Optical system using geometric phase lens, device thereof, and operation method thereof

Abstract

According to an embodiment of the present invention, disclosed are an optical device and an operating method of the optical device. The optical device comprises: a polarization control unit controlling a polarization state of light; a phase lens unit which changes the polarization state of light emitted from the polarization control unit; and a polarization selection unit which selectively transmits light that has passed through the phase lens unit.

Description

Optical system, device and operating method using geometric phase lens

[0001] The present disclosure relates to an optical system of a VR / AR / MR HMD, and more particularly, to a focus and depth variable optical system.

[0002] In VR / AR / MR HMDs, discrepancies between the depth information perceived by the actual user and the distance at which the virtual image is formed can cause eye fatigue and headaches. One solution to this focus-convergence mismatch problem is variable focus and depth-of-field optics, which enable virtual image depth information to correspond to the distance perceived by the user as the focal plane.

[0003] The existing geometric phase lens (GPL) is a geometric phase lens (HWP GPL) made of a phase delay plate structure based on a half waveplate (HWP).

[0004] These HWP GPLs function as convex or concave lenses depending on the incident circular polarization conditions, and are composed of polarization switching layers and stacked modules. These modules can be manufactured in an extremely thin and lightweight form, and because they allow for polarization-based variable operation, they have the advantage of improving the form factor in all optical systems requiring variable depth of focus. However, despite these advantages, in the case of multi-stage focus and variable depth optical systems utilizing the characteristics of existing HWP GPLs, stacking multiple HWP GPL modules is inevitable to increase the number of virtual image depth planes that can be expressed. Accordingly, there is a need for the development of a new type of geometric phase lens that can form more variable focus steps even with a single GPL.

[0005] The purpose of the present invention is to implement a multi-stage variable depth of focus optical system and optical module utilizing a quarter wave plate based geometric phase lens (QWP GPL).

[0006] According to an embodiment of the present invention, an optical device may be provided, including a polarization control unit that controls the polarization state of light, a phase lens unit that changes the polarization state of light emitted from the polarization control unit, and a polarization selection unit that selectively transmits light passing through the phase lens unit.

[0007] In addition, the device may further include a linear polarizing unit that linearly polarizes light output from a light source, and an optical device that causes light emitted from the linear polarizing unit to enter the polarization control unit.

[0008] In addition, the polarization control unit can modulate the incident linear polarization into circular polarization of left-handed circular polarization rotating counterclockwise or right-handed circular polarization rotating clockwise.

[0009] Additionally, the polarization control unit may include a quarter-wave plate and a switchable half-wave plate.

[0010] In addition, the switchable half-wave plate can modulate the polarization direction of circularly polarized light incident on the phase lens unit to right circular polarization or left circular polarization based on the driving state.

[0011] In addition, the phase lens unit may include a quarter-wave plate-based geometric phase lens (QWP GPL, Quarter-Wave Plate Geometric Phase Lens).

[0012] In addition, the polarization selection unit may include a 1 / 4 wavelength plate, a switchable half-wave plate (Switchable HWP, Half-Wave Plate), and a linear polarizing plate.

[0013] In addition, the polarization selection unit can selectively filter one of the two wavefronts emitted from the phase lens unit based on the operating state (field-on, field-off) of the switchable half-wave plate (switchable HWP).

[0014] In addition, the optical device may include a plurality of optical modules, and each of the plurality of optical modules may include a polarization control unit that controls the polarization state of light, a phase lens unit that changes the polarization state of light emitted from the polarization control unit, and a polarization selection unit that selectively transmits light passing through the phase lens unit.

[0015] According to an embodiment of the present invention, an operating method of an optical device may include a step of a polarization control unit controlling a polarization state of light, a step of a phase lens unit changing a polarization state of light emitted from the polarization control unit, and a step of a polarization selection unit selectively transmitting light passing through the phase lens unit.

[0016] In addition, the method of operating an optical device may further include a step of linearly polarizing light output from a light source by a linear polarizing unit and a step of causing light output from the linear polarizing unit to be incident on the polarization control unit.

[0017] In addition, the step of controlling the polarization state of light by the polarization control unit may include a step of modulating the incident linear polarization into circular polarization of left-handed circular polarization rotating counterclockwise or right-handed circular polarization rotating clockwise.

[0018] In addition, the step of controlling the polarization state of light by the polarization control unit may include a step of modulating the polarization direction of circularly polarized light incident on the phase lens unit to right circular polarization or left circular polarization based on the driving state of the switchable half-wave plate.

[0019] In addition, the step of selectively transmitting light passing through the phase lens unit by the polarization selection unit may include a step of selectively filtering one of two wavefronts emitted from the phase lens unit based on the operating state (field-on, field-off) of a switchable half-wave plate (switchable HWP).

[0020] In addition, an augmented reality device according to an embodiment of the present invention may include an augmented reality device including a display that outputs light forming an image, a polarization control unit that adjusts a polarization state of the light, a phase lens unit that changes a polarization state of the light emitted from the polarization control unit, a polarization selection unit that selectively transmits light passing through the phase lens unit, and a beam splitter that reflects or transmits light passing through the polarization selection unit and provides it to a user.

[0021] In addition, the module having a multi-stage focus and depth variable function in the form of a combination of a quarter-wave plate-based geometric phase lens (QWP GPL) and a polarization control unit of the present invention can be applied to all optical designs in the form of AR / VR / MR HMD.

[0022] An optical device according to an embodiment of the present invention can be utilized as a focus and depth variable lens module to resolve a vergence-accommodation conflict problem that may occur in an AR / VR / MR HMD device.

[0023] Since the optical device according to an embodiment of the present invention can implement three focus and depth variations with a single QWP GPL optical module, it can implement 3^n focus and depth variations through a stack structure of n sheets. This can provide more depth variation stages with the introduction of fewer modules than the existing HWP GPL stack structure.

[0024] Figure 1 is a conceptual diagram illustrating an optical module according to an embodiment of the present invention.

[0025] Figure 2 is a conceptual diagram for explaining the operating principle of a phase lens unit according to an embodiment of the present invention.

[0026] Figure 3 illustrates the operation of an optical module according to an embodiment of the present invention.

[0027] Figure 4 illustrates the operation of a polarization selection unit of an optical module according to an embodiment of the present invention.

[0028] FIG. 5 illustrates an optical device including a plurality of optical modules according to an embodiment of the present invention.

[0029] Figure 6 illustrates an augmented reality device according to an embodiment of the present invention.

[0030] Hereinafter, the details of the present invention will be described.

[0031] The embodiments described below are merely examples of the present invention, and the present invention can be modified in various forms. Accordingly, the specific configurations and functions disclosed below do not limit the scope of the claims.

[0032] The present invention proposes an optical module capable of generating three different wavefront modulation effects with a single optical module. The detailed operating principles and application examples of the polarization conversion element and QWP GPL included in the module are described in the following sections.

[0033] Figure 1 is a conceptual diagram showing an optical module (100) according to an embodiment of the present invention.

[0034] Referring to FIG. 1, the optical module (100) of the present invention may include a polarization control unit (120), a phase lens unit (130), and a polarization selection unit (140).

[0035] According to an embodiment of the present invention, a polarization control optic can control the polarization state of light before light is incident on a phase lens unit.

[0036] Specifically, the polarization control unit (120) may include a 1 / 4 wavelength plate and a switchable half-wave plate (HWP, Half-Wave Plate).

[0037] At this time, a quarter-wave plate (QWP) can be used to change the phase of polarized light.

[0038] Additionally, QWPs can be made of anisotropic materials with two axes of different refractive indices (typically a fast axis and a slow axis). The QWPs are manufactured to a specific thickness so that incident light propagates along the two axes with a phase difference of 90 degrees (λ / 4, or 1 / 4 wavelength).

[0039] The phase lens unit (130) according to an embodiment of the present invention can perform a role of changing the polarization state of incident light, and can include a quarter-wave plate-based geometric phase lens (QWP GPL, Quarter-Wave Plate Geometric Phase Lens).

[0040] A polarization selection optic according to an embodiment of the present invention can selectively transmit light passing through a phase lens unit, thereby allowing only light of a desired polarization state to pass through.

[0041] The above polarization selection unit may include a quarter-wave plate, a switchable half-wave plate (HWP, Half-Wave Plate), and a linear polarizing plate.

[0042] At this time, the switchable half-wave plate (Switchable HWP) can switch the polarization direction of circularly polarized light incident on the lens between right circular polarization and left circular polarization depending on the on / off state.

[0043] Meanwhile, the optical module (100) according to an embodiment of the present invention may also be combined with a linear polarizer (110) to form an optical device or optical system.

[0044] At this time, the linear polarizing unit (110) may be a linear polarizing plate. Light passing through the linear polarizing plate may be in a linear polarization state in which the electric field vibrates only in a specific direction.

[0045] The operating principle of the above 1 / 4 wave plate-based geometric phase lens (QWP GPL) is described in Fig. 2.

[0046] Figure 2 is a conceptual diagram for explaining the operating principle of a phase lens unit according to an embodiment of the present invention.

[0047] According to an embodiment of the present invention, the phase lens unit may include a quarter-wave plate-based geometric phase lens (QWP GPL, Quarter-Wave Plate Geometric Phase Lens).

[0048] The above-mentioned phase lens unit can be designed and manufactured under the condition that the thickness of the optical medium layer is a 1 / 4 wavelength plate. Accordingly, based on the polarization direction of circularly polarized light incident on the phase lens unit (left-hand circular polarization, right-hand circular polarization), the wavefront modulation function of the phase lens unit can simultaneously generate two wavefronts in one circularly polarized state.

[0049] Specifically, the two wavefronts can be varied by combining a concave lens (-f) and a transmission mode or by combining a convex lens (+f) and a transmission mode.

[0050] For example, referring to FIG. 2, when the left-circular polarization (LCP) that rotates counterclockwise by the quarter-wave plate is incident on the polarization-dependent lens, the polarization-dependent lens can be a lens with a negative focal length.

[0051] Alternatively, when the polarization-dependent lens is incident with the right-circular polarization (RCP) that rotates clockwise by the 1 / 4 wave plate, the polarization-dependent lens can be a lens with a positive focal length.

[0052] Additionally, at the same time, some light can pass through the phase lens section in transmission mode without any deformation.

[0053] Hereinafter, a multi-stage depth variable optical device using an optical module according to an embodiment of the present invention will be described.

[0054] FIG. 3 is a drawing showing an optical device using a 1 / 4 wave plate-based geometric phase lens (QWP GPL) according to an embodiment of the present invention.

[0055] According to an embodiment of the present invention, light generated from a display or a light source can pass through a linear polarizing unit (310). The linear polarizing unit (310) can linearly polarize the light generated from the display or the light source.

[0056] Thereafter, the linearly polarized light sequentially passes through the polarization control unit (320), the phase lens unit (330), and the polarization selection unit (340), thereby implementing a multi-stage depth-variable optical system.

[0057] According to an embodiment of the present invention, the switchable half-wave plate of the polarization control unit can modulate the polarization direction of circularly polarized light incident on the phase lens unit to right circular polarization or left circular polarization based on the driving state.

[0058] Specifically, when a polarization control unit is placed before the incident light of the phase lens unit (330), the polarization direction of circularly polarized light incident on the phase lens unit (330) can be selected between right-handed circular polarization and left-handed circular polarization based on the operating state (field-on, field-off) of the switchable half-wave plate (switchable HWP).

[0059] According to an embodiment of the present invention, the phase lens unit (330) can be selectively implemented in two modes: a combination of a concave lens (-f) and a transmission mode, or a combination of a convex lens (+f) and a transmission mode. Examples of the two modes overlap with the embodiment of FIG. 2, and are therefore omitted.

[0060] Meanwhile, since light emitted from the phase lens unit simultaneously generates two output wavefronts for a single incident circular polarization state, the additional design and introduction of a circular polarization filter is required to ensure that only one wavefront is emitted. This necessitates an additional polarization selection unit.

[0061] Figure 4 shows the degree of polarization of light that changes as it is equipped in a polarization selection unit according to an embodiment of the present invention.

[0062] Referring to FIG. 4, the light passing through the output portion of the phase lens unit (330, QWP GPL) can be arranged to pass through a polarization selection optic.

[0063] Accordingly, the linear polarizing unit, polarization control unit, phase lens unit, and polarization selection unit can be designed to be stacked side by side, and among these, the polarization control unit, phase lens unit, and polarization selection unit can form an optical module.

[0064] According to an embodiment of the present invention, the polarization selection unit can selectively filter one of two wavefronts emitted from the phase lens unit based on the operating state (field-on, field-off) of a switchable half-wave plate (switchable HWP).

[0065] Specifically, in the case of an emission wavefront in which wavefront modulation occurs, the polarization state of the emission wavefront can be switched to a polarization state orthogonal to the incident polarization state.

[0066] On the other hand, in the case of the transmission mode where no wavefront modulation occurs, the polarization state of the transmission mode can be maintained the same as the incident polarization.

[0067] The above polarization selection unit can function as a dynamic circular polarization filter by having two output wavefronts that are orthogonal in polarization state and by allowing light passing through a quarter-wave plate and a switchable half-wave plate (switchable HWP) to pass through a linear polarization unit, and can selectively filter two wavefronts.

[0068] Meanwhile, it is also possible to configure an optical device or an optical system by stacking a plurality of optical modules according to an embodiment of the present invention, and the stacked optical modules can be used in combination with a linear polarizer.

[0069] An optical device or optical system in which multiple optical modules are stacked is described in FIG. 5.

[0070] FIG. 5 is a drawing showing an optical device in which a plurality of optical modules are stacked according to an embodiment of the present invention.

[0071] An optical device according to an embodiment of the present invention may include at least one optical module.

[0072] As described above, each of the at least one optical module may include a polarization control unit, a phase lens unit, and a polarization selection unit.

[0073] Referring to FIG. 5, the optical system represents an optical system in which a linear polarizing unit and N optical modules arranged after the linear polarizing unit are stacked.

[0074] According to an embodiment of the present invention, the nth optical module (5n0) can measure the nth phase lens unit, the nth polarization control unit, and the nth polarization selection unit.

[0075] As described above, each of the nth polarization control units may include a switchable half-wave plate (HWP) and a quarter-wave plate.

[0076] Additionally, the nth polarization selection optic may have a structure in which a quarter-wave plate, a switchable half-wave plate, and a linear polarizer are sequentially stacked.

[0077] An optical device according to an embodiment of the present invention may be capable of generating 3 to the nth power of different focal planes when n sheets are stacked by having n stacked optical modules.

[0078] In addition, since polarization filtering can be implemented in the polarization selection unit compared to the conventional half-wave plate-based geometric phase lens (HWP GPL) module, light having a circular polarization state orthogonal to the intended polarization can be filtered.

[0079] This can have the effect of reducing the occurrence of ghost images in AR and VR optical systems.

[0080] This will enable us to implement features that can improve the quality of the video provided to users.

[0081] FIG. 6 is a conceptual diagram illustrating an augmented reality (AR) device using an optical system according to an embodiment of the present invention.

[0082] Referring to FIG. 6, an augmented reality (AR) device (600) according to an embodiment of the present invention may include an optical device configured with a stacked structure of optical modules (QWP GPL MODULE, Quarter-Wave Plate Geometric Phase Lens module) that provide a multi-stage depth variable function.

[0083] According to an embodiment of the present invention, an augmented reality device (600) may include an optical system in which a display, a passive lens, a linear polarizer, a mirror, a beam splitter, and at least one optical module are stacked.

[0084] Specifically, the display may include Organic Light Emitting Diode on Silicon (OLEDOS) that generates virtual images in an augmented reality device.

[0085] Additionally, a passive lens may include a lens used to control and focus light.

[0086] Additionally, a linear polarizer allows only light of a specific polarization direction to pass through, allowing subsequent polarization control.

[0087] Additionally, a beam splitter is an optical device that reflects or transmits incident light and distributes it into multiple paths, thereby transmitting the image generated on the display to the user's eyes.

[0088] Additionally, the mirror can reflect light that has passed through the beam splitter and ultimately enter the user's eye.

[0089] Additionally, the optical system in which multiple optical modules are stacked is the same as previously described.

[0090] According to an embodiment of the present invention, the augmented reality device allows an image output from a display to pass through a passive lens and an optical system to reach a beam splitter.

[0091] In an embodiment, light passing through the beam splitter may be reflected by a mirror and then re-entered through the beam splitter into the user's eye.

[0092] An optical system according to an embodiment of the present invention can vary the virtual depth of a virtual image based on whether a polarization control unit laminated on a QWP GPL optical module is operated.

[0093] That is, each QWP GPL optical module can be implemented in one of the concave lens, transmission mode, and convex lens mode, so that when n modules are stacked, a total of 3 to the nth power of focal plane depth variations can be controlled.

[0094] For example, in the case of an optical system including a first QWP GPL module and a second QWP GPL module, a total of nine depth variable planes can be implemented, so that the position of the virtual image depth plane can be designed.

[0095] Accordingly, it will be possible to introduce a depth plane recognition function based on convergence that takes into account the user's eyes, which is a characteristic of human vision that was not considered in existing binocular disparity images.

[0096] For example, considering the depth information (depth of field) of the human eye, if the position of each virtual image depth plane is designed to be able to switch within the comfort zone of the 0.3D condition in the depth range from the closest distance that a human can perceive (e.g., 20 cm) to infinity, the nine depth variable planes of the optical system will be able to satisfy the 0.3D comfort zone condition by sequentially switching the virtual image depth planes for the depth planes from the closest distance (20 cm) to infinity.

[0097] The present invention can be utilized as a focus and depth variable lens module to resolve the vergence-accommodation conflict problem that may occur in AR / VR / MR devices by using the above augmented reality device.

[0098] In addition, since the present invention can implement three focus and depth variations with a single QWP GPL optical module, it can implement 3n focus and depth variations through an n-sheet stack structure, which can provide more depth variation steps with the introduction of fewer modules than the existing HWP GPL stack structure.

[0099] For example, two QWP GPL laminated structure optical modules can selectively switch virtual images on nine different depth planes, and when considering human accommodation conditions, the depth planes can be arranged step by step from 20 cm to infinity from the eye, and the optical module can express all of the corresponding depths even under comfort zone conditions of 0.3D or less.

[0100] This reduces the number of GPLs compared to when conventional HWP GPL modules are used (2^n focal planes can be varied through n module stacks), which improves the quality of virtual images, and also reduces the number of stack modules, enabling the implementation of a lighter and thinner optical system.

[0101] In addition, the present invention can be applied to all AR / VR / MR devices that provide focus and depth variation, such as waveguide-type AR / VR optical systems, AR / VR optical systems utilizing pancake lenses, and free-path type AR / VR optical systems, in addition to the optical systems of augmented reality devices.

[0102] While the above description focuses on services and embodiments, these are merely examples and do not limit the present invention. Those skilled in the art will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the services and embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, differences related to such modifications and applications should be construed as being included within the scope of the present invention as defined in the appended claims.

Claims

1. Polarization control unit that controls the polarization state of light; A phase lens unit that changes the polarization state of light emitted from the polarization control unit; and Including a polarization selection unit that selectively transmits light passing through the above-mentioned phase lens unit, Optical devices.

2. In paragraph 1, It further includes a linear polarizing unit that linearly polarizes the light output from the light source, The light emitted from the linear polarizing section is incident on the polarization control section. Optical devices.

3. In paragraph 1, The above polarization control unit, Modulating the incident linear polarization into circular polarization of left-handed circular polarization rotating counterclockwise or right-handed circular polarization rotating clockwise. Optical devices.

4. In paragraph 1, The above polarization control unit includes a 1 / 4 wave plate and a switchable half-wave plate. Optical devices.

5. In paragraph 4, The above switchable half-wave plate modulates the polarization direction of circularly polarized light incident on the phase lens unit to right circular polarization or left circular polarization based on the driving state. Optical devices.

6. In paragraph 1 The above phase lens part, Including a quarter-wave plate-based geometric phase lens (QWP GPL, Quarter-Wave Plate Geometric Phase Lens), Optical devices.

7. In paragraph 1, The above polarization selection unit, Including a 1 / 4 wave plate, a switchable half-wave plate (HWP) and a linear polarizer. Optical devices.

8. In paragraph 1, The above polarization selection unit Selectively filtering one of the two wavefronts emitted from the phase lens unit based on the operating state (field-on, field-off) of the switchable half-wave plate (switchable HWP). Optical devices.

9. In paragraph 1, The optical device comprises a plurality of optical modules, Each of the above plurality of optical modules, A polarization control unit that controls the polarization state of light; A phase lens unit that changes the polarization state of light emitted from the polarization control unit; and A polarization selection unit that selectively transmits light passing through the above-mentioned phase lens unit; Optical devices.

10. In the method of operating an optical device, A step in which a polarization control unit adjusts the polarization state of light; A step in which the phase lens unit changes the polarization state of light emitted from the polarization control unit; and A polarization selection unit includes a step of selectively transmitting light passing through the phase lens unit. Method of operation of an optical device.

11. In paragraph 10, A step in which a linear polarizing unit linearly polarizes light output from a light source; and Further comprising a step of causing light emitted from the linear polarizing unit to enter the polarization control unit. Method of operation of an optical device.

12. In paragraph 10, The step of the above polarization control unit adjusting the polarization state of light is: A step of modulating the incident linear polarization into a circular polarization of left-handed circular polarization rotating counterclockwise or right-handed circular polarization rotating clockwise, Method of operation of an optical device.

13. In paragraph 10, The above polarization control unit includes a 1 / 4 wave plate and a switchable half-wave plate. Method of operation of an optical device.

14. In paragraph 13, The step in which the polarization control unit adjusts the polarization state of light is: A step of modulating the polarization direction of circularly polarized light incident on the phase lens unit to right circular polarization or left circular polarization based on the driving state of the switchable half-wave plate, Method of operation of an optical device.

15. In Article 10 The above phase lens part, Including a quarter-wave plate-based geometric phase lens (QWP GPL, Quarter-Wave Plate Geometric Phase Lens), Method of operation of an optical device.

16. In paragraph 10, The above polarization selection unit, Including a 1 / 4 wave plate, a switchable half-wave plate (HWP) and a linear polarizer. Method of operation of an optical device.

17. In paragraph 10, The step of selectively transmitting light that has passed through the phase lens unit by the polarization selection unit is as follows: A step of selectively filtering one of two wavefronts emitted from the phase lens unit based on the driving state (field-on, field-off) of a switchable half-wave plate (switchable HWP), Method of operation of an optical device.

18. In paragraph 10, The optical device comprises a plurality of optical modules, Each of the above plurality of optical modules, A polarization control unit that controls the polarization state of light; A phase lens unit that changes the polarization state of light emitted from the polarization control unit; and A polarization selection unit that selectively transmits light passing through the above-mentioned phase lens unit; Method of operation of an optical device.

19. A display that outputs light that forms an image; A polarization control unit that controls the polarization state of the light; A phase lens unit that changes the polarization state of light emitted from the polarization control unit; A polarization selection unit that selectively transmits light passing through the above-mentioned phase lens unit; and A beam splitter that reflects or transmits light passing through the polarization selection unit and provides the light to the user; Augmented reality device.

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