CN106842568B

CN106842568B - Perspective type holographic display device and head mounted display device

Info

Publication number: CN106842568B
Application number: CN201610971761.0A
Authority: CN
Inventors: 成基荣; 金允泰; 安重权; 李泓锡
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2015-10-28
Filing date: 2016-10-28
Publication date: 2021-09-21
Anticipated expiration: 2036-10-28
Also published as: CN106842568A; KR102606340B1; KR20170049358A

Abstract

The invention provides a see-through type holographic display device and a head-mounted display device. The see-through type hologram display device includes a relay optical system which enlarges or reduces and transmits a hologram generated by a spatial light modulator; a noise removal filter that removes noise from diffracted light of the hologram transmitted via the relay optical system; and an optical path converter changing at least one of a path of the holographically diffracted light transmitted from the relay optical system and a path of the external light, thereby simultaneously or selectively seeing the hologram and the outside.

Description

Perspective type holographic display device and head mounted display device

Cross Reference to Related Applications

This application claims the benefit of korean patent application No.10-2015-0150272, filed on 28/10/2015 of the korean patent office, and korean patent application No.10-2016 0055766, filed on 4/5/2016 of the korean patent office, the disclosures of which are incorporated herein by reference.

Technical Field

The present disclosure relates to a holographic display device, and more particularly, to a see-through type holographic display device through which a hologram and an exterior are simultaneously or selectively seen.

Background

As many three-dimensional (3D) movies have been developed, research on technologies related to 3D image display devices has been conducted. For example, research into an apparatus for implementing a high-quality hologram in real time by using a Spatial Light Modulator (SLM) is actively performed.

Much research has recently been introduced into Head Mounted Displays (HMDs) and related products that implement Virtual Reality (VR). Large companies frequently occupy entrepreneurship companies with VR technology. However, conventional HMDs for VR are stereoscopic based techniques, which lead to visual fatigue due to the vergence adjustment conflict. Conventional HMDs for VR also cause a number of problems when applied to spatial interaction techniques.

Disclosure of Invention

A display device capable of implementing a perspective holographic three-dimensional (3D) image is provided.

A personal see-through 3D display Head Mounted Display (HMD) is provided.

According to an aspect of the present disclosure, there is provided a see-through type holographic display device including a light source providing light; a spatial light modulator for diffracting the light and reconstructing the hologram; a relay optical system that enlarges or reduces and transmits the hologram generated by the spatial light modulator; a noise removal filter that removes noise from diffracted light of the hologram transmitted via the relay optical system; and an optical path converter that changes at least one of a path of diffracted light of the hologram transmitted from the relay optical system and a path of external light, and transmits the diffracted light and the external light to the same area.

The see-through type holographic display device may further include: a collimator that converts light provided by the light source into collimated light.

The spatial light modulator may comprise an amplitude spatial light modulator, a phase spatial light modulator, or a complex spatial light modulator.

The relay optical system may include a first optical element to which the hologram modulated by the spatial light modulator is incident; and a second optical element having a second focal point on an incident surface side close to the first focal point on the emission surface side of the first optical element. The first optical element may have a first focal length and the second optical element may have a second focal length different from the first focal length. The noise removing filter may be disposed in the vicinity of the first focal point on the emission surface side of the first optical element. The noise-removal filter may include a pinhole.

The see-through type holographic display device may further include: and a field optical element focusing the hologram transmitted from the relay optical system.

The field optical element may be disposed near an image plane in which the hologram transmitted from the relay optical system is imaged. Alternatively, the field optical element may be arranged such that an image plane in which the hologram transferred from the relay optical system is imaged is located between a focal position on the incident surface side of the field optical element and the incident surface of the field optical element. The field optical elements may be arranged such that the image plane is re-imaged as an erect virtual image, the hologram transmitted from the relay optical system being imaged in the image plane.

The field optical element may be disposed adjacent to the light-path converter. The size of the hologram transmitted from the relay optical system can be adjusted by changing the distance between the relay optical system and the field optical element.

The optical path converter may include a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the third surface and transmitting at least a portion of the external light transmitted through the second surface to the third surface, the field optical element including an objective lens disposed adjacent to the first surface of the optical path converter.

The light path converter may include a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, a fourth surface opposite to the first surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the fourth surface, reflecting again at least a portion of the diffracted light of the hologram transmitted through the fourth surface to the third surface, and transmitting at least a portion of the external light transmitted through the second surface to the third surface, the field optical element including a concave mirror disposed adjacent to the fourth surface of the light path converter.

The light-path converter may include a half mirror, and the field optical element is located between the relay optical system and the light-path converter, adjacent to the light-path converter.

The light path converter may include a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the third surface and transmitting at least a portion of the external light transmitted through the second surface to the third surface, wherein the beam separating film has a concave curved surface shape with respect to the first surface to reflect and focus the hologram transmitted from the relay optical system to the third surface.

The beam splitting film may be a polarization selective reflective film.

The light path converter may be arranged such that the beam splitting film is disposed in the vicinity of an image plane on which the hologram transmitted from the relay optical system is imaged.

The see-through type holographic display device may further include a beam selective optical element that focuses diffracted light and transmits external light therethrough. The beam selective optical element may be a cemented lens having an isotropic lens and an anisotropic lens, wherein the cemented lens has a positive (+) value with respect to a refractive power of diffracted light, and a total refractive power of the cemented lens with respect to external light is zero. The beam selective optical element may include first and second transparent substrate layers facing each other and a liquid crystal layer interposed between the first and second transparent substrate layers, and selectively have a polarization characteristic by controlling the liquid crystal layer with an electrode disposed on at least one surface of the first and second transparent substrate layers. The beam selective optical element may include first and second transparent substrate layers opposite to each other and a liquid crystal layer interposed between the first and second transparent substrate layers, and is an active liquid crystal lens selectively having refractive power by controlling the liquid crystal layer with an electrode disposed on at least one surface of the first and second transparent substrate layers.

The light-path converter may include an active reflector that adjusts a transmission amount of external light. The active reflector may include one of a liquid crystal filter and an electrochromic device.

The light-path converter may be disposed near the pupil of the user.

The see-through type holographic display device may be mounted in a head mounted housing worn on the head of an observer for at least one of the left and right eyes.

According to another aspect of the present disclosure, there is provided a Head Mounted Display (HMD) device displaying a hologram, including a left-eye see-through type hologram display device; a right-eye see-through type holographic display device; and a frame connecting the left-eye perspective type holographic display device and the right-eye perspective type holographic display device, wherein the left-eye perspective type holographic display device and the right-eye perspective type holographic display device each include: a light source providing light; a spatial light modulator which diffracts the light and reproduces the hologram; a relay optical system that enlarges or reduces and transmits the hologram generated by the spatial light modulator; a noise removal filter that removes noise from diffracted light of the hologram transmitted via the relay optical system; and an optical path converter changing at least one of a path of diffracted light of the hologram transmitted from the relay optical system and a path of external light, and transmitting the diffracted light and the external light to the same area.

When the HMD device is worn on the head of the user, the light-path converter of the left-eye see-through type holographic display device may be disposed adjacent to the left eye of the user, and the light-path converter of the right-eye see-through type holographic display device may be disposed adjacent to the right eye of the user.

The distance between the optical path converter of the left-eye see-through type hologram display device and the optical path converter of the right-eye see-through type hologram display device can be adjusted.

Drawings

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic diagram of an example of a see-through holographic display device worn by a user according to an embodiment;

FIG. 2 is a schematic diagram of an optical system of the perspective type holographic display device of FIG. 1;

fig. 3 is a diagram of an example of the layout of the objective lens;

fig. 4 is a diagram of another example of the layout of the objective lens;

fig. 5 is a diagram describing the operation of the layout of the objective lens of fig. 4;

fig. 6 is a schematic diagram of an optical system of a perspective type holographic display device according to another embodiment;

fig. 7 is a schematic view of an optical system of a perspective type holographic display device according to another embodiment;

fig. 8 is a schematic view of an optical system of a perspective type holographic display device according to another embodiment;

fig. 9 is a schematic view of an optical system of a perspective type holographic display device according to another embodiment;

fig. 10 is a diagram describing an operation of the perspective type holographic display device of fig. 9;

fig. 11 is a schematic view of an optical system of a perspective type hologram display device according to another embodiment;

fig. 12 is a schematic view of an optical system of a perspective type hologram display device according to another embodiment;

fig. 13 is a schematic view of an optical system of a perspective type hologram display device according to another embodiment;

fig. 14 is a diagram of an example of a beam selective optical element used in the see-through type holographic display device of fig. 13;

fig. 15A to 15C are diagrams of examples of beam selective optical elements used in the see-through type hologram display device of fig. 13;

fig. 16 is a schematic plan view of an example of a Head Mounted Display (HMD) device (see-through holographic display device) worn by a user according to another embodiment; and

fig. 17 is a schematic diagram of an optical system of the device of the HMD of fig. 16.

Detailed Description

Hereinafter, a perspective type hologram display device is described in detail with reference to the accompanying drawings. Like reference numerals refer to like elements, and in the drawings, the sizes of the elements are exaggerated for clarity and convenience of explanation.

Fig. 1 is a schematic diagram of an example of a see-through type holographic display device 100 worn by a user (observer) 10 according to an embodiment. Fig. 2 is a schematic diagram of a relay optical system 140 of the perspective type holographic display device 100 of fig. 1.

Referring to fig. 1, a see-through type holographic display device 100 according to an embodiment may be a wearable device such as glasses worn on the head of a user 10. For example, the see-through type holographic display device 100 may have the shape of a monocular glasses through which one of the two eyes 11 of the user 10 (e.g., the left eye 11L shown in fig. 1) sees the hologram and the outside. As another example, the see-through type hologram display apparatus 100 may have a shape of one of eyepieces (eye lenses) attached to glasses, for example, the left eye 11L shown in fig. 1.

The see-through type holographic display device 100 may include a case 190, an optical system installed in the case 190, and a control unit 900 controlling the optical system. The control unit 900 may be disposed outside or inside the housing 190.

Referring to fig. 2, the see-through type hologram display apparatus 100 of the present embodiment may include a light source unit 110 providing light, a spatial light modulator 120 forming a hologram, a relay optical system 140 enlarging or reducing and transmitting the hologram generated by the spatial light modulator 120, and an optical path converter 180 changing at least one of a path of diffracted light of the hologram transmitted from the relay optical system 140 and a path of external light Lo and transmitting the diffracted light of the hologram and the external light Lo to the same area. The see-through type hologram display apparatus 100 may further include a noise removal filter 150 that removes noise from diffracted light of the hologram transmitted by the relay optical system 140. The see-through type holographic display device 100 may further include an objective lens 170 that collimates the hologram transmitted from the relay optical system 140. The see-through holographic display device 100 may further comprise a control unit 900 which controls the spatial light modulator 120 to generate the hologram.

The light source unit 110 may include a light source 111. The light source 111 may include a Laser Diode (LD) to provide light with high spatial coherence to the spatial light modulator 120. However, if the light provided by the light source 111 has a certain degree of spatial coherence, the light source 111 may comprise a Light Emitting Diode (LED) since the light is sufficiently diffracted and modulated by the spatial light modulator 120. The light source 111 may be configured as an array of red, green, and blue light sources, as described later, to implement a color hologram by RGB time division driving. For example, the light source 111 may include an array of multiple lasers or LEDs. The light source 111 may include any other light source other than a laser light source or an LED as long as light having spatial coherence is emitted.

The light source unit 110 may illuminate collimated parallel light. For example, a collimating lens 112 may also be provided in the light source unit 110 to collimate the light emitted from the light source 111 into parallel light.

The spatial light modulator 120 may form a hologram pattern on its modulation surface according to the hologram data provided by the control unit 900. Light incident on the spatial light modulator 120 may be changed into diffracted light, which is modulated into an image of a holographic wavefront through a hologram pattern. As described later, the diffracted light of the image having the holographic wavefront on the spatial light 120 causes the hologram to be seen in the viewing aperture (VW) by diffraction interference via the relay optical system 140 and the objective lens 170.

The spatial light modulator 120 may include an amplitude spatial light modulator that performs only amplitude modulation, thereby preventing resolution from deteriorating and suppressing quality deterioration of a 2D image when the 2D image is formed. For example, the spatial light modulator 120 may include a Digital Micromirror Device (DMD), a liquid crystal on silicon (LCoS), or a semiconductor light modulator. A complex spatial light modulator that modulates both phase and amplitude or a phase spatial light modulator that modulates phase may also be used as the spatial light modulator 120.

An optical splitter 130 that splits incident light and emitted light may be located between the light source 111 and the spatial light modulator 120. In this regard, incident light and emitted light may refer to light incident on the spatial light modulator 120 and light emitted from the spatial light modulator, respectively. The light splitter 130 may allow light incident from the light source 111 to pass through and proceed to the spatial light modulator 120, and may be a beam splitter that reflects light reflected from the spatial light modulator 120 toward the relay optical system 140. As another example, the optical splitter 130 may be a half mirror (half mirror).

The light illuminated by the light source unit 110 may be polarized. The light source 111 may emit polarized light, or the light source 110 may include a polarizing filter to polarize light emitted from the light source 111. In this case, the optical splitter 130 may be a polarization beam splitter. A polarization conversion member such as 1/4 polarization plate may also be disposed between the light splitter 130 and the spatial light modulator 120 to distinguish the polarization of light from the light splitter 130 to the spatial light modulator 120 and the polarization of light reflected from the spatial light modulator 120, thereby more effectively splitting incident light and emitted light.

The reflective member 113 may be positioned between the light source 111 and the light splitter 130. The reflecting member 113 may be a total reflection prism or a pure mirror (mere mirror). The reflective member 113 may provide for proper placement of optical components, such as the light source 111, etc., in the limited space of the housing 190.

Relay optics 140 may be a modified 4f optical system that magnifies or reduces and transmits the image of the holographic wavefront produced by spatial light modulator 120. For example, the relay optical system 140 may include a first relay lens 141 having a first focal length f1 and a second relay lens 143 having a second focal length f 2. The first relay lens 141 may be disposed such that the modulation surface of the spatial light modulator 120 is positioned at or near the position of the first focal length f1 on the incident surface side of the first relay lens 141. The second relay lens 143 may be disposed such that the second focal length f2 of the incident surface side thereof is positioned at or near the position of the first focal length f1 of the emission surface side of the first relay lens 141. According to the optical layout of the relay optical system 140, the image of the holographic wavefront generated on the modulation surface of the spatial light modulator 120 can be imaged at the second focal length f2 on the emission surface side of the second relay lens 143. The image of the holographic wavefront imaged by relay optics 140 is referred to below as the imaged SLM (172 of fig. 3).

The first focal length f1 may be different from the second focal length f 2. For example, the second focal length f2 may be greater than the first focal length f1 so that the relay optics 140 may magnify the imaged SLM 172. Alternatively, the first focal length f1 may be greater than the second focal length f2 so that the relay optics 140 can demagnify the imaged SLM 172. As described later, since the size of the imaged SLM 172 is proportional to the Viewing Angle (VA), the VA can be changed by enlarging or reducing the imaged SLM 172.

The noise removal filter 150 may be disposed at or near a position where the first focal length f1 on the emission surface side of the first relay lens 141 and the second focal length f2 on the incident surface side of the second relay lens 143 overlap each other. The noise removal filter 150 may be, for example, a pinhole. The noise removing filter 150 may be placed at the first focal length f1 of the first relay lens 141 of the relay optical system 140 and may block light other than the desired diffraction order light, thereby removing noise, such as a diffraction pattern or multiple diffraction, due to the pixel structure of the spatial light modulator 120.

As described above, the image of the holographic wavefront formed on the modulating surface of spatial light modulator 120 may form an imaged SLM 172 through relay optics 140. The objective lens 170 may focus the imaged SLM 172 in front of the pupil 13 of the user 10 to form a viewing aperture in front of the pupil 13 of the user 10. The viewing aperture may be understood as the space where the user 10 sees the hologram. The layout of the objective lens 170 is described later with reference to fig. 3.

The light-path converter 180 may be a beam splitter that reflects the diffracted light transmitted from the relay optical system 140 and allows the external light Lo to transmit therethrough. The light-path converter 180 may be configured such that the light beam incident to and transmitted through the first incident surface 180a is reflected from the beam splitting film 181 located inside the light-path converter 180 and emitted to the emission surface 180c, and the light beam incident to and transmitted through the second incident surface 180b is transmitted through the beam splitting film 181 and emitted to the emission surface 180 c.

As an example, the beam splitting film 181 may be a half mirror. In this case, the light illuminated by the light source unit 110 is not necessarily limited to polarized light.

As another example, when the light illuminated by the light source unit 110 is polarizable, the beam splitting film 181 of the light-path converter 180 may be a polarization selective reflective film. If the polarization direction of the light beam incident to the first incident surface 180a is a first polarization direction and the polarization direction orthogonal to the first polarization direction is a second polarization direction, the beam splitting film 181 may have polarization selectivity, and light having the first polarization direction (hereinafter, referred to as light of the first polarization direction) is reflected and light having the second polarization direction (hereinafter, referred to as light of the second polarization direction) is transmitted. Since the external light Lo has both the first polarization component and the second polarization component, if the beam splitting film 181 has polarization selectivity, only the second polarization component contained in the external light Lo incident from the second incident surface 180b may pass through the beam splitting film 181 to reach the pupil 13 of the user's eye 11.

The first incident surface 180a of the light-path converter 180 may be adjacent to the objective lens 170. The emitting surface 180c of the light-path converter 180 may be adjacent to the pupil 13 of the user's eye 11.

The optical path converter 180 may be an example of an optical member that changes at least one of a path of diffracted light of the hologram transmitted from the relay optical system 140 and a path of external light Lo, and transmits the diffracted light and the external light Lo to the same area (i.e., the pupil 13 of the user's eye 11).

As described above, the see-through type holographic display device 100 according to the embodiment may be a wearable device worn on the head of the user 10, and thus, the housing 190 may have a shape of a monocular glasses, which is a close-fitting part from the eyes to the ears of the user 10, or may have a shape of one of lenses attached to the glasses.

For example, the housing 190 may include a first housing portion 190A adjacent the ear, a curved portion 190B, and a second housing portion 190C adjacent the eye 11. The first housing portion 190A, the bent portion 190B, and the second housing portion 190C may be integrally formed, but are not limited thereto. The first housing portion 190A may have, for example, the light source unit 110, the spatial light modulator 120, the light splitter 130, the relay optical system 140, and the noise removing filter 150. The second housing portion 190C may have, for example, an objective lens 170 and an optical-path converter 180. The curved portion 190B may have a reflecting member 160 such as a total reflection prism or a pure reflecting mirror that curves the optical path according to the shape of the housing 190. The second relay lens 143 of the relay optical system 140 or the noise removing filter 150 may be disposed in the second housing portion 190C according to the size of the housing 190 or the focal length of the relay optical system 140 of the optical system. The second housing portion 190C may include a first window 191 disposed at a position facing the eye 11 of the user 10 and a second window 192 disposed at a position facing the first window 191 such that the second window 192 is singapore to the person when the see-through type holographic display device 100 is worn on the head of the user 10. The first and

second windows

191 and 192 may comprise glass or a transparent plastic material or may be an open portion of the second housing portion 190C. The light-path converter 180 may be disposed such that the second incident surface 180b is located near the second window 192. According to the above-described arrangement, the external light Lo may be incident to the light-path converter 180 via the second window 192, and may reach the eye 11 of the user 10 via the light-path converter 180 and the first window 191. In other words, the user 10 can see the outside via the first window 191, the light-path converter 180, and the second window 192. According to the above arrangement, the light-path converter 180 may be disposed adjacent to the eye 11 of the user 10.

The layout of the objective lens 170 is described below.

Fig. 3 is a diagram of an example of the layout of the objective lens 170. For convenience of explanation, fig. 3 shows diffracted light which is not bent by the beam splitting film 181 of the light-path converter 180 of fig. 2. Referring to FIG. 3, objective lens 170 may be disposed at or near the location of SLM 172 being imaged. If the light modulation surface of the spatial light modulator 120 is disposed at or near the position of the first focal length f1 on the incident surface side of the first relay lens 141, since the SLM 172 for imaging is formed at or near the second focal length f2 on the emission surface side of the second relay lens 143, the objective lens 170 may be disposed at or near the second focal length f2 on the emission surface side of the second relay lens 143.

Fig. 4 is a diagram of another example of the layout of the objective lens 170. For convenience of explanation, fig. 4 also shows diffracted light which is not bent by the beam splitting film 181 of the light-path converter 180 of fig. 2. Referring to fig. 4, the objective lens 170 may be arranged such that an imaging SLM 172 is placed between a front focal point (object side focal point) Fo of the objective lens 170 and an incident surface of the objective lens 170.

The operation of the see-through type holographic display device 100 will now be described with reference to fig. 2. The control unit 900 may generate hologram data and provide a hologram data signal to the spatial light modulator 120. The holographic data signal may be a Computer Generated Hologram (CGH) signal that is computed to reconstruct a target hologram in space. The color hologram may be implemented by RGB time division driving. For example, the control unit 900 may sequentially drive the red, green, and blue light sources of the light source unit 110, transmit hologram data signals corresponding to the red, green, and blue holograms, and sequentially display the red, green, and blue holograms, whereby a color hologram may be displayed.

The spatial light modulator 120 may form a hologram pattern on a surface of the spatial light modulator 120 according to the hologram data signal provided by the control unit 900. The principle of the spatial light modulator 120 forming the holographic pattern may be the same as that of, for example, a display panel displaying an image. For example, a holographic pattern may be displayed on the spatial light modulator 120 as an interference pattern that includes information related to the hologram to be reproduced. Then, the light can be changed into diffracted light by the hologram pattern formed by the spatial light modulator 120, and the diffracted light is modulated to have a holographic wavefront on the modulation surface of the spatial light modulator 120.

The diffracted light produced by spatial light modulator 120 may pass through relay optics 140 to form an imaged SLM 172.

The spatial light modulator 120 may be configured as an array of a plurality of pixels, whereby the array of the plurality of pixels serves as a pixel lattice. Thus, the incident light may be diffracted and interfered not only by the hologram pattern formed by the spatial light modulator 120 but also by the pixel lattice configured as a bright red array of the spatial light modulator 120. A part of the incident light is not diffracted by the holographic pattern of the spatial light modulator 120 but may be transmitted through the spatial light modulator 120. As a result, a plurality of grid points may appear on the pupil plane on which the hologram is focused as a spot, VW being placed. The plurality of lattice points may act as image noise, which deteriorates the plurality of holograms and makes it inconvenient to enjoy the holograms. The noise removing filter 150 may be placed at the first focal length f1 of the first relay lens 141 of the relay optical system 140, and may block light other than the desired diffraction order light, thereby removing noise, such as a diffraction pattern or multiple diffraction, due to the spatial light modulator 120.

The objective lens 170 may collimate the imaged SLM 172 to form VW in front of the pupil 13 of the eye 11 of the user 10. That is, the holographic wavefront formed by the relay optical system 140 (i.e. the imaged SLM 172) can diffract and interfere in the VW, whereby the objective lens 170 causes the 3D hologram to be seen.

Meanwhile, as described above, the beam splitting film 181 of the optical-path converter 180 of fig. 2 may allow the external light Lo of fig. 2 to pass therethrough, whereby not only the hologram but also a scene outside the second window 192 of fig. 2 can be seen in the VW.

As shown in FIG. 3, when the objective lens 170 is disposed at or near the location of the imaging SLM 172, the image seen by the user via the objective lens 170 can be the imaging SLM 172. That is, when reconstructing the hologram, the user 10 can enjoy the hologram in a viewing position (VW) at a distance d from the imaged SLM 172. In this regard, the VA or field of view (FOV) of the reconstructed hologram may be controlled according to the size S of the imaged SLM 172 and the distance d of the imaged SLM 172 from the VW. That is, if the size S of the imaged SLM 172 increases, the VA of the FOV may increase, and if the size S of the imaged SLM 172 decreases, the VA of the FOV may decrease. The size S of the imaged SLM 172 may be determined according to the size of the spatial light modulator 120 and the magnification of the relay optical system 140. Meanwhile, if the distance d of the imaged SLM 172 from the VW decreases, the VA or FOV may increase. The distance d of the SLM 172 to be imaged from the VW can be determined from the F value F/# of the objective lens 170. As described above, the objective lens 170 and the light-path converter 180 are disposed in contact with the pupil 13 of the user 10, whereby the distance d of the SLM 172 to be imaged to the VW can be decreased, and accordingly, the VA or FOV can be increased.

As shown in fig. 4, the imaging SLM 172 may be placed between the front focal point (object side focal point) Fo of the objective lens 170 and the incident surface of the objective lens 170. Fig. 5 is a diagram describing the operation of the layout of the objective lens 170 of fig. 4. When the imaging SLM 172 is placed between the front focal point (object side focal point) Fo of the objective lens 170 and the incident surface of the objective lens 170, as shown in fig. 5, the image seen through the objective lens 170 may be an upright virtual imaging SLM 173 through the objective lens 170. In this regard, the dimension S' of the upright virtual imaging SLM 173 can satisfy the following equation for the lens with respect to the dimension S of the imaging SLM 172,

[ equation 1]

Where negative sign-denotes a virtual image, a denotes the distance between the imaged SLM 172 and the objective lens 170, b denotes the distance between the upright virtual imaged SLM 173 and the objective lens 170, and f3 denotes the front focal length of the objective lens 170.

The user 10 can enjoy the hologram in a viewing position (VW) at a distance d' from the SLM 173, which is virtually imaged upright. In this regard, the VA or FOV of the reconstructed hologram may be controlled depending on the size S 'of the upright virtual imaged SLM 173 and the distance d' of the upright virtual imaged SLM 173 from the VW. That is, if the size S 'of the upright virtual imaged SLM 173 increases, VA or FOV increases, and if the size S' of the upright virtual imaged SLM 173 decreases, VA or FOV decreases. The size S' of the upright virtual imaging SLM 173 can be determined based on the positional relationship between the imaging SLM 172 and the objective lens 170, as shown in equation 1 above. In more detail, when the front focus Fo of the objective lens 170 is disposed closer to the imaging SLM 172, the size S' of the upright virtual imaging SLM 173 is greatly increased, and thus VA or FOV can be greatly increased.

An immersive holographic display device implementing a hologram by using a composite spatial light modulator is known as a holographic display device applied to a conventional HMD, however, the composite spatial light modulator may require a complex structure, cause deterioration in resolution, and cause deterioration in 2D image quality when expressing a 2D image. It is necessary for ultra-high definition complex spatial light modulators to minimize the effects of higher order diffraction, and the FOV may be limited by the size of the complex spatial light modulator. Thus, a complex spatial light modulator with ultra-high definition pixels can have a relatively narrow FOV with respect to the same resolution.

Meanwhile, the see-through type hologram display apparatus 100 of the present embodiment may determine the size S of the imaged SLM 172 or the size S' of the upright virtual imaged SLM 173 not only according to the size of the spatial light modulator 120 but also according to the configuration of the optical system (e.g., the magnification of the relay optical system 140, the F value F/# of the objective lens 170, or the position of the objective lens 170, etc.), whereby the VA or FOV of the hologram is not limited by the size of the spatial light modulator 120.

An example of RGB time-division driving for implementing a color hologram is described in the present embodiment, but the embodiment is not limited thereto. As another example, the light source unit 110 may illuminate white light and use a liquid crystal panel including a color filter as the spatial light modulator 120, thereby implementing a color hologram according to spatial division.

The case where the light source unit 110 illuminates collimated parallel light is described in the above embodiment. However, the light source unit 110 may illuminate divergent light or convergent light. In this case, the light source unit 110 may include a lens that diverges or converges light instead of a collimating lens. The objective lens 170 may be omitted according to circumstances.

Although the see-through type hologram display device 100 is worn on the left eye 11L of the user 10 in fig. 1 and 2, the see-through type hologram display device 100 may be worn on the right eye 11R of the user 10. The see-through type hologram display device 100 worn on the right eye 11R may have a symmetrical structure with the see-through type hologram display device 100 worn on the left eye 11L.

Fig. 6 is a schematic diagram of an optical system of a perspective type holographic display device 200 according to another embodiment. Referring to fig. 6, a see-through type hologram display apparatus 200 of the present embodiment is substantially the same as the see-through type hologram display apparatus 100 described with reference to fig. 1 to 5, except that the see-through type hologram display apparatus 200 uses a transmissive spatial light modulator 220. The transmissive spatial light modulator 220 may include, for example, a light modulator using a Liquid Crystal Device (LCD) or a semiconductor light modulator based on a compound semiconductor such as GaAs. Light emitted from the light source unit 110 is diffracted and modulated by the transmissive spatial light modulator 220. The diffracted light passing through the transmissive spatial light modulator 220 may be focused in front of the pupil 13 of the eye 11 of the user 10 via the relay optical system 140, the objective lens 170, and the light-path converter 180 to form VW.

Fig. 7 is a schematic diagram of an optical system of a perspective type holographic display device 300 according to another embodiment. Referring to fig. 7, a see-through type hologram display apparatus 300 of the present embodiment is substantially the same as the see-through type hologram display apparatus 100 described with reference to fig. 1 to 5, except that the see-through type hologram display apparatus 300 uses an active reflector 380 as an optical path converter. The active reflector 380 may be an optical component that actively adjusts reflection and transmission under the control of the control unit 901. For example, as a transmission adjustment device using Liquid Crystal (LC), the active reflector 380 may include an electrochromic device or the like, along with a (semi-transparent) mirror. A reflective coating or a film with other additional functions that can increase the amount of light toward the pupil 13 of the user 10 may be additionally disposed on the beam splitting film of the active reflector 380. The active reflector 380 may function as an optical path converter, whereby the control unit 901 may adjust the amount of light incident from the outside to the pupil 13 in a case where it is difficult to observe the hologram due to an extremely bright external environment.

Fig. 8 is a schematic diagram of an optical system of a perspective type holographic display device 400 according to another embodiment. Referring to fig. 8, the perspective type holographic display device 400 of the present embodiment may include a light-path converter 480 (such as the beam splitter described with reference to fig. 1 to 5) and a separation transmissive adjusting means 485 disposed on a second incident surface 480b of the light-path converter 480. Since transmissive adjustment device 485 can be used separately, control section 902 can adjust the amount of external light Lo incident from the outside to pupil 13 via second window 192 when the hologram is not easily observed due to an extremely bright external environment.

Fig. 9 is a schematic diagram of an optical system of a see-through holographic display device 500 according to another embodiment. Fig. 10 is a diagram describing an operation of the see-through type holographic display device 500 of fig. 9.

Referring to fig. 9, the see-through type hologram display apparatus 500 of the present embodiment is substantially the same as the see-through type hologram display apparatus 100 described with reference to fig. 1 to 5, except that the see-through type hologram display apparatus 500 further includes a moving lens holder 546 which can move the second relay lens 543 of the relay optical system 540 in the optical axis direction 546 a. The moving lens holder 546 may include a motor (not shown) to move the second relay lens 543 in the optical axis direction 546a under the control of the control unit 903. As another example, the moving lens holder 546 may manually move the second relay lens 543 in the optical axis direction 546 a. If the second relay lens 543 is moved in the optical axis direction 546a, the size of the imaged SLM 172 formed by the relay optical system 540 may be adjusted, or the position of the imaged SLM 172 may be moved, as shown in fig. 10.

In more detail, the diffracted light formed by the spatial light modulator 120 via the first relay lens 541 of the relay optical system 540 may diverge after being focused at the focal position on the emission surface side of the first relay lens 541. Similar to the perspective type hologram display device 100 described with reference to fig. 1 to 5, if the second relay lens 543 is located at a point (hereinafter referred to as an original position) where the focal position of the incident surface side of the second relay lens 543 is the same as the focal position of the emission surface side of the first relay lens 541, the size of the SLM 172 to be imaged may be S1. However, if the second relay lens 543 is moved closer to the first relay lens 541 in the direction 547 from the original position, the size of the imaged SLM 172 may be reduced to S2. As a result, the user can see the small-sized (S2) imaged SLM 172, whereby the VA or FOV can be reduced. In contrast, if the second relay lens 543 is moved from the original position in a direction away from the first relay lens 541, since the size of the imaged SLM 172 is larger than S1, the user can see the large-sized imaged SLM 172, and thus VA or FOV can be increased. As described above, the see-through type hologram display apparatus 500 of the present embodiment can adjust the FOV by moving the lens position of the relay optical system 540, as described with reference to fig. 3.

As described above, if the second relay lens 543 is moved in the optical axis direction 546a, since the position of the imaged SLM 172 is also moved, as described with reference to fig. 4, the position of the imaged SLM 172 can be adjusted between the front focal point Fo of the objective lens 170 and the incident surface of the objective lens 170, and thus the size (S' of equation 1) of the upright virtual imaged SLM 172 can be adjusted, thereby adjusting the FOV.

Meanwhile, if the FOV is increased, the image quality may be deteriorated since a Pixel Per Inch (PPI) of the hologram is decreased, and if the FOV is decreased, the image quality is improved since the PPI of the hologram is increased.

Fig. 11 is a schematic diagram of an optical system of a perspective type holographic display device 600 according to another embodiment. Referring to fig. 11, a see-through type hologram display apparatus 600 of the present embodiment is substantially the same as the see-through type hologram display apparatus 100 described with reference to fig. 1 to 5, except that the see-through type hologram display apparatus 600 uses a field mirror 670 instead of the objective lens 170 described with reference to fig. 1 to 5. The light-path converter 680 may be a beam splitter. The beam splitting film 681 of the light-path converter 680 may be disposed such that diffracted light incident on and transmitted through the first incident surface 680a and external light Lo incident on and transmitted through the second incident surface 680b may be transmitted toward the emitting surface 680c, and light incident on and transmitted through the third surface 680d may be reflected toward the emitting surface 680c, as shown in fig. 11. In this regard, the third surface 680d may be opposite to the first incident surface 680 a. The field mirror 670 may be disposed adjacent to the third surface 680d of the light-path converter 680.

According to the above-described layout, diffracted light via the relay optical system 140 may be incident on the first incident surface 680a of the light-path converter 680 and may be emitted to the third surface 680d via the beam splitting film 681. The diffracted light emitted from the third surface 680d may be reflected from the field mirror 670, may be incident again to the third surface 680d of the light-path converter 680, may be reflected from the beam splitting film 681, and may then be emitted through the emitting surface 680c, whereby the diffracted light may reach the pupil 13 of the eye 11 of the user 10. In this regard, the diffracted light may be collimated into parallel light incident to the field mirror 670 and may be focused by the field mirror 670 to form VW at the pupil 13. Meanwhile, the external light Lo may be incident on the second incident surface 680d of the light-path converter 680 and then may be emitted to the emitting surface 680c via the beam splitting film 681, whereby the external light Lo may reach the pupil 13 of the user 10.

Fig. 12 is a schematic diagram of an optical system of a perspective type holographic display device 700 according to another embodiment. Referring to fig. 12, a see-through type hologram display device 700 of the present embodiment is substantially the same as the see-through type hologram display device 100 described with reference to fig. 1 to 5, except that the see-through type hologram display device 700 uses a light-path converter 780 having a curved surface beam splitting film 781 instead of the objective lens 170 and the light-path converter 180 described with reference to fig. 1 to 5.

The light-path converter 780 may be a beam splitter including a beam splitting film 781 formed in a concave curved surface with respect to the first incident surface 780 a. The light-path converter 780 may have a shape in which two portions separated by the beam splitting film 781 are combined with respect to the beam splitting film 781 through a boundary. In this regard, the two portions of the light-path converter 781 have substantially the same refractive index.

The beam splitting film 781 of the light-path converter 780 may be a semi-transparent mirror. In this case, the light illuminated by the light source unit 110 is not necessarily limited to polarized light.

As another example, when the light illuminated by the light source unit 110 is polarizable, the beam splitting film 781 of the light-path converter 780 may be a polarization selective film. For example, the beam splitting film 781 may have polarization selectivity such that light incident to the first polarizing surface 780a (i.e., polarized light emitted from the light source 110) is reflected and light of the second polarization is transmitted. Since the external light Lo has both the first polarization component and the second polarization component orthogonal to the first polarization direction, if the beam separating film 781 has polarization selectivity, only the second polarization component contained in the external light Lo incident from the second incident surface 780b may pass through the beam separating film 781 and reach the pupil 13 of the user's eye 11.

The curved surface of beam splitting film 781 may be designed such that light beams incident to first polarizing surface 780a are reflected and focused in beam splitting film 781 to form VW in front of pupil 13 of user's eye 11. The focusing of the light beam by the beam splitting film 781 may replace the function of the objective lens 170 described with reference to fig. 1 to 10 or the function of the field mirror 670 described with reference to fig. 11. Thereby, the optical path changer 780 may be disposed at a position corresponding to the position of the objective lens 170 described above. For example, the light-path converter 780 may be disposed such that the beam splitting film 781 is placed near the image plane (172 of fig. 3) on which the hologram transmitted from the relay optical system 140 is imaged.

Meanwhile, since the two portions of the light-path converter 780 combined by a boundary with respect to the beam splitting film 781 have substantially the same refractive index, no refraction occurs when the external light Lo passes through the beam splitting film 781. In other words, external light Lo passes through beam splitting film 781 without refraction, and a user can see an external scene without distortion.

Fig. 13 is a schematic diagram of an optical system of a perspective type holographic display device 800 according to another embodiment.

Referring to fig. 13, an optical system of a see-through type hologram display device 800 of the present embodiment is substantially the same as the optical system of the see-through type hologram display device 700 described with reference to fig. 7, except that the optical system of the see-through type hologram display device 800 further includes a beam selective optical element 890, and thus, differences are mainly described below.

The light source unit 110 may illuminate polarized light. As described with reference to fig. 2, when the light source unit 110 illuminates polarized light, the light splitter 130 may be a polarization beam splitter, and a polarization conversion member such as an 1/4 polarization plate (not shown) may also be disposed between the light splitter 130 and the spatial light modulator 120. The light path converter 880 may have polarization selectivity and include a beam separating film 881 formed with a predetermined curved surface. As described with reference to fig. 12, the beam separating film 881 may have polarization selectivity, in which light of the first polarization (i.e., light of the polarization emitted from the light source 110) incident to the first polarizing surface 880a is reflected and light of the second polarization is transmitted. Since the external light Lo has a first polarization component and a second polarization component orthogonal to the first polarization direction, only the second polarization component contained in the external light Lo may pass through the beam splitting film 881 and reach the pupil 13 of the user's eye 11. As described below, the beam selective optical element 890 has a positive (+) refractive power only with respect to the first polarized light and has no refractive power with respect to the second polarized light. Thus, the curved surface of the beam separating film 881 may be designed in consideration of the refractive power of the beam selective optical element 890.

Fig. 14 is a diagram of an example of a beam selective optical element 890 used in the perspective type holographic display device 800 of fig. 13. The beam selective optical element 890 of fig. 14 is a polarization dependent lens having different refractive indices with respect to the first polarized light and the second polarized light. Referring to fig. 14, the beam selective optical element 890 may be a cemented lens, with the first lens 891 and the second lens 892 cemented together. The first lens 891 may be an isotropic lens comprising, for example, glass or an isotropic polymeric material. The second lens 892 may be an anisotropic lens comprising an anisotropic polymeric material having different refractive indices according to polarization direction. The second lens 892 comprising an anisotropic polymeric material may have a different refractive index than the first lens 891 with respect to light of the first polarization and may have the same refractive index as the first lens 891 with respect to light of the second polarization. The incident surface 890a of the beam selective optical element 890 (i.e., the incident surface of the first lens 891) and the emitting surface 890c of the beam selective optical element 890 (i.e., the emitting surface of the second lens 892) may be flat surfaces. The boundary surface 890b between the first lens 891 and the second lens 892 may be a curved surface having a predetermined curvature. The curved surface of the boundary surface 890b may be designed such that a beam of the first polarization incident on the incident surface 890a of the beam selective optical element 890 is focused to form VW in front of the pupil 13 of the user's eye 11.

The operation of the see-through type hologram display device 800 of the present embodiment will now be briefly described.

The light having the polarization illuminated by the light source unit 110 may have predetermined hologram information and may be diffracted via the spatial light modulator 120 and incident as diffracted light of the first polarization to the first polarization surface 880a of the optical path changer 880 via the relay optical system 140 and the noise removing filter 150. The light path converter 880 may be configured such that the first polarized light may be reflected in the beam splitting film 881, focused by the curvature of the beam splitting film 881, and emitted through the emission surface 880 c. The first polarized light emitted from the light-path converter 880 may be focused in the beam selective optical element 890 to form VW in front of the pupil 13 of the user's eye 11, whereby the user may see the hologram.

The external light Lo may be incident to the second polarization surface 880b of the light path converter 880. Only light of the second polarization perpendicular to the first polarization, which is included in the external light Lo, may pass through the beam splitting film 881 of the light path converter 880 and be emitted through the emitting surface 880 c. The external light Lo of the second polarization emitted from the light path converter 880 may pass through the beam selective optical element 890 without refraction, whereby a user may see an undistorted external scene.

In the present embodiment, the light-path converter 880 and the beam-selective optical element 890 may be designed with respect to the first polarized light by distributing the refractive power, whereby the optical design is further free in terms of the degree of freedom, and VA may be sufficiently increased. According to circumstances, when the beam selective optical element 890 sufficiently controls the refractive power, the beam separating film 881 of the light path converter 880 may be formed into a flat surface.

Fig. 15A to 15C are diagrams of examples of beam selective

optical elements

990, 990', and 990 ″ used in the perspective type holographic display device 800 of fig. 13.

Referring to fig. 15A, the beam selective optical element 990 may include first and second

transparent substrate layers

991 and 992 opposite to each other and a liquid crystal layer 994 interposed between the first and second

transparent substrate layers

991 and 992. At least one surface between the opposite surfaces of the first and second

transparent substrate layers

991 and 992 may be formed with a curved surface so that the beam selective optical element 990 may have a predetermined refractive power according to the orientation of the liquid crystal layer 994. First and

second electrodes

996 and 997 may be disposed in the first and second transparent base layers 991 and 992, respectively. The power supply 998 may apply a voltage to the first and

second electrodes

996 and 997. The liquid crystals of the liquid crystal layer 994 may be aligned by an applied voltage. Reference numeral 995 denotes a barrier sealing the liquid crystal layer 994. The refractive index and polarization characteristics of the liquid crystal layer 994 may be changed according to the alignment of the liquid crystal, and thus the beam selective optical element 990 of the present embodiment may be an active lens. As an example, when no voltage is applied to the liquid crystal layer 994, the first polarized light or the second polarized light may actually be transmitted through the liquid crystal layer 994, whereby a user may see both the hologram and the external scene. When a voltage is applied to the liquid crystal layer 994, only the first polarized light may be focused after being transmitted through the liquid crystal layer 994, and thus, a user sees only the hologram. As another example, in a case where a voltage is applied to the liquid crystal layer 994 and only the second polarized light is transmitted through the liquid crystal layer 994, when a voltage is not applied to the liquid crystal layer 994, both the first polarized light and the second polarized light may be actually transmitted through the liquid crystal layer 994, and thus a user may see both a hologram and an external scene, and when a voltage is applied to the liquid crystal layer 994, only the second polarized light may be focused after being transmitted through the liquid crystal layer 994, and thus a user may see only an external scene.

Although the inner surface of the second lens base layer 992 (i.e., the surface on which the second electrode 997 is located) is formed as a curved surface in fig. 15A, the first transparent base layer 991 may be formed as a curved surface. The first and

second electrodes

996 and 997 are disposed on opposite surfaces of the first and second transparent base layers 991 and 992, respectively, in fig. 15A, but the present disclosure is not limited thereto.

Fig. 15B illustrates a modification of the beam selective optical element 990 of fig. 15A. Referring to fig. 15B, the beam selective optical element 990 'may include first and second transparent substrate layers 991' and 992 'opposite to each other and a liquid crystal layer 994' interposed between the first and second transparent substrate layers 991 'and 992'. First and second electrodes 996 'and 997' may be disposed in the first and second transparent base layers 991 'and 992', respectively. The power supply 998 ' may apply a voltage to the first and second electrodes 996 ' and 997 '. The liquid crystals of the liquid crystal layer 994' may be aligned by an applied voltage. The polarization characteristics of the liquid crystal layer 994' may be changed according to the application of voltage. The liquid crystal layer 994 'may be sealed by a barrier 995'.

At least one of the first and second transparent substrate layers 991 'and 992' may be a bonded lens. As an example, as shown in fig. 15B, the second transparent base layer 992 ' may be formed by bonding a first lens layer 992a ' and a second lens layer 992B ' having different refractive indexes. In this regard, the second transparent base layer 992' has a flat plate shape as a whole. An adhesive surface between the first and second lens layers 992a ' and 992b ' may be convexly formed with respect to an incident surface, so that the second transparent base layer 992 ' may have a positive (+) refractive power. The shape of the adhesive surface may vary according to the refractive indexes of the first and second transmissive layers 992a 'and 992 b'. Similar to the beam selective optical element 890 described above with reference to fig. 14, the first lens layer 992a ' may include an isotropic material and the second lens layer 992b ' may include an anisotropic material, such that the second transparent substrate layer 992 ' may have different refractive indices with respect to the first polarized light (i.e., diffracted light) and the second polarized light (i.e., external light).

The beam selective optical element 990 ' of the present embodiment is different from the beam selective optical element 990 described with reference to fig. 15A in that the second transparent substrate layer 992 ' controls refractive power, and the beam selective optical element 990 ' selects only polarization.

Fig. 15C illustrates a modification of the beam selective optical element 990 of fig. 15A. Referring to fig. 15C, the beam selective optical element 990 "may include first and second transparent substrate layers 991" and 992 "opposite to each other and a liquid crystal layer 994" interposed between the first and second transparent substrate layers 991 "and 992". First and second electrodes 996 "and 997" may be disposed in the first and second transparent base layers 991 "and 992", respectively. The second electrode 997 "may be disposed on the entire surface of the second transparent substrate layer 992", and the first electrode 996 "may be disposed on a portion of the first transparent substrate layer 991" (e.g., the circumference or both sides of the first transparent substrate layer 991 "as shown in fig. 15C). The power supply 998 "may apply a voltage to the first and second electrodes 996" and 997 ". The liquid crystals of the liquid crystal layer 994 "may be aligned by an applied voltage. The liquid crystal layer 994 "may be sealed by a barrier 995".

Since the position of the first electrode 996 "is different from that of the second electrode 997", an electric field applied to the liquid crystal layer 994 "may be non-uniform. For example, when the first electrode 996 "is disposed on the circumference or both sides of the first transparent base layer 991", the electric field of the edge side of the first electrode 996 "may have a fringing field shape. Thus, if the shape of the first electrode 996 ″ and the voltage applied thereto are properly selected, the liquid crystal layer 994 ″ may have a positive (+) refractive power by a non-uniform electric field applied to the liquid crystal layer 994 ″. That is, when no voltage is applied to the liquid crystal layer 994 ″, either the first polarized light or the second polarized light may actually be transmitted through the liquid crystal layer 994 ″, whereby the user may see the hologram and the external scene. When a voltage is applied to the liquid crystal layer, only the first polarized light is focused after transmitting through the liquid crystal layer 994 ″, and thus, the user sees only the hologram.

Fig. 16 is a schematic plan view of a Head Mounted Display (HMD) device 700 (see-through holographic display device) worn by a user according to another embodiment. Fig. 17 is a schematic diagram of an optical system of the HMD apparatus 700 of fig. 10.

Referring to fig. 16, the HMD device of the present embodiment may be a device worn on the head of the user 10 (such as glasses or goggles) or attached to the glasses or goggles.

The HMD apparatus 1000 may include a left-eye see-through type display apparatus 1001, a right-eye see-through type display apparatus 1002, and a frame 803 connecting the left-eye see-through type display apparatus 1001 and the right-eye see-through type display apparatus 1002. Each of the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 may be one of the see-through type hologram display devices 100 to 600 described with reference to fig. 1 to 15. When the HMD apparatus 1000 is worn on the head of the user 10, the light-path converter 1081 of the left-eye see-through type display apparatus 1001 may be disposed adjacent to the left eye 11L of the user 10, and the light-path converter 1082 of the right-eye see-through type display apparatus 1002 may be disposed adjacent to the right eye 11R of the user 10. The left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 may display a left-eye hologram and a right-eye hologram, respectively. Since the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 are see-through type display devices, the HMD device 1000 of the present embodiment may be a see-through type display device that sees left and right eye holograms and external scenes.

A control unit 1004 that controls the optical system of the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 may be provided inside or outside the housing of one of the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002.

The location of the pupils of different users may be slightly different. Thus, the constituent elements of the position of the observation hole VW formed by each of the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 need to be adjusted so that the VW is at the pupil of the user. In this regard, the frame 1003 may move at least one of the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002 in the left-right direction 1004 to reduce or increase a space between the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002, thereby fixing the left-eye see-through type display device 1001 and the right-eye see-through type display device 1002. Such a fixing device of the frame 1003 may use a well-known method. The HMD apparatus 1000 of the present embodiment detachably includes an optical system of the left-eye see-through type display apparatus 1001 and an optical system of the right-eye see-through type display apparatus 1002, thereby easily adjusting the distance between the left-eye see-through type display apparatus 1001 and the right-eye see-through type display apparatus 1002.

The perspective type holographic display device according to the embodiment can see both the hologram and the outside at the same time.

The see-through type holographic display device according to the embodiment may adjust the size of the field of view.

The see-through type hologram display device according to the embodiment may be applied to a personal see-through type display head mounted display.

A see-through holographic display device according to embodiments may implement an optical system that implements holograms to a head-mounted display via amplitude modulation.

When the see-through type hologram display apparatus according to the embodiment is applied to a binocular head mounted display, since the left and right optical systems are completely separated, one or both of the left and right optical systems move according to a distance between the left and right pupils of a user (observer), thereby adjusting the distance between the left and right pupils.

To facilitate understanding of the see-through holographic display device, various embodiments are described and shown in the drawings. It is to be understood, however, that the embodiments described herein are to be considered in all respects only as illustrative and not restrictive. Descriptions of features or aspects within each embodiment should generally be considered as other similar features or aspects that may be used in other embodiments.

Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope defined by the following claims.

Claims

1. A see-through holographic display device, comprising:

a light source providing light;

a spatial light modulator which diffracts the light and reproduces the hologram;

a relay optical system that enlarges or reduces and transmits the hologram generated by the spatial light modulator;

a noise removal filter that removes noise from diffracted light of the hologram transmitted via the relay optical system;

an optical path converter changing at least one of a path of diffracted light of the hologram transmitted from the relay optical system and a path of external light, and transmitting the diffracted light and the external light to the same area;

a beam selective optical element that focuses the diffracted light from the optical path converter and has a positive value with respect to a refractive power of the diffracted light, and transmits the external light from the optical path converter therethrough and has zero refractive power with respect to the external light.

2. The see-through holographic display of claim 1, further comprising a collimator that converts light provided by the light source into collimated light.

3. The see-through holographic display of claim 1, wherein said spatial light modulator comprises an amplitude spatial light modulator, a phase spatial light modulator, or a complex spatial light modulator.

4. The see-through type hologram display device according to claim 1, wherein the relay optical system includes a first optical element to which the hologram modulated by the spatial light modulator is incident, and a second optical element having a second focus on the incident surface side near the first focus on the emission surface side of the first optical element.

5. The see-through holographic display of claim 4, wherein said first optical element has a first focal length and said second optical element has a second focal length different from said first focal length.

6. The see-through holographic display of claim 4, wherein said noise removal filter is disposed near the first focal point on the emission surface side of the first optical element.

7. The see-through holographic display of claim 1, wherein said noise-removal filter comprises a pinhole.

8. The see-through holographic display device of claim 1, further comprising a field optical element that focuses the hologram transmitted from the relay optical system.

9. The see-through holographic display device of claim 8, wherein said field optical element is disposed near an image plane on which a hologram transmitted from the relay optical system is imaged.

10. The see-through type holographic display device of claim 8, wherein said field optical element arrangement imaging plane is disposed between a focal position on an incident surface side of the field optical element and the incident surface of the field optical element, the hologram transferred from the relay optical system being imaged on the image plane.

11. The see-through holographic display of claim 10, wherein said field optical element arranges the image plane to be re-imaged as an erect virtual image onto the image plane of the hologram image transmitted from the relay optical system.

12. The see-through holographic display of claim 8, wherein said field optical element is disposed adjacent to an optical path converter.

13. The see-through holographic display device of claim 8, wherein a size of the hologram transmitted from the relay optical system is adjusted by changing a distance between the relay optical system and the field optical element.

14. The see-through holographic display device of claim 8,

wherein the optical path converter includes a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the third surface and transmitting at least a portion of the external light transmitted through the second surface to the third surface, and

wherein the field optical element comprises an objective lens disposed adjacent to the first surface of the optical-path converter.

15. The see-through holographic display device of claim 8,

wherein the optical path converter includes a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, a fourth surface opposite to the first surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the fourth surface, reflecting again at least a portion of the diffracted light of the hologram transmitted through the fourth surface to the third surface, and transmitting at least a portion of the external light transmitted through the second surface to the third surface, and,

wherein the field optical element comprises a concave mirror disposed adjacent to the fourth surface of the light-path converter.

16. The see-through holographic display of claim 8, wherein said light path converter comprises a semi-transparent mirror, said field optical element being located between the relay optical system and the light path converter and adjacent to the light path converter.

17. The see-through holographic display device of claim 1,

wherein the light path converter may include a beam splitter including a first surface to which diffracted light of the hologram transmitted from the relay optical system is incident, a second surface to which external light is incident, a third surface opposite to the second surface, and a beam separating film disposed inside, the beam separating film reflecting at least a portion of the diffracted light of the hologram transmitted through the first surface to the third surface and transmitting at least a portion of the external light transmitted through the second surface to the third surface, and,

wherein the beam splitting film has a concave curved surface shape with respect to the first surface to reflect and focus the hologram transmitted from the relay optical system to the third surface.

18. The see-through type holographic display device of claim 17, wherein said light path converter is arranged such that the beam splitting film is disposed near an image plane on which the hologram transmitted from the relay optical system is imaged.

19. The see-through holographic display of claim 17, wherein said beam splitting film is a polarization selective reflective film.

20. The see-through holographic display of claim 1, wherein said beam selective optical element is a cemented lens having an isotropic lens and an anisotropic lens.

21. The see-through type holographic display of claim 1, wherein the beam selective optical element comprises first and second transparent substrate layers opposite to each other and a liquid crystal layer interposed between the first and second transparent substrate layers, and selectively has a polarization characteristic by controlling the liquid crystal layer with an electrode disposed on at least one surface of the first and second transparent substrate layers.

22. The see-through type holographic display of claim 1, wherein the beam selective optical element comprises first and second transparent substrate layers opposite to each other and a liquid crystal layer interposed between the first and second transparent substrate layers, and is an active liquid crystal lens selectively having a refractive power by controlling the liquid crystal layer with an electrode disposed on at least one surface of the first and second transparent substrate layers.

23. The see-through holographic display device of claim 1, wherein said light path converter comprises an active reflector that adjusts a transmission amount of external light.

24. The see-through holographic display of claim 23, wherein said active reflector comprises one of a liquid crystal filter and an electrochromic device.

25. The see-through holographic display of claim 1, wherein said light-path converter is disposed near a user's pupil.

26. The see-through holographic display of claim 1, in which said see-through holographic display fits in a head mounted housing worn on a viewer's head for at least one of left and right eyes.

27. A head-mounted display device displaying a hologram, the head-mounted display device comprising:

a left-eye see-through holographic display device;

a right-eye see-through type holographic display device; and

a frame connecting the left-eye see-through type holographic display device and the right-eye see-through type holographic display device,

wherein, left eye perspective type holographic display device and right eye perspective type holographic display device all include:

a light source providing light;

an optical path converter changing at least one of a path of diffracted light of the hologram transmitted from the relay optical system and a path of external light, and transmitting the diffracted light and the external light to the same area; and

28. The head mounted display device of claim 27, wherein the optical path converter of the left eye see-through holographic display device is disposed adjacent to a left eye of the user and the optical path converter of the right eye see-through holographic display device is disposed adjacent to a right eye of the user when the head mounted display device is worn on the head of the user.

29. The head-mounted display device of claim 27, wherein a distance between the optical path converter of the left-eye see-through type holographic display device and the optical path converter of the right-eye see-through type holographic display device is adjustable.