WO2024143600A1

WO2024143600A1 - Method for reproducing multi-depth image by using holographic optical element

Info

Publication number: WO2024143600A1
Application number: PCT/KR2022/021465
Authority: WO
Inventors: 홍지수; 홍성희; 김영민; 정진수; 김용화; 이병효; 오현찬
Original assignee: 한국전자기술연구원
Priority date: 2022-12-28
Filing date: 2022-12-28
Publication date: 2024-07-04
Also published as: KR102597352B1

Abstract

A method for reproducing a multi-depth image by using an HOE is provided. An HOE recording method for an HUD capable of reproducing a multi-depth image, according to an embodiment of the present invention, comprises: rotating, in steps, an HOE; adjusting, in steps, the distance between the HOE and the center pixel of a virtual image screen; and recording lens characteristics on the HOE while performing, in steps, rotation and adjustment. Therefore, multi-focus lens characteristics for an HUD are recorded on the HOE while the distance between the HOE and the center pixel of the virtual image screen and the rotating angle of the HOE are adjusted in steps, and thus a HOE-based HUD capable of reproducing a three-dimensional image through the virtual image screen having multiple depths can be implemented.

Description

Multi-depth image reproduction method using holographic optical elements

The present invention relates to technology for utilizing HOE (Holographic Optical Element), and more specifically, to a method of manufacturing a lens for a Heads-Up Display (HUD) using HOE.

As shown in Figure 1, the HUD using HOE uses the HOE on which the lens characteristics (functions) of the HUD are recorded as the front glass, and images the image projected from the projector on the screen located below the HOE onto the virtual screen behind the HOE. It allows the observer to observe an enlarged image from a distance.

At this time, the HOE functions as a lens only for light from the screen direction due to wavelength angle selectivity, so when the observer observes the distant background through the HOE, it functions as a transparent glass window.

Figure 2 shows a method for recording a HOE that performs this function. In the recording of the HOE, the spherical wave emanating from the center pixel position of the real screen below the HOE and the spherical wave emanating from the center pixel position of the virtual screen are recorded by interfering with each other on the HOE plane, thereby imaging the screen center pixel to the center pixel position of the virtual screen. It functions as a lens that

However, through the HOE recorded in this way, the position of the virtual screen is fixed to a flat surface, and therefore, although the HUD image that the observer can observe is an image imaged at a distance, it has the limitation of being a two-dimensional single-plane image.

The present invention was developed to solve the above problems, and the purpose of the present invention is to provide a method of implementing a HOE-based HUD capable of playing 3D images through a virtual screen image with multiple depths.

In order to achieve the above object, the HOE recording method according to an embodiment of the present invention includes the steps of gradually rotating a Holographic Optical Element (HOE); Steppingly adjusting the distance between the center pixel of the virtual screen and the HOE; and recording lens characteristics in the HOE while the rotation step and the adjustment step are performed step by step.

The adjustment step may be stepwise adjusting the distance between the center pixel of the virtual screen and the HOE to a first distance, a second distance, ..., an N-th distance.

The rotation step may be to gradually adjust the rotation angle of the HOE to 0°, 1*360°/N, ..., (N-1)*360°/N.

The recording step includes a first irradiation step of radiating a spherical wave from the center pixel of the virtual image screen to the HOE; It may include a second irradiation step of radiating a spherical wave from the center pixel of the actual screen to the HOE.

The first irradiation step may be irradiating a spherical wave through a first pinhole located at the center pixel of the virtual screen.

In the first irradiation step, a first lens spaced apart from the first pinhole by a focal distance may focus the incident parallel laser light onto the first pinhole.

The second irradiation step may be irradiating a spherical wave through a second pinhole located at the center pixel of the actual screen.

In the second irradiation step, a second lens spaced apart from the second pinhole by a focal distance may focus the incident parallel laser light onto the second pinhole.

Lens characteristics may be characteristics of a multi-focus lens for implementing a multi-depth HUD.

According to another aspect of the present invention, a HOE (Holographic Optical Element) rotated in stages; A pinhole located at the center pixel of the virtual screen where the distance between HOEs is adjusted in steps; A light source emitting a parallel beam; A HOE recording device is provided that includes a lens that focuses the parallel beam emitted from the light source into a pinhole and emits it to the HOE.

According to another aspect of the present invention, rotating a Holographic Optical Element (HOE); A step of projecting the corresponding depth image according to the rotation angle of the HOE; wherein the HOE is rotated step by step and the distance to the center pixel of the virtual image screen is adjusted step by step, and the lens characteristics are recorded. Image reproduction. A method is provided.

According to another aspect of the present invention, a rotating means for rotating a HOE (Holographic Optical Element); A projector that projects the corresponding depth image according to the rotation angle of the HOE; and an image reproduction device, wherein the HOE is rotated step by step and the distance to the center pixel of the virtual screen is adjusted step by step and the lens characteristics are recorded. A method is provided.

As described above, according to embodiments of the present invention, the distance between the center pixel of the virtual image screen and the HOE and the rotation angle of the HOE are gradually adjusted and the multi-focus lens characteristics for the HUD are recorded in the HOE, thereby creating a virtual image with multiple depths. It is possible to implement a HOE-based HUD that can play 3D images through screen images.

Figure 1. Existing HOE-based HUD

Figure 2. HOE recording method for existing HUD

Figures 3 and 4. HOE recording method capable of playing multi-depth images according to an embodiment of the present invention

Figure 5. Sequence of HOE recording method according to an embodiment of the present invention

Figure 6. HUD implementation method for playing multi-depth images

Figure 7. Sequence of HUD multi-depth image playback method according to another embodiment of the present invention

Hereinafter, the present invention will be described in more detail with reference to the drawings.

An embodiment of the present invention presents a multi-depth image reproduction method using a Holographic Optical Element (HOE). This is a technology that allows HOE-based HUD (Heads-Up Display) to display images on a virtual screen with multiple depths, rather than only showing a two-dimensional, single-plane image.

3 and 4 are diagrams provided to explain a HOE recording method for a HUD capable of playing multi-depth images according to an embodiment of the present invention. In an embodiment of the present invention, the HOE 200 aims to reproduce multi-depth images on virtual screens located at distances D ₁ , D ₂ , D ₃ , ... D _N .

As shown in Figure 3, recording of HOE 200 begins by first recording the interference of a spherical wave from the center pixel of the virtual screen located at a distance D ₁ and a spherical wave from the center pixel position of the real image screen below.

For this purpose, pinhole 1 (120) is located at the center pixel of the virtual screen, and a collimated laser beam emitted from a light source (not shown) is transmitted through the lens 110 to pinhole 1 spaced apart by the focal distance (f). By focusing on (120), the spherical wave is emitted from pinhole 1 (120) to the HOE (200). The spherical wave emitted from pinhole 1 (120) to the HOE (200) corresponds to the reference beam.

Then, pinhole 2 (130) is located at the center pixel of the actual screen, and the parallel laser beam emitted from the light source (not shown) is focused on pinhole 2 (130) spaced apart by the focal distance f through the lens 140. , so that a spherical wave is emitted from pinhole 2 (130) to the HOE (200). The spherical wave emitted from pinhole 2 (130) to the HOE (200) corresponds to object beam.

Afterwards, as shown in FIG. 4, the angle of the HOE (200) is rotated by 360°/N, and the distance of the spherical wave from the direction of the virtual screen, that is, the distance from the HOE (200) to pinhole 1 (120), is D ₂ After changing to , record the interference pattern with the spherical wave from the center pixel of the lower real screen.

In the same way, the HOE (200) is rotated by 360°/N, the distance of the spherical wave in the direction of the virtual screen is sequentially changed to D ₃ , ... D _N , and the interference pattern is overlapped and recorded in the HOE (200). The HOE 200 for which recording has been completed can function as a HUD lens in which lenses of various focal lengths are multiplexed due to wavelength angle selectivity.

Figure 5 is a flowchart showing the sequence of the HOE recording method according to an embodiment of the present invention.

As shown, the HOE 200 is first rotated step by step (S310). Specifically, in step S310, the rotation angle of the HOE 200 is adjusted step by step to 0°, 1*360°/N, ..., (N-1)*360°/N.

In addition, the distance between pinhole 1 (120) and the HOE (200) located at the center pixel of the virtual screen is adjusted step by step according to step S310 (S320). Specifically, in step S320, the distance between pinhole 1 (120) and HOE (200) is adjusted step by step to D ₁ , D ₂ , ... D _N .

And while steps S310 and S320 are performed step by step, the multi-focus lens characteristics of the HUD are recorded in the HOE 200 (S330). Step S330 is a process of irradiating reference light from pinhole 1 (120), the center pixel of the virtual screen, to the HOE (200), and irradiating object light from pinhole 2 (130), the center pixel of the real screen, to the HOE (200). all.

Steps S310 to S330 are repeated until the step-by-step rotation of the HOE 200 is completed and returns to the original rotation angle (0°) (S340).

Hereinafter, a method of implementing a HUD capable of playing multi-depth images using the HOE 200 recorded according to the above embodiment will be described in detail with reference to FIG. 6. Figure 6 is a diagram provided to explain a HUD capable of playing multi-depth images according to another embodiment of the present invention.

As shown, a screen 350 is placed at the bottom of the HOE 200 recorded according to the above embodiment, and then an image is projected through the projector 300.

The image projected from the projector 300 is imaged and displayed on a virtual screen by the HOE 200. At this time, the distance from the HOE (200) of the virtual screen image changes each time the angle of the HOE (200) is rotated, and the distance becomes D ₁ , D ₂ , ... D _N , which are the spherical wave departure distances at the time of recording. .

Therefore, if the HOE 200 is rotated at high speed and the projector 30 projects a depth image synchronized to the angle of the HOE 200, a set of virtual screen images located at a number of distances, that is, a multi-depth image, is created due to the afterimage effect. You can show videos.

Figure 7 is a flowchart showing the sequence of a HUD multi-depth image playback method according to another embodiment of the present invention.

As shown, first, the HOE (200) is rotated at high speed (S410). For step S410, a HOE rotation means (not shown) is required. The projector 30 projects the corresponding depth image according to the rotation angle of the HOE 200 (S420).

Specifically, in step S420, 1) when the rotation angle of the HOE (200) is 0°, a depth image with a distance of D ₁ between the virtual screen and the HOE (200) is displayed, and 2) when the rotation angle is 1*360°/N, a virtual A depth image with a distance of D ₂ between the screen and the HOE (200), 3) When the rotation angle is 2*360°/N, a depth image with a distance of D ₃ between the virtual screen and the HOE (200), ... N ) When the rotation angle is (N-1)*360°/N, a depth image with a distance D _N between the virtual screen and the HOE 200 is synchronized to be projected.

As a result, the corresponding depth images are displayed on virtual screens at different distances (S430).

So far, a method for reproducing multi-depth images in a HUD using HOE has been described in detail with preferred embodiments.

In the above embodiment, the distance between the center pixel of the virtual screen and the HOE and the rotation angle of the HOE are gradually adjusted while recording multi-focus lenses on the HOE, thereby creating a HOE-based HUD capable of playing 3D images through a virtual screen image with multiple depths. made it possible to implement.

Meanwhile, of course, the technical idea of the present invention can be applied to a computer-readable recording medium containing a computer program that performs the functions of the device and method according to this embodiment. Additionally, the technical ideas according to various embodiments of the present invention may be implemented in the form of computer-readable code recorded on a computer-readable recording medium. A computer-readable recording medium can be any data storage device that can be read by a computer and store data. For example, of course, computer-readable recording media can be ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical disk, hard disk drive, etc. Additionally, computer-readable codes or programs stored on a computer-readable recording medium may be transmitted through a network connected between computers.

In addition, although preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be understood individually from the technical idea or perspective of the present invention.

Claims

Stepwise rotating the Holographic Optical Element (HOE);

Steppingly adjusting the distance between the center pixel of the virtual screen and the HOE;

A HOE recording method comprising: recording lens characteristics in the HOE while the rotation step and the adjustment step are performed step by step.
In claim 1,

The adjustment step is,

A HOE recording method characterized by stepwise adjusting the distance between the center pixel of the virtual screen and the HOE to a first distance, a second distance, ..., an N-th distance.
In claim 2,

The rotation stage is,

HOE recording method characterized by stepwise adjusting the rotation angle of the HOE to 0°, 1*360°/N, ..., (N-1)*360°/N.
In claim 3,

The recording phase is:

A first irradiation step of radiating a spherical wave from the center pixel of the virtual image screen to the HOE;

A HOE recording method comprising a second irradiation step of irradiating a spherical wave from the center pixel of a real screen to the HOE.
In claim 4,

The first investigation stage is,

A HOE recording method characterized in that irradiating a spherical wave through a first pinhole located at the center pixel of a virtual screen.
In claim 5,

The first investigation stage is,

A HOE recording method characterized in that a first lens spaced apart from the first pinhole by a focal distance focuses the incident parallel laser light onto the first pinhole.
In claim 4,

The second investigation stage is,

A HOE recording method characterized by irradiating a spherical wave through a second pinhole located at the center pixel of the real screen.
In claim 7,

The second investigation stage is,

A HOE recording method characterized in that a second lens spaced apart from the second pinhole by a focal distance focuses the incident parallel laser light onto the second pinhole.
In claim 1,

The lens characteristics are,

HOE recording method characterized by the characteristics of a multi-focus lens for implementing a multi-depth HUD.
Step-rotated Holographic Optical Element (HOE);

A pinhole located at the center pixel of the virtual screen where the distance between HOEs is adjusted in steps;

A light source emitting a parallel beam;

A HOE recording device comprising a lens that focuses the parallel beam emitted from the light source into a pinhole and emits it to the HOE.
Rotating the Holographic Optical Element (HOE);

Including: projecting the corresponding depth image according to the rotation angle of the HOE,

HOE is,

An image playback method characterized in that lens characteristics are recorded while being rotated step by step and the distance to the center pixel of the virtual image screen is adjusted step by step.
Rotating means for rotating HOE (Holographic Optical Element);

Includes a projector that projects the corresponding depth image according to the rotation angle of the HOE,

HOE is,

An image playback method characterized in that lens characteristics are recorded while being rotated step by step and the distance to the center pixel of the virtual image screen is adjusted step by step.