, A collimated light can be projected onto the holographic optical element 420. [ Bragg matching means that a hologram recorded with a reference beam and a signal beam having a specific angle of incidence depends strongly on the angle between the reference beam at the time of recording and the beam at the time of reconstruction. That is, for example, since the reference beam is incident at an angle of &thetas; in the recording step of the holographic optical element 420, the projector 410 projects the parallel light to the holographic optical element 420 at an angle & can do.

The projector 410 also includes a telecentric lens (not shown) and relay optics (not shown) to project the collimated light to the holographic optical element 420, according to one embodiment Time). The diverging angle of the parallel light projected by the projector 410 can be adjusted by relay optics (not shown). However, if a diverging reference beam is used in the recording step of the holographic optical element 420, a telecentric lens (not shown) may be omitted.

In addition, the projector 410 may project elemental images for displaying a three-dimensional image or a two-dimensional image for displaying a two-dimensional image on the holographic optical element 420, according to an embodiment .

The holographic optical element 420 may selectively display a two-dimensional or three-dimensional image on the space, based on the light or image input from the projector 410, according to one embodiment.

The holographic optical element 420 may, according to one embodiment, be a holographic optical element manufactured according to FIGS. That is, the holographic optical element 420 may refer to a hologram recording medium in which interference fringes of a signal beam modulated through a reference beam and a lens array are recorded.

FIG. 5 is a diagram for explaining contents in which a holographic optical element 510 receives light for displaying an image from the outside and displays an image, according to an embodiment.

The holographic optical element 510 may, according to one embodiment, receive light that satisfies Bragg matching conditions with the reference beam that was used in the recording step of the holographic optical element 510. The holographic optical element 510 can restore the spherical wave based on the light satisfying the Bragg matching condition. In addition, the holographic optical element 510 may refer to a hologram recording medium in which interference fringes of a signal beam modulated through a reference beam and a lens array are recorded. Therefore, the holographic optical element 510, like the lens array, can restore the spherical wave based on the light satisfying the Bragg matching condition. Therefore, the observer can see the image displayed on the space through the restored spherical wave.

The holographic optical element 420 of FIG. 4 may display a two-dimensional or three-dimensional image in space according to the size of a pixel in an image input from the outside, according to an embodiment. According to one embodiment, in the holographic optical element 420 having the optical characteristics of the lens array, the size of the pixels in the image that is perpendicular to the holographic optical element 420 is smaller than the lens size of the element lenses constituting the lens array If the size is smaller, the holographic optical element 420 can display a two-dimensional image. Further, according to one embodiment, in the holographic optical element 420 having the optical characteristics of the lens array, twice the size of the pixels in the image perpendicularly incident on the holographic optical element 420 constitutes the lens array Is greater than the lens size of the element lenses, the holographic optical element 420 can display a three-dimensional image. Further, if the image is incident on the holographic optical element 420 at a specific angle?, The size of a pixel of an image incident at a specific angle? Is scaled by a vertical component of the pixel size .

6A and 6B are views for explaining contents in which a holographic optical element displays a two-dimensional or three-dimensional image on a space, according to an embodiment.

6A and 6B, for convenience of description, a lens array is shown inside the holographic optical elements 610 and 620 to represent the holographic optical elements 610 and 620 having the optical characteristics of the lens array.

6A and 6B, the traveling direction of the image projected by the projectors 615 and 625 is expressed as being parallel to the optical axis of the lens array, and is projected with different color and intensity information The pixels are expressed as P 1 , P 2 , P 3 .

6A is a diagram for explaining an example in which the holographic optical element 610 displays a two-dimensional image as a two-dimensional image screen.

6A, pixels P 1 , P 2 , P 3 having the same size as the size of each element lens of the lens array are projected onto the holographic optical element 610. Each of the pixels P 1 , P 2 , and P 3 transmits through the holographic optical element 610 and diverges at an angle equal to the numerical aperture of the element lens. Therefore, the observer can observe the two-dimensional image within the diffusion angle.

6B shows each element lens of the lens array which is three times larger than the size of each of the pixels P 1 , P 2 and P 3 . Each of the pixels P 1 , P 2 , and P 3 passes through the holographic optical element 620, crosses at the same focal point, and then diffuses in different directions according to the refracting direction. Therefore, the observer sees a non-spectacular three-dimensional image having a viewing angle corresponding to the same numerical aperture of the urea lens.

Therefore, the holographic optical element 420 of FIG. 4 can display a two-dimensional or three-dimensional image based on an image that is incident with the same wavelength and the same incident angle as the reference beam used for recording. That is, the holographic optical element 420 can display a two-dimensional or three-dimensional image according to the relative difference between the pixel size of the image satisfying the Bragg matching condition and the size of the element lens of the lens array.

4, the holographic optical element 420 displays a two-dimensional or three-dimensional image in a direction in which the projector 410 projects an image, and the observer 430 includes a projector 410, Dimensional or three-dimensional image in the direction in which the image is projected. In addition, the holographic optical element 420 in FIG. 4 is shown as having the feature of a reflective hologram, and it is shown that the observer 430 can view the image in the direction in which the projector 410 projected the image. Thus, if the holographic optical element 420 in FIG. 4 has the characteristics of a transmissive hologram, the observer 430 can view the two- or three-dimensional image in a direction opposite to the direction in which the projector 410 projected the image There will be.

In addition, the holographic optical element 420 has a property of transmitting light that does not satisfy the Bragg matching condition from the light incident on the holographic optical element 420 as it is, and has a see-through characteristic . Thus, the holographic optical element 420 can satisfy transparent conditions without degradation of real world brightness, which is an essential requirement in optical see-through augmented reality.

Thus, the holographic optical element 420 according to the present disclosure may be used in portable devices, head up display devices, 3D display devices, video screens, etc. that implement optical transparent augmented reality, according to one embodiment .

7 shows an example in which a holographic optical element displays a three-dimensional image, according to one embodiment.

The image 710 represents an elemental image for generating a three-dimensional image. The image 710 can be projected onto the holographic optical element and the pixel size of the image 710 is 0.025 times the element lens size of the holographic optical element. The image 710 contains information of three characters S, N, and U. The image 710 consists of red, green, and blue characters S, N, and U, respectively, to show that color representation and three-dimensional implementation are possible at the same time, and depth information of +30 mm, Have.

The image 720 represents a three-dimensional image displayed by the holographic optical element when the image 710 is projected onto the holographic optical element. The image 720 represents the views viewed from the five observer positions (Top, Center, Right, Left, and Bottom) to indicate that the three-dimensional image is displayed . As can be seen from the image 720, it can be seen that a three-dimensional image is displayed in that the parallax exists according to the color and position of each word. Further, in order to show that the holographic optical element represents an optical transparent augmented reality, in each of the images in the image 720, a paper box, which is an actual object disposed behind the holographic optical element, is displayed together with the three-dimensional image .

8 shows an example in which a holographic optical element displays a two-dimensional image, according to one embodiment.

The image 810 represents an image for generating a two-dimensional image. The image 810 may be projected onto the holographic optical element and the pixel size of the image 810 is greater than or equal to the element lens size of the holographic optical element. The image 810 is composed of three colors of red, green, and blue to prove that color representation and three-dimensional implementation are possible at the same time.

The image 820 represents a two-dimensional image displayed by the holographic optical element when the image 810 is projected onto the holographic optical element. Further, in order to show that the holographic optical element represents an optically transparent augmented reality, in each of the images in the image 820, a paper box, which is an actual object disposed behind the holographic optical element, is displayed together with the two-dimensional image .

9 is a diagram for explaining a method of manufacturing a holographic optical element performed by the apparatuses 100 and 300, according to an embodiment.

The method shown in FIG. 9 can be performed by each component of the apparatus 100, 300 of FIG. 1 or FIG. 3, and redundant descriptions are omitted.

In step S910, the apparatus 100, 300 may emit a laser beam, according to one embodiment.

Devices 100 and 300 may emit beams of different wavelengths, according to one embodiment. The apparatus 100, 300 may emit coherent light and may emit a continuous wave (CW) laser or a quasi-CW laser. For example, apparatus 100, 300 may emit a red laser beam having a wavelength of 671 nm and apparatus 100, 300 may emit a green laser beam having a wavelength of 532 nm and apparatus 100, 300) can emit a blue laser beam having a wavelength of 473 nm. In addition, the devices 100 and 300 may emit laser beams of different wavelengths simultaneously or alternately.

According to one embodiment, the apparatus 100, 300 may adjust the polarization state of the emitted laser beams. Apparatus 100,300 may also adjust the power density of the laser beams, according to one embodiment. The apparatus 100, 300 may adjust the power density of the laser beams so that the holographic optical element has a similar diffraction efficiency according to a specific wavelength of light incident on the holographic optical element. In addition, the apparatus 100, 300 can superimpose the emitted laser beams into one beam and determine the exposure time of the superimposed beam.

In addition, the apparatus 100, 300 may extend the overlapping beam width and allow the overlapping beam to satisfy a collimated plane wave condition, according to one embodiment.

In step S920, the apparatus 100, 300 may separate the emitted laser beam into a signal beam and a reference beam, according to one embodiment.

According to one embodiment, the apparatus 100, 300 can transmit approximately 50% of the emitted beam to a signal beam and reflect approximately 50% of the emitted beam to separate into a reference beam.

In step S930, the apparatus 100, 300 may illuminate the hologram recording medium with a separate reference beam, according to one embodiment.

According to one embodiment, the apparatus 100, 300 may illuminate the reference beam at a predefined angle to the hologram material. The hologram recording medium may be a silver halide, a photorefractive polymer, a photopolymer, or the like. According to one embodiment, the apparatus 100 may use a photopolymer as a holographic recording medium, which is advantageous for wavelength multiplexing in full-color recording.

In addition, the apparatus 100, 300 may reflect the reference beam such that the reference beam is irradiated at an angle predefined in the hologram recording medium. The predefined angle values can be used to determine the angle of incidence to the holographic optical element when displaying a two- or three-dimensional image using the holographic optical element produced by the apparatus 100, have.

In addition, the apparatus 100, 300 can adjust the area irradiated to the hologram recording medium by the reflected reference beam.

In step S940, the apparatus 100,300 may illuminate a separate signal beam to a lens array, according to one embodiment. The lens array, according to one embodiment, may be composed of a plurality of elemental lenses. The lens array, according to one embodiment, may be configured in a two-dimensional array and may perform various functions. For example, the lens array can function as a diffuser for two-dimensional image reproduction, can be used for uniform illumination, and can be used for light control. The lens array may also function as an optical element for an autostereoscopic three-dimensional image, to display a three-dimensional integrated image, according to one embodiment.

According to one embodiment, the apparatus 100, 300 may reflect a signal beam such that the signal beam is directed in a direction normal to the lens array.

In addition, the apparatus 100, 300 can adjust the area irradiated by the signal beam onto the lens array.

In step S950, the apparatus 100, 300, according to one embodiment, may write the interference pattern of the signal beam modulated through the reference beam and lens array to the hologram recording medium.

According to one embodiment, the signal beam can be modulated while transmitting through the lens array. The signal beam modulated through the reference beam and the lens array can pass through and cross the different sides of the hologram recording medium to form an interference fringe, and the apparatus 100, 300 can record the interference fringe formed on the hologram recording medium .

In addition, according to one embodiment, the apparatus 100, 300 may further include a hologram recording medium, which may be linear (one-axis) or two-axis (linear) in order to further expand the recordable area of the hologram recording medium. Can be moved.

Accordingly, the apparatus 100, 300 can record the interference pattern of the signal beam modulated through the reference beam R and the lens array to the hologram recording medium using the above-described method, thereby generating a holographic optical element have. That is, the holographic optical element means a hologram recording medium in which an interference fringe of a signal beam modulated through a reference beam R and a lens array is recorded.

The hologram generating method, apparatus, and holographic three-dimensional image display apparatus according to the present invention are not limited to the configuration and method of the embodiments described above, but the embodiments may be modified in various ways, All or some of the embodiments may be selectively combined.

 The specific implementations described in this embodiment are illustrative and do not in any way limit the scope of the invention. For brevity of description, descriptions of conventional electronic configurations, control systems, software, and other functional aspects of such systems may be omitted. Also, the connections or connecting members of the lines between the components shown in the figures are illustrative of functional connections and / or physical or circuit connections, which may be replaced or additionally provided by a variety of functional connections, physical Connection, or circuit connections.

In this specification (particularly in the claims), the use of the terms "above" and similar indication words may refer to both singular and plural. In addition, when a range is described, it includes the individual values belonging to the above range (unless there is a description to the contrary), and the individual values constituting the above range are described in the detailed description. Finally, if there is no explicit description or contradiction to the steps constituting the method, the steps may be performed in an appropriate order. It is not necessarily limited to the description order of the above steps. The use of all examples or exemplary terms (e. G., The like) is merely intended to be illustrative of technical ideas and is not to be limited in scope by the examples or the illustrative terminology, except as by the appended claims. It will also be appreciated by those skilled in the art that various modifications, combinations, and alterations may be made depending on design criteria and factors within the scope of the appended claims or equivalents thereof.

Claims (15)

In an apparatus for manufacturing a holographic optical element,
A light irradiation unit;
A beam splitter for separating the laser beam from the light irradiating unit into a signal beam and a reference beam;
A reference beam optical system for irradiating the reference beam to a holographic material;
A lens array including a plurality of elemental lenses; And
And a signal beam optical system for irradiating the signal beam to the lens array,
And an interference fringe of the signal beam modulated through the reference beam and the lens array is recorded in the hologram recording medium. The method according to claim 1,
The light-
A plurality of light sources emitting laser beams of different wavelengths;
A plurality of mirrors for superposing the laser beams of the different wavelengths into a beam having one path;
A shutter for determining an exposure time of the superimposed beam; And
And a beam expander to expand the width of the superimposed beam. The method according to claim 1,
The reference beam optical system includes:
A first mirror for reflecting the reference beam such that the reference beam is irradiated at an angle defined by the hologram recording medium; And
And a first aperture for adjusting the area irradiated by the reference beam onto the hologram recording medium. The method according to claim 1,
The signal beam optical system includes:
A second mirror for reflecting the signal beam such that the signal beam is irradiated in a direction perpendicular to the lens array; And
And a second aperture for adjusting the area irradiated by the signal beam to the lens array. The method according to claim 1,
Further comprising: a stage in which the hologram recording medium is disposed and moving so as to change a position of an area in the hologram recording medium on which the interference fringes are recorded. The method according to claim 1,
Wherein the interference fringe is generated by crossing the reference beam and the modulated signal beam through mutually opposite surfaces of the hologram recording medium. 1. A holographic optical element in which interference fringes of a signal beam modulated through a lens array including a reference beam and a plurality of elemental lenses are recorded,
And selectively displays a two-dimensional or three-dimensional image according to a size of a pixel in an image incident from the outside to the holographic optical element. 8. The method of claim 7,
Dimensional image when the size of the pixel in the image is smaller than the size of each of the ellipses,
Dimensional image when the size of each of the element lenses is larger than twice the size of pixels in the image. 8. The method of claim 7,
Wherein the two-dimensional or three-dimensional image is displayed in full-color. In a method for manufacturing a holographic optical element,
Emitting a laser beam;
Separating the laser beam into a signal beam and a reference beam;
Irradiating the reference beam to a holographic material;
Irradiating the signal beam to a lens array including a plurality of elemental lenses; And
And recording the interference pattern of the signal beam and the signal beam modulated through the lens array in the hologram recording medium. 11. The method of claim 10,
Emitting laser beams of different wavelengths;
Overlapping the laser beams of the different wavelengths with a beam having one path; And
Further comprising: expanding the width of the superimposed beam. 11. The method of claim 10,
Wherein the step of irradiating the reference beam comprises:
Reflecting the reference beam such that the reference beam is irradiated at an angle predefined in the hologram recording medium; And
And adjusting an area of the reference beam irradiated on the hologram recording medium. 11. The method of claim 10,
Wherein the step of irradiating the signal beam comprises:
Reflecting the signal beam such that the signal beam is directed in a direction perpendicular to the lens array; And
And adjusting an area of the reference beam irradiated to the lens array. 11. The method of claim 10,
And changing the position of an area in the hologram recording medium on which the interference fringes are recorded. 11. The method of claim 10,
Wherein the interference fringe is generated by crossing the reference beam and the modulated signal beam through mutually opposite surfaces of the hologram recording medium.
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