KR20200063645A - Holographic head mounted display apparatus with eyebox and depth of field control and display method thereof - Google Patents

Abstract

Provided are a holographic head mounted display device capable of adjusting the image depth and an eye position, and a display method using the same. According to one embodiment, the holographic head mounted display device comprises: a spatial light modulator (SLM) in which a plane wave from a laser source is modulated by a computer generated hologram (CGH); a 4f optical unit modulated by the SLM and then forming an intermediate holographic image; and a reflective holographic optical element (HOE) diffracting light from the intermediate holographic image and providing a magnified virtual holographic image at a greater distance than an eye of a user.

Description

Holographic head mounted display device with adjustable image depth and eye position and display method using the same{HOLOGRAPHIC HEAD MOUNTED DISPLAY APPARATUS WITH EYEBOX AND DEPTH OF FIELD CONTROL AND DISPLAY METHOD THEREOF}

The following embodiments relate to a holographic head mounted display technology, and more particularly, to a holographic head mounted display device capable of adjusting image depth and eye position and a display method using the same.

Optical see-through Near-Eye-Display (NED) is a key device for Augmented Reality (AR) applications and has recently attracted attention. One of the problems of the existing proximity-eye-display (NED) is the Convergence-Accommodation Conflict (VAC). The perceived distance or vergence distance varies depending on the binocular disparity of the content, the focal length or the accommodation distance of the individual eyes, but is fixed to the physical image plane of the display panel. Due to this inconsistency, it is difficult to achieve realistic optical matching of the virtual image with the real environment in AR applications, and is known as a cause of many side effects such as eye fatigue and reduced perceived resolution.

Maxwellian proximity-eye-display (NED) is one possible approach to alleviating the convergence-control mismatch (VAC) problem. In a Maxwellian configuration, light from the display panel is concentrated at a point in the pupil plane and projected onto the eye retina. Since the effective pupil for the image is reduced to one point, the depth of field is enlarged so that the image is always focused regardless of the actual focal length of the eye lens. The removal of the depth of focus cue partially solves the convergence-control mismatch (VAC) problem, making the Maxwellian display attractive. The disadvantage of Maxwellian displays is that the eyebox is limited by the pupil size.

Techniques have been reported to magnify the eyebox by adjusting the focal point using a dynamic mirror or generating multiple focuses using a Holographic Optical Element (HOE), but these methods require mechanical movement or multiple Since the position of the focal point is still fixed, its usefulness is limited.

Holographic proximity-eye-display (NED) is another approach. This method completely solves the convergence-control mismatch (VAC) problem by reconstructing the wavefront of a 3D object at an arbitrary distance. Due to these advantages, various studies on holographic proximity-eye-display (NED) have been actively conducted. However, since the spatial bandwidth product (SBP) of the currently available spatial light modulator (SLM) is not sufficient, the eyebox of the near-eye-display (NED) configuration is limited.

J.-H. Park, "Recent progresses in computer generated holography for three-dimensional scene," J. Inf. Disp. 18(1), 1-12 (2017).

Embodiments describe a holographic head mounted display device capable of adjusting the image depth and the position of the eye and a display method using the same, and more specifically, controlling the depth of field of each virtual 3D image and using the dynamic adjustment to adjust the eyebox Provided is a technology for a reproducible optical see-through holographic proximity eye display device.

Embodiments use a holographic optical element (HOE) that functions as a multiplexed concave mirror that replicates the eyebox, allowing images to be viewed over a wider range and depth of field of the displayed 3D subject individually. To provide a holographic head-mounted display device capable of controlling image depth and eye position, which can be generated by controlling computer-generated holograms (CGH) in different ranges of an angular spectrum, and a display method using the same.

A holographic head mounted display device according to an embodiment includes: a spatial light modulator (SLM) in which a plane wave from a laser source is modulated by a computer generated hologram (CGH); A 4f optical unit that modulates the spatial light modulator (SLM) to form an intermediate holographic image; And light from the intermediate holographic image, including a reflective holographic optical element (HOE) that diffracts to provide an enlarged virtual holographic image at a greater distance than the user's eye.

The holographic optical element HOE is recorded so that oblique plane waves from the spatial light modulator SLM are diffracted to form multiple focal points, and can function as a multiplexed oblique concave mirror.

The separation distance between the focal points of the holographic optical element (HOE) is set slightly larger than the eye pupil size, and around each of the focal points, the eyebox is an angular spectrum used for the computer generated hologram (CGH) synthesis. It can be formed to a size determined by the range.

The light corresponding to the virtual holographic image is replicated toward the multi-focus point by the holographic optical element (HOE), so that the eye located in any eyebox can see the displayed image.

A display method using a holographic head mounted display device according to another embodiment includes the steps of: a plane wave from a laser source being modulated by a computer generated hologram (CGH) of a spatial light modulator (SLM); After the modulation, forming an intermediate holographic image after the 4f optic; And light from the intermediate holographic image is diffracted by a reflective holographic optical element (HOE) to provide an enlarged virtual holographic image at a greater distance than the user's eye.

According to embodiments, it is possible to provide a holographic head mounted display device capable of adjusting focus without mechanical movement by controlling the depth of field of each virtual 3D image and replicating the eye box using dynamic adjustment, and a display method using the same have.

According to embodiments, a holographic optical element (HOE), which functions as a multiplexed concave mirror replicating an eyebox, allows images to be viewed over a wider range, and the depth of field of the displayed 3D subject. It is possible to provide a holographic head-mounted display device capable of controlling image depth and position of an eye and a display method using the computer-generated hologram (CGH) that can be individually controlled to be generated in different ranges of the angular spectrum.

1 is a view for explaining a holographic head mounted display device according to an embodiment.
2 is a flowchart illustrating a display method using a holographic head mounted display device according to an embodiment.
3 is a diagram for explaining computer-generated hologram (CGH) synthesis according to an embodiment.
4 is a diagram illustrating a coordinate system of a holographic optical element (HOE) and a spatial light modulator (SLM) according to an embodiment.

Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the described embodiments may be modified in various other forms, and the scope of the present invention is not limited by the embodiments described below. In addition, various embodiments are provided to more fully describe the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for a more clear description.

The following embodiments relate to a new holographic Near-Eye-Display (NED) device, more specifically, an optical type having eyebox adjustment and depth of field control. A technique for see-through holographic proximity eye display is proposed.

The holographic head mounted display device according to an embodiment may use a holographic optical element (HOE) functioning as a multiplexed concave mirror replicating an eye box to view an image in a wider range. Can be made. By individually controlling the depth of field of the displayed 3D object, a computer generated hologram (CGH) may be generated in different ranges of the angular spectrum.

Therefore, it is possible to display a 3D scene composed of a holographic 3D image at an arbitrary distance of a shallow depth of field, such as a general holographic display device, and without time-multiplexing, it is possible to display a normal Maxwellian display device. It is possible to display an image that is always in focus at the same large depth of field. Angular spectral control adjusts the focal point in the Maxwellian view, making it robust to pupil changes and eye rotation. The combination of analog holograms, or holographic optical elements (HOEs) with multiplexed oblique concave mirrors and digital holographic display technology, is larger than the limits of the conventional spatial bandwidth product (SBP) of the spatial light modulator (SLM). Contributes to the expansion of the box.

Next, a configuration of a holographic head mounted display device according to an embodiment will be described using optical test results verifying feasibility.

1 is a view for explaining a holographic head mounted display device according to an embodiment.

Referring to FIG. 1, the holographic head mounted display device 100 according to an embodiment includes a spatial light modulator (SLM, 120), a 4f optical unit 130, and a holographic optical element (HOE, 140). It is possible to adjust the depth of the image and the position of the eyes.

The spatial light modulator (SLM, 120) may be a plane wave from the laser source 110 is modulated by a computer generated hologram (CGH).

After the 4f optical unit 130 is modulated by the spatial light modulators SLM 120, an intermediate holographic image A may be formed.

The holographic optical elements HOE 140 may diffract light from the intermediate holographic image A to provide an enlarged virtual holographic image B at a greater distance than the user's eyes.

Here, the holographic optical element HOE 140 is recorded so that oblique plane waves from the spatial light modulators SLM 120 are diffracted to form multiple focal points, and can function as a multiplexed oblique concave mirror.

The separation distance between the focal points of the holographic optical element (HOE 140) is set slightly larger than the eye pupil size, and around each focal point, the eyebox 150 is used for computer generated hologram (CGH) synthesis. It can be formed to a size determined by the angular spectral range.

The light corresponding to the virtual holographic image B is replicated toward the multi-focus point by the holographic optical element HOE 140, so that the eye located in any eyebox 150 can see the displayed image. .

It should be noted that the generation of multiple focal points by holographic optical elements (HOE 140) is not achieved by higher order diffraction. The holographic optical element HOE 140 can be recorded as a single signal waveform that converges at multiple focal points. Accordingly, the holographic head-mounted display apparatus 100 according to an embodiment may use first-order diffraction of the holographic optical elements HOE 140 generating a plurality of points.

Hereinafter, the holographic head mounted display apparatus 100 will be described in more detail.

2 is a flowchart illustrating a display method using a holographic head mounted display device according to an embodiment.

Referring to FIG. 2, in a display method using a holographic head mounted display device according to an embodiment, a plane wave from a laser source is modulated by a computer generated hologram (CGH) of a spatial light modulator (SLM) (S110) , After modulation, forming an intermediate holographic image after the 4f optic (S120), and the light from the intermediate holographic image is diffracted and enlarged by a reflective holographic optical element (HOE). It may be made by including the step (S130) of providing a distance greater than the user's eyes.

According to the embodiments, it is possible to adjust the focus without mechanical movement by controlling the depth of field of each of the virtual 3D images and replicating the eye box using dynamic adjustment.

In particular, images can be observed over a wider range using a holographic optical element (HOE) that functions as a multiplexed concave mirror that duplicates the eyebox. In addition, the computer generated hologram (CGH) may be generated in different ranges of the angular spectrum by individually controlling the depth of field of the displayed 3D object.

Hereinafter, a display method using a holographic head mounted display device according to an embodiment will be described as an example.

A display method using a holographic head mounted display device according to an embodiment may be described in more detail using a holographic head mounted display device according to an embodiment described above. The holographic head mounted display device according to an embodiment may include a spatial light modulator (SLM), a 4f optical unit, and a holographic optical element (HOE).

In step S110, the plane wave from the laser source may be modulated by the computer-generated hologram CGH of the spatial light modulator SLM.

In step S120, after modulating by the computer-generated hologram CGH of the spatial light modulator SLM, an intermediate holographic image may be formed after the 4f optical unit.

In step S130, the light from the intermediate holographic image may be diffracted by the reflective holographic optical element (HOE) to provide an enlarged virtual holographic image at a greater distance than the user's eye.

Here, the holographic optical element (HOE) is recorded so that oblique plane waves from the spatial light modulator (SLM) are diffracted to form multiple focal points, and can function as a multiplexed oblique concave mirror. The separation distance between the holographic optical element (HOE) focal points may be set slightly larger than the eye pupil size. Around each focal point, the eyebox can be formed to a size determined by the angular spectral range used for computer generated hologram (CGH) synthesis. Since the light corresponding to the virtual holographic image is replicated toward the multi-focus point by the holographic optical element (HOE), the eye located in any eyebox can see the displayed image.

According to embodiments, a holographic optical element (HOE), which functions as a multiplexed concave mirror replicating an eyebox, allows images to be viewed over a wider range, and the depth of field of the displayed 3D subject. By individually controlling, computer-generated holograms (CGH) can be generated in different ranges of the angular spectrum.

Hereinafter, a holographic head mounted display device and a display method using the same according to an embodiment will be described in more detail.

Depth-of-field control of individual holographic images

In a holographic head mounted display device according to an embodiment, the depth of field of an individual holographic image may be controlled by an angular spectral range used for the synthesis of the corresponding computer generated hologram (CGH). In the maximum angular spectral range limited by the pixel pitch of the spatial light modulator (SLM), the effective eyebox for the image has a maximum size, so that the depth of field can be minimized around a specified distance of the holographic image. In the minimum angular spectral range, the depth of field can always be maximized to provide a focused image.

평면에 위치하고 단일 삼각형 조리개가 3개의 정점 중 하나를 갖는

평면에 위치하도록, 즉

가 로컬 좌표 원점에 위치하도록, 글로벌

및 로컬

좌표 시스템이 정의된다고 가정한다. 단일 삼각형 조리개

의 각도 스펙트럼은 다음 식과 같이 주어질 수 있다.Computer-generated hologram (CGH) synthesis using angular spectral range control can be achieved using several types of computer-generated holograms (CGH) (Non-Patent Document 1). In an implementation according to an embodiment, an analytical triangular mesh based computer generated hologram (CGH) technique is used for direct control of the angular spectrum in computer generated hologram (CGH) synthesis. In an analytical triangular mesh-based computer-generated hologram (CGH), a 3D object is modeled as a set of clear apertures of a triangular shape illuminated by a carrier. Hologram

Located on a plane and a single triangular aperture has one of the three vertices

To be on the plane, i.e.

Global, so that is located at the local coordinate origin

And local

Assume that a coordinate system is defined. Single triangle aperture

The angular spectrum of can be given by the following equation.

[Equation 1]

및

는 글로벌 좌표계 시스템의 공간 주파수의

및

벡터이다.

은 로컬 좌표계 시스템의 공간 주파수 벡터이며, 로컬 좌표계 시스템은

회전 행렬 R을 사용하는

에 의한 글로벌 공간 주파수 벡터

과 관련된다. 두 개의 공간 주파수 벡터

및

은

을 만족하며,

는 파장이다.

는

에 의해 주어지는

벡터이다.

은 이진 함수

의 푸리에 변환이다. 이진 함수

은 기준 삼각형 내부에서 1이며 외부에서 0이다. A는

에 의해 로컬 평면에서 삼각형 조리개를 기준 삼각형에 관련시키는

행렬이다. 그리고

는

에 대한 컨볼루션을 나타낸다.here,

And

Of the spatial frequency of the global coordinate system

And

It is a vector.

Is the spatial frequency vector of the local coordinate system, and the local coordinate system is

Using the rotation matrix R

Global space frequency vector by

It is related to. Two spatial frequency vector

And

silver

Satisfying,

Is the wavelength.

The

Given by

It is a vector.

Is a binary function

Is the Fourier transform. Binary function

Is 1 inside the reference triangle and 0 outside. A is

By relating the triangular aperture to the reference triangle in the local plane

It is a matrix. And

The

Represents the convolution for.

는 아래와 같이 정의되는 수학식 1의

항을 조절하여 연산될 수 있으며, 다음 식과 같이 나타낼 수 있다.Angle spectrum of holographic image

Equation 1 defined as follows

It can be calculated by adjusting terms, and can be expressed as the following equation.

[Equation 2]

는 반송파의 각도 스펙트럼이다. here,

Is the angular spectrum of the carrier.

3 is a diagram for explaining computer-generated hologram (CGH) synthesis according to an embodiment.

인 단일 평면 반송파의 경우, 홀로그래픽 이미지의 각도 스펙트럼

는, 도 3 (a)의 좌측에 도시된 바와 같이, 3D 피사체의 공간 대역폭과 평면파

의 공간 주파수 주위에 집중되어 있다. 눈동자 평면에서, 홀로그래픽 이미지의 좁은 각도 스펙트럼은, 도 3 (a)의 우측에 도시된 바와 같이, 홀로그래픽 광학 소자(HOE)에 의해 복제된 초점 지점으로 변환된다. 초점 지점의 폭은 눈동자보다 훨씬 작으므로, 가상의 홀로그래픽 이미지는 사용자 눈의 실제 초점 거리에 관계없이 항상 초점이 맞춰진 큰 피사계 심도로 보여진다.

In the case of a single plane carrier, the angular spectrum of the holographic image

As shown in the left side of Fig. 3 (a), the spatial bandwidth and the plane wave of the 3D object

It is concentrated around the spatial frequency. In the pupil plane, the narrow angular spectrum of the holographic image is transformed into a focal point replicated by the holographic optical element (HOE), as shown on the right side of Fig. 3(a). Since the width of the focal point is much smaller than the pupil, the virtual holographic image is always shown with a large depth of focus, regardless of the actual focal length of the user's eye.

에 대해

가 되도록 하는 반송파로서 사용되면, 도 3 (b)의 좌측에 도시된 바와 같이, 홀로그래픽 이미지의 각도 스펙트럼이 확장되고, 도 3 (b)의 우측에 도시된 바와 같이, 눈동자 평면 내의 홀로그래픽 광학 소자(HOE)에 의해 확장된 폭이 형성된다. 충분히 넓은 범위의 평면 반송파를 사용하면, 아이박스 폭이 눈동자보다 크므로, 재구성을 위해 관찰 가능한 최소 피사계 심도가 제공된다.Conversely, the range of a plane wave

About

When used as a carrier to be, the angular spectrum of the holographic image is expanded, as shown on the left side of Fig. 3(b), and the holographic optics in the pupil plane, as shown on the right side of Fig. 3(b) An extended width is formed by the element HOE. Using a sufficiently wide range of planar carriers, the eyebox width is larger than the pupil, providing a minimum observable depth of field for reconstruction.

This angle spectrum control can be performed for each triangular aperture of the subject or for each 3D subject of the entire scene. Therefore, it is possible to reconstruct a 3D image having a different depth of field for each subject.

Focus point adjustment for always-focused images

에 의존하기 때문에, 다중 초점 지점은 컴퓨터 생성 홀로그램(CGH) 합성에서

의 변화를 통해 그들의 분리를 유지하면서 조정될 수 있다. 초점 지점 분리는 눈동자 크기보다 약간 크게 설정되기 때문에, 눈 추적 시스템에 의해 그 위치가 검출되면, 눈동자에 단일 초점 지점을 투사하는 것이 가능하다. 이 특징은 일 실시예에 따른 홀로그래픽 헤드 마운티드 디스플레이 장치가 종래의 맥스웰(Maxwellian) 디스플레이 장치 보다 눈동자의 크기 변화 및 안구 회전에 대해 더욱 강건해지게 한다.In the case of a single plane carrier, the displayed image is always focused, just like a typical Maxwellian display device. However, it is noteworthy that the holographic head mounted display device according to one embodiment can adjust the focus without any mechanical movement. Focus adjustment in a holographic head mounted display device according to an embodiment is simply performed by synthesizing a computer generated hologram (CGH) with different single plane carriers. A single plane wave is diffracted to form multiple focal points by a holographic optical element (HOE), and the lateral position offset within the pupil plane is the spatial frequency of the plane carrier.

Because it depends on the multi-focus point in computer generated hologram (CGH) synthesis

The changes can be adjusted while maintaining their separation. Since the focal point separation is set slightly larger than the pupil size, it is possible to project a single focal point into the pupil if its position is detected by the eye tracking system. This feature makes the holographic head mounted display device according to an embodiment more robust to eye size changes and eye rotation than a conventional Maxwellian display device.

Aberration correction of holographic optical elements (HOE)

In a holographic head-mounted display device according to an embodiment, the holographic optical element (HOE) functions as a concave mirror, which can magnify an intermediate holographic image that forms its own virtual image at a distance. . Due to the tilted configuration and large magnification as shown in Fig. 1, the formed virtual image undergoes large aberration. The holographic head mounted display device according to an embodiment may precompensate the aberration to form a virtual image in a clear shape.

4 is a diagram illustrating a coordinate system of a holographic optical element (HOE) and a spatial light modulator (SLM) according to an embodiment.

만큼 기울어진 공간 광 변조기(SLM)으로부터의 평면파가 회절되어 거리

에서 지점을 형성하도록 기록된다. 홀로그래픽 광학 소자(HOE) 평면

내의 각각의 점에 대하여, 자유 공간 격자 벡터

는 다음 식과 같이 나타낼 수 있다. Referring to FIG. 4, the holographic optical element (HOE) is angled relative to the holographic optical element (HOE) plane.

The distance from the plane wave diffracted from the spatial light modulator (SLM) tilted by

It is recorded to form a point at. Holographic optical element (HOE) plane

For each point within, a free space grid vector

Can be expressed as the following equation.

[Equation 3]

는 자유 공간

에서의 파수(wave number)이다. 홀로그래픽 광학 소자(HOE) 매체 내부의 실제 격자 벡터는 이 매체의 굴절률로 인하여 수학식 3의 자유 공간 격자 벡터 K와는 다르다. 그럼에도 불구하고, 자유 공간 격자 벡터 K를 사용한 다음과 같은 분석은 자유 공간에서의 모든 파동 벡터 및 위상 분포에 대해 여전히 유효하다.here,

Is free space

It is the wave number in Esau. The actual grating vector inside the holographic optical element (HOE) medium is different from the free space grating vector K in Equation 3 due to the refractive index of the medium. Nevertheless, the following analysis using free space lattice vector K is still valid for all wave vectors and phase distributions in free space.

에 가상 이미지 포인트를 형성하기 위해, 자유 공간에서 회절된 광의 파동 벡터

이 다음 식과 같이 나타낼 수 있다. In the reconstruction, as shown in Figure 4,

Wave vector of light diffracted in free space to form a virtual image point on

It can be expressed as the following equation.

[Equation 4]

를 유도할 수 있으며, 다음 식과 같이 나타낼 수 있다.Equation 4 above is the corresponding wave vector of the incident light from the spatial light modulator (SLM)

And can be expressed as the following equation.

[Equation 5]

[Equation 6]

의 해당 위상 분포를 찾을 수 있으며, 다음 식과 같이 나타낼 수 있다.From Equation 5 and Equation 6, we enter the holographic optical element (HOE) plane incidence light, as shown below.

The corresponding phase distribution of can be found and can be expressed as the following equation.

[Equation 7]

및

는 유도(미분)에 사용된다. In the above equation,

And

Is used for induction (differentiation).

의 축간 오목 거울에서의 단일 포인트 이미지 형성의 위상 함수에 불과하다. 따라서 틸트에 의해 야기되는 수차를 보상하기 위해 고려해야 할 것은 각도 스펙트럼 영역에서 공간 주파수

축을 따라

에 의한 시프트에 해당하는 세 번째 항

이다. The first two terms on the right side of equation (7) are the focal length

It is only a phase function of single point image formation in the interaxial concave mirror of. Therefore, to compensate for the aberration caused by the tilt, the spatial frequency in the angular spectrum region

Along the axis

Third term corresponding to shift by

to be.

를 가지는 홀로그래픽 광학 소자(HOE) 평면의 각도 스펙트럼은

에 의한 일반적인 축 상(on-axis) 각도 스펙트럼

와 관련된다.For normal intermediate holographic 3D images, tilt aberration correction

The angular spectrum of a holographic optical element (HOE) plane having

Typical on-axis angular spectrum by

Related to.

가 결정되면, 공간 광 변조기(SLM) 평면에서의 대응하는 각도 스펙트럼

이 두 평면 사이의 기하학적 관계로부터 얻어진다. 보다 구체적으로, 공간 광 변조기(SLM) 평면

의 각도 스펙트럼은 (비특허문헌 1)에 의해 다음 식과 같이 나타낼 수 있다. Angle spectrum from the desired intermediate holographic image

Is determined, the corresponding angular spectrum in the spatial light modulator (SLM) plane

It is obtained from the geometric relationship between these two planes. More specifically, a spatial light modulator (SLM) plane

The angle spectrum of can be expressed by the following equation by (Non-Patent Document 1).

[Equation 8]

In Equation 8 above,

[Equation 9]

이며,

And

이다.

to be.

내에서의 각도 스펙트럼이 공간 광 변조기(SLM)의 공간 주파수 그리드

에서 획득할 수 있다. 수학식 8의

은 홀로그래픽 광학 소자(HOE)에 의해 확대될 원하는 중간 홀로그래픽 이미지에 대해, 앞에서 설명된 각도 스펙트럼 범위를 고려하여 일반적인 분석 삼각형 메쉬 기반 컴퓨터 생성 홀로그램(CGH) 기법을 사용하여 평가될 수 있다. 공간 광 변조기(SLM) 평면

의 각도 스펙트럼은 최종 복소 진폭, 즉 공간 광 변조기(SLM) 평면 내의 홀로그램을 제공하기 위해 최종적으로 푸리에 변환될 수 있다.In other words, the spatial light modulator (SLM) plane using equation (8)

The angular spectrum within is a spatial frequency grid of a spatial light modulator (SLM)

Can be obtained from Equation 8

For a desired intermediate holographic image to be magnified by a holographic optical element (HOE), it can be evaluated using a general analysis triangle mesh based computer generated hologram (CGH) technique, taking into account the angular spectral range described above. Spatial Light Modulator (SLM) plane

The angular spectrum of can be finally Fourier transformed to provide a final complex amplitude, i.e. a hologram in the spatial light modulator (SLM) plane.

Eyebox size and focus point adjustment range

In the holographic head mounted display apparatus according to an embodiment, the eyebox size and the focal point adjustment range may be determined by the spatial frequency range of the plane carrier.

로 나타내면, 공간 광 변조기(SLM)에 의해 지원되는 공간 주파수 범위는

와 같이 주어지며, 여기서

또는

이다. The pixel pitch of the spatial light modulator (SLM)

Expressed as, the spatial frequency range supported by the spatial light modulator (SLM) is

Is given as, where

or

to be.

에서

및

는

방향의

및

방향의

에 의해 공간 광 변조기(SLM)의 공간 주파수

및

와 관련된다. From Equations 8 and 9, on-axis angular spectrum

in

And

The

Directional

And

Directional

Spatial frequency of spatial light modulator (SLM)

And

Related to.

에 대해 사용 가능한 공간 주파수 범위는

방향에 대해

이며,

방향에 대해

이다. 공간 주파수

를 가지는 평면 파동은 홀로그래픽 광학 소자(HOE) 초점 길이

를 가지는

에서 눈동자로 초점이 맞춰진다. 따라서, 단일 아이박스의 크기 또는 눈동자 평면의 초점 지점 조정 범위는 최종적으로 다음 식과 같이 나타낼 수 있다. therefore,

The available spatial frequency range for

About direction

And

About direction

to be. Spatial frequency

A planar wave having a holographic optical element (HOE) focal length

Having

Is focused with the pupil. Therefore, the size of a single eyebox or the range of adjustment of the focal point of the pupil plane can be finally expressed as the following equation.

[Equation 10]

Equation 10 represents the size of a single eyebox or the adjustment range of a single focal point. The holographic head mounted display device according to an embodiment uses an holographic optical element (HOE) to replicate an eyebox or a focal point, so that the entire range in which the eye can be located is multiplexed.

As mentioned above, for optical see-through and eyebox replication, a holographic optical element is used as an optical combiner, which is a multiplexed tilt concave mirror that forms multiple copies of the eyebox. (multiplexed tilted concave mirrors). For depth-of-field control and eyebox adjustment, a hologram of a computer-generated three-dimensional object is synthesized into different ranges of the angular spectrum.

In optical experiments, it has been found that the holographic head-mounted display device according to one embodiment is capable of always displaying a focused image, which is large at different distances at the same time without time-multiplexing and at a low depth of field. It has a depth of field and a three-dimensional image.

The device described above may be implemented with hardware components, software components, and/or combinations of hardware components and software components. For example, the devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor (micro signal processor), a microcomputer, a field programmable array (FPA), It may be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may run an operating system (OS) and one or more software applications running on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of understanding, a processing device may be described as one being used, but a person having ordinary skill in the art, the processing device may include a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that may include. For example, the processing device may include a plurality of processors or a processor and a controller. In addition, other processing configurations, such as parallel processors, are possible.

The software may include a computer program, code, instruction, or a combination of one or more of these, and configure the processing device to operate as desired, or process independently or collectively You can command the device. Software and/or data may be interpreted by a processing device, or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. Can be embodied in The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded in the medium may be specially designed and configured for the embodiments or may be known and usable by those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. -Hardware devices specifically configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler.

As described above, although the embodiments have been described by a limited embodiment and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques are performed in a different order than the described method, and/or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or other components Alternatively, even if replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (5)

A spatial light modulator (SLM) in which a plane wave from a laser source is modulated by a computer generated hologram (CGH);
A 4f optical unit that modulates the spatial light modulator (SLM) to form an intermediate holographic image; And
Light from the intermediate holographic image is diffracted, a reflective holographic optical element (HOE) that provides an enlarged virtual holographic image at a greater distance than the user's eye
A holographic head mounted display device comprising a. According to claim 1,
The holographic optical element (HOE),
Inclined plane waves from the spatial light modulator (SLM) are diffracted and recorded to form multiple focal points, functioning as a multiplexed inclined concave mirror
Holographic head mounted display device, characterized in that. According to claim 1,
The separation distance between the focal points of the holographic optical element (HOE) is set slightly larger than the eye pupil size, and around each of the focal points, the eyebox is the angular spectrum used for the computer generated hologram (CGH) synthesis. Formed to size determined by range
Holographic head mounted display device, characterized in that. According to claim 1,
The light corresponding to the virtual holographic image is replicated toward the multi-focus point by the holographic optical element (HOE), so that the eye located in any eye box can see the displayed image
Holographic head mounted display device, characterized in that. The plane wave from the laser source is modulated by a computer generated hologram (CGH) of a spatial light modulator (SLM);
After the modulation, forming an intermediate holographic image after the 4f optic; And
The light from the intermediate holographic image is diffracted by a reflective holographic optical element (HOE) to provide an enlarged virtual holographic image at a greater distance than the user's eye.
Display method using a holographic head mounted display device comprising a.

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