Optical system and apparatus using geometric phase lens

Abstract

The present invention relates to an optical system including a geometric phase lens, a quarter wave plate (QWP), and a mirror, wherein the quarter wave plate is positioned between the geometric phase lens and the mirror, and the geometric phase lens operates as a convex lens having a focal power of + f by converting light of a right circularly polarized component, which is incident on a front surface thereof, into light of a left circularly polarized component.

Description

Optical systems and devices using geometric phase lenses

[0001] The present invention relates to VR / AR / MR technology, and more particularly, to an HMD for implementing the same and an optical system built into the HMD.

[0002] In HMDs designed to implement VR / AR / MR, discrepancies between the depth information of the image 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 problem, known as the vergence-accomodation conflict (VAC), is a focus-variable optical system that can match the virtual image depth information to the distance perceived by the user as the focal plane.

[0003] Meanwhile, a conventional solution to VAC has been to vary the distance of the virtual image according to the change in the focal length of the optical system by physically moving the distance between the lenses within the optical system. However, this has the problem of increasing the volume and weight of the entire optical system because the volume of the optical system is designed to include the physical and mechanical movement of the lenses. This causes physical fatigue to the user when wearing the device. To address this, interest has been growing in optical devices based on geometric phase (GP), which can freely implement the wavefront profile characteristics that are spatially modulated in optical devices on a single-thickness thin film without changing the surface step of the optical device.

[0004] The purpose of the present invention is to provide an optical system using a GP lens and a quarter wave plate (QWP) to realize a more compact and simple optical system.

[0005] An optical system according to an embodiment of the present disclosure includes a geometric phase lens, a quarter wave plate (QWP), and a mirror, wherein the quarter wave plate can be positioned between the geometric phase lens and the mirror.

[0006] In addition, the geometric phase lens can operate as a convex lens having a focal power of +f by converting light of a right-circular polarization component incident on the front surface into light of a left-circular polarization component.

[0007] In addition, the light of the left-circular polarization component is converted into light of the linear polarization component through phase delay by the quarter-wave plate, and the light of the linear polarization component is converted into light of the left-circular polarization component while passing through the mirror and the quarter-wave plate again, and can be converted into light of the right-circular polarization component by being incident on the opposite surface of the geometric phase lens.

[0008] In addition, the geometric phase lens can operate as a convex lens having a focal power of -f by converting the left-circular polarization component of light incident on the front surface into the right-circular polarization component of light.

[0009] In addition, the light of the right-hand circular polarization component is converted into light of the linear polarization component through phase delay by the quarter-wave plate, and the light of the linear polarization component is converted into light of the right-hand circular polarization component while passing through the mirror and the quarter-wave plate again, and can be converted into light of the left-hand circular polarization component by being incident on the opposite surface of the geometric phase lens.

[0010] An optical system according to an embodiment of the present disclosure includes a Switchable HWP, a quarter wave plate (QWP), a mirror, a geometric phase lens, and a Switchable QWP, wherein the Switchable HWP, the quarter wave plate, the geometric phase lens, the Switchable QWP, and the mirror may be arranged in sequence.

[0011] In addition, when the Switchable HWP is in the ON state, the polarization component of the incident light is not converted and is converted into light of a left-circular polarization component by passing through the quarter-wave plate, and the light of the left-circular polarization component is converted into light of a right-circular polarization component by passing through the front surface of the geometric phase lens, and the light of the right-circular polarization component is converted from circular polarization to 90° linear polarization when the Switchable QWP is in the OFF state, and is reflected by a mirror to maintain 90° linear polarization.

[0012] In addition, when the Switchable HWP is controlled to ON, the polarization component of the incident light is not converted and is converted into light of a left-circular polarization component by passing through the quarter-wave plate, and the light of the left-circular polarization component is converted into light of a right-circular polarization component by passing through the front surface of the geometric phase lens, and when the Switchable QWP is in the ON state, the light of the right-circular polarization component can be transmitted without polarization modulation and reflected from the mirror to become light of a left-circular polarization component.

[0013] In addition, when the Switchable HWP is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right-circular polarization component by passing through the quarter-wave plate, and the light of the right-circular polarization component is converted into a left-circular polarization component by passing through the front surface of the geometric phase lens, and when the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation, and is reflected by the mirror and can be converted into light of a right-circular polarization component.

[0014] In addition, when the switchable HWP is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right-circular polarization component by passing through the quarter-wave plate, and the light of the right-circular polarization component is converted into a left-circular polarization component by passing through the front surface of the geometric phase lens, and when the switchable QWP is in the OFF state, the circular polarization is converted into 0° linear polarization, and is reflected by the mirror to maintain the 0° linear polarization.

[0015] An optical system according to an embodiment of the present disclosure includes a Switchable HWP, a quarter wave plate, a geometric phase lens, a Switchable QWP, and a concave mirror, wherein the Switchable HWP, the quarter wave plate, the geometric phase lens, the Switchable QWP, and the concave mirror can be arranged in sequence.

[0016] In addition, when the switchable HWP is in the ON state, the polarization component of the incident light passes through the quarter wave plate without being converted and is converted into light of a left-circular polarization component, the light of the left-circular polarization component is converted into light of a right-circular polarization component by passing through the front surface of the geometric phase lens, and the light of the right-circular polarization component is converted from circular polarization to 90° linear polarization when the switchable QWP is in the OFF state, and is reflected by the concave mirror to maintain 90° linear polarization.

[0017] In addition, when the Switchable HWP is in the ON state, the polarization component of the incident light passes through the quarter wave plate without being converted and is converted into light of a left-circular polarization component, and the light of the left-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of a right-circular polarization component, and when the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation and can be reflected by the concave mirror and converted into light of a left-circular polarization component.

[0018] In addition, when the Switchable HWP is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component and is converted into light of a right-circular polarization component by passing through the QWP, and the light of the right-circular polarization component is converted into light of a left-circular polarization component by passing through the front surface of the geometric phase lens, and when the Switchable QWP is in the ON state, the light of the left-circular polarization component can be transmitted without polarization modulation and reflected by the concave mirror to be converted into light of a right-circular polarization component.

[0019] In addition, when the Switchable HWP is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right-circular polarization component by passing through the quarter-wave plate, and the light of the right-circular polarization component is converted into light of a left-circular polarization component by passing through the front surface of the geometric phase lens, and when the Switchable QWP is in the OFF state, the light of the left-circular polarization component is converted from circular polarization to 0° linear polarization, and the image is reflected on a concave mirror to maintain 0° linear polarization.

[0020] An HMD according to an embodiment of the present disclosure may have an optical system having the above-described characteristics.

[0021] According to an embodiment of the present invention, by using a GP lens, the phase of a light wave passing through a geometric phase holographic lens can be controlled, thereby allowing for precise design and manufacture of any wavefront profile required in an optical device by means of a spatial geometric phase distribution of a phase delay optical axis.

[0022] Additionally, it is possible to implement optical elements in the form of flat optics that are much lighter and thinner than conventional refractive lenses.

[0023] Figure 1 illustrates a conventional optical system according to an embodiment of the present invention.

[0024] FIG. 2 illustrates an optical system including a geometric phase lens according to an embodiment of the present invention.

[0025] FIG. 3 illustrates an optical system using a geometric phase lens and a quarter wave plate according to an embodiment of the present invention.

[0026] Figures 4 to 11 illustrate examples of implementation of an optical system using a geometric phase lens and a quarter wave plate according to an embodiment of the present invention.

[0027] Hereinafter, the details of the present invention will be described.

[0028] 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.

[0029] Figure 1 illustrates an example of a round trip optical system according to an embodiment of the present invention.

[0030] Figure 1 is a traditional optical system that amplifies refractive power by installing a general convex lens on a round-trip optical path.

[0031] Referring to Figure 1, in the optical system, light is refracted once when it enters a convex lens, and when it hits a mirror and returns, it is refracted once more through the convex lens. Such an optical system is used to provide greater refractive power through a lens with limited refractive power.

[0032] This enables high-angle images to be realized with low-magnification lenses in VR / AR / MR HMDs. However, typical refractive convex lenses have limitations in terms of weight and size from the perspective of the HMD's form factor. Below, we propose a method to replace the above-mentioned convex lens with a geometric phase lens.

[0033] FIG. 2 illustrates an optical system including a geometric phase lens according to an embodiment of the present invention.

[0034] Referring to FIG. 2, a conventional variable focus AR optical system (FIG. 2(a)) utilizing a geometric phase lens (GP lens) can express a virtual image plane having two different depth information by two lens modes (+f, -f) based on the state of incident circular polarization (right-hand circular polarization (RCP), left-hand circular polarization (LCP)) to the geometric phase lens (GP lens).

[0035] In addition, Fig. 2(b) can be designed so that the light passes through the geometric phase lens (GP lens) twice on the optical path by positioning the geometric phase lens (GP lens) between the beam-splitter (BS) and the mirror surface.

[0036] In the above optical system, when light with a right-circular polarization (RCP) component is incident on the front surface of a geometric phase lens (GP lens), the polarization state of the light is converted to a left-circular polarization (LCP) component, which causes the GP lens to operate as a convex lens with a focal power of +f. Thereafter, the left-circular polarization component of light is reflected by a mirror, the optical path is reversed, and the light is converted to a right-circular polarization component.

[0037] Afterwards, the light with the right-circular polarization component is incident on the back of the geometric phase lens (GP lens), and the GP lens operates as a concave lens with a focal power of -f, which can cause the focal power of the entire optical system to be canceled out. In other words, when looking at the entire optical system, the effect is the same as if there is no lens.

[0038] Meanwhile, the RCP (Right Circular Polarization) and LCP (Left Circular Polarization) represent two types of circular polarization, which represent a polarization state in which the electric field of light or other electromagnetic waves rotates in a specific direction.

[0039] FIG. 3 illustrates an optical system in which a quarter-waveplate (QWP) is positioned between a geometric phase lens (GP lens) and a mirror according to an embodiment of the present invention.

[0040] According to an embodiment of the present invention, a quarter-waveplate (hereinafter, QWP) is a type of polarizing filter used in optics, and is used to convert the polarization state of light. The QWP is made of a double-refractive material of a specific thickness and is designed to delay the phase of passing light by 90 degrees, or 1 / 4 of a wavelength.

[0041] In addition, a switchable quarter-waveplate is a QWP designed to control polarization change by changing the bi-refractive property by electrical, thermal, or mechanical means as needed, and may mean an optical element that can control the polarization state by changing the polarization direction of light.

[0042] Referring to Fig. 3, by positioning a quarter-waveplate (QWP) between a geometric phase lens (GP lens) and a mirror, light with a right-circular polarization component incident on the front surface of the geometric phase lens (GP lens) is converted into light with a left-circular polarization component, and operates as a convex lens with a focal power of +f.

[0043] Afterwards, it is converted into linearly polarized light through phase delay by QWP.

[0044] The linearly polarized light passes through the mirror and QWP again, is converted into left-circularly polarized light, and is incident on the opposite surface of the geometric phase lens (GP lens), where it is converted into right-circularly polarized light, and once again functions as a convex lens with a focal power of +f.

[0045] That is, the focal power of the geometric phase lens (GP lens) in the entire optical system becomes +2f.

[0046] Conversely, it can be understood by the same principle that when the circularly polarized light initially incident on the geometric phase lens (GP lens) is changed to a left-hand circularly polarized light component according to various embodiments, the focal length of the entire optical system appears as -2f.

[0047] Based on the above embodiment, a single geometric phase lens (GP lens) can generate twice the focal power, which can be obtained by utilizing a relatively long focal lens instead of a single focal lens that requires a high-resolution optical recording pattern, and at the same time, a virtual image plane with a wide field of view can be obtained by applying the single focal lens to a focus-variable AR optical system.

[0048] Hereinafter, various embodiments according to the present invention will be further described.

[0049] Figures 4 to 7 sequentially illustrate a method of controlling the focal length of the entire optical system by controlling the incident polarization to a geometric phase lens (GP lens) using a switchable half-waveplate (HWP) and a switchable QWP.

[0050] First, a switchable half-waveplate (HWP) is an HWP designed to control polarization change by changing the bi-refractive properties by electrical, thermal, or mechanical means as needed. An HWP can mean an optical element that can control the polarization state by changing the polarization direction of light by rotating the electric field vector of light by 90 degrees.

[0051] An optical system according to an embodiment of the present invention may include a switchable half-waveplate (HWP), a QWP, a switchable QWP, and a geometric phase lens.

[0052] Figure 4 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) generates a lens effect of -f, -f.

[0053] According to an embodiment of the present invention, light emitted from a micro-display is refracted at a specific angle by a passive convex lens and enters the optical system.

[0054] The incident light passes through a linear polarizer (LP) and can be converted into light with a 0° linear polarization component. The converted light is incident on a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0055] The above switchable HWP can perform a role of converting the polarization state of incident light into an output polarization component orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0056] For example, when voltage is applied to the Switchable HWP and it is in the ON state, the polarization component of the incident light passes through without being converted and can be converted into light with a left-circular polarization component after passing through the QWP. Afterwards, it passes through the front surface of the geometric phase lens (GP lens) and is converted into a right-circular polarization component, and passes through the geometric phase lens (GP lens) operating in the lens mode with a focal power of -f.

[0057] According to an embodiment, light passing through a geometric phase lens passes through a switchable QWP that can transmit the polarization state of the incident light without polarization modulation or delay it under quarter-waveplate conditions depending on whether a voltage is applied thereafter.

[0058] As shown in Fig. 4, when the Switchable QWP is OFF, the light is converted from circular polarization to 90° linear polarization, and maintains 90° linear polarization even when reflected from the mirror. In other words, the light passes through the Switchable QWP and becomes RCP. The light converted to RCP passes through the back of the geometric phase lens (GP lens) and once again has a focal length of -f, so that the entire optical system has an additional focal length of -2f through the geometric phase lens (GP lens).

[0059] Figure 5 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) generates a lens effect of -f and +f.

[0060] Referring to Fig. 5, as with the description of Fig. 4, light emitted from the micro-display enters the optical system at a specific angle through a passive convex lens. The incident light passes through a linear polarizer (LP), and the light converted into light with a 0° linear polarization component enters a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0061] The above switchable HWP can change the polarization state of incident light to a component of outgoing polarization orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0062] When voltage is applied to the Switchable HWP and it is in the ON state, the polarization component of the incident light passes through without being converted, passes through the QWP, and is converted into light with a left-hand circular polarization component. Afterwards, it passes through the front surface of the geometric phase lens (GP lens) and is converted into a right-hand circular polarization component, and passes through the geometric phase lens (GP lens) which operates in lens mode with a focal power of -f.

[0063] Light passing through the geometric phase lens then passes through a switchable QWP, which can transmit the polarization state of the incident light without polarization modulation or delay it under quarter-waveplate conditions, depending on whether a voltage is applied.

[0064] According to an embodiment of the present invention, when the Switchable QWP is in the ON state as shown in FIG. 5, light transmits the polarization state without polarization modulation and is reflected by the mirror to become the LCP. Thereafter, the light passes through the Switchable QWP again without polarization modulation, and the LCP passes through the back of the geometric phase lens (GP lens) to have a focal length of +f, so that the entire optical system can sequentially add the focal lengths of -f and +f through the geometric phase lens (GP lens).

[0065] Figure 6 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) generates +f and -f lens effects.

[0066] Referring to Fig. 6, light emitted from a microdisplay enters the optical system at a specific angle through a passive convex lens. The light, which passes through a linear polarizer (LP) and is converted into light with a 0° linear polarization component, enters a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0067] The above switchable HWP can perform a role of converting the polarization state of incident light into an output polarization component orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0068] According to Fig. 6, when voltage is applied to the Switchable HWP and it is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component and passes through the QWP to be converted into light of a right-circular polarization component.

[0069] Afterwards, the light with the right-circular polarization component passes through the front surface of the geometric phase lens (GP lens) and is converted into the left-circular polarization component, passing through the geometric phase lens (GP lens) which operates in a lens mode with a focal power of +f.

[0070] Afterwards, depending on whether voltage is applied, the polarization state of the incident light passes through a switchable QWP that can transmit without polarization modulation or delay under quarter-waveplate conditions.

[0071] According to an embodiment of the present invention, when the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation, and is reflected by a mirror to become light of a right-circular polarization component (RCP). Afterwards, it passes through the Switchable QWP again, but is transmitted without polarization modulation, and the LCP passes through the back of the geometric phase lens (GP lens) and feels the focal length of +f, so that the entire optical system sequentially adds the focal lengths of +f and -f through the geometric phase lens (GP lens).

[0072] FIG. 7 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) according to an embodiment of the present invention generates a lens effect of +f and +f.

[0073] Referring to Fig. 7, light emitted from the micro-display enters the optical system at a specific angle through a passive convex lens.

[0074] The incident light passes through a linear polarizer (LP), and the light converted into light with a 0° linear polarization component is incident on a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0075] The above switchable HWP can change the polarization state of incident light to a component of outgoing polarization orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0076] According to an embodiment, when voltage is applied to the Switchable HWP and it is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component, and the converted light passes through the QWP and is converted into light of a right-circular polarization component.

[0077] Afterwards, the light with the right-circular polarization component passes through the front surface of the geometric phase lens (GP lens) and is converted into the left-circular polarization component, passing through the geometric phase lens (GP lens) which operates in a lens mode with a focal power of +f.

[0078] Afterwards, depending on whether voltage is applied, the polarization state of the incident light passes through a switchable QWP that can transmit without polarization modulation or delay under quarter-waveplate conditions.

[0079] In an embodiment, when the Switchable QWP is OFF, circular polarization is converted to 0° linear polarization, and when reflected from a mirror, the 0° linear polarization is maintained, and the light passes through the Switchable QWP and becomes an LCP. When the LCP passes through the back surface of the geometric phase lens (GP lens), it once again experiences a focal length of +f, so that the entire optical system gains a focal length of +2f through the geometric phase lens (GP lens).

[0080] As above, an optical system having various focal lengths was implemented through a geometric phase lens (GP lens) in FIGS. 4 to 7.

[0081] In the following, in FIGS. 8 to 11, an optical system is described in which the distance between the geometric phase lens (GP lens) and the concave mirror is not set to 0, and the mirror is a concave mirror having a focal length f.

[0082] FIG. 8 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) according to an embodiment of the present invention generates a lens effect of -f, -f.

[0083] Referring to Figure 8, light emitted from a microdisplay enters the optical system at a specific angle through a passive convex lens. The incident light passes through a linear polarizer (LP) and is converted into light with a 0° linear polarization component. The converted light is then incident on a switchable half-waveplate (HWP) made of liquid crystal cells.

[0084] The above switchable HWP can change the polarization state of incident light to a component of outgoing polarization orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0085] When the above Switchable HWP is ON, the polarization component of the incident light passes through without being converted, passes through the QWP, and is converted into light with a left-hand circular polarization component. The converted light then passes through the front surface of the geometric phase lens (GP lens), is converted into a right-hand circular polarization component, and passes through the geometric phase lens (GP lens) operating in lens mode with a focal power of -f.

[0086] Afterwards, depending on whether voltage is applied, the polarization state of the incident light passes through a switchable QWP that can transmit without polarization modulation or delay under quarter-waveplate conditions.

[0087] According to an embodiment of the present invention, light is converted from circular polarization to 90° linear polarization when the Switchable QWP is OFF, maintains 90° linear polarization even when reflected from a concave mirror, and becomes RCP after passing through the Switchable QWP. The RCP passes through the back surface of the geometric phase lens (GP lens) and once again experiences a focal length of -f, so that the entire optical system gains a focal length of -2f through the geometric phase lens (GP lens).

[0088] FIG. 9 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) according to an embodiment of the present invention generates a lens effect of -f and +f.

[0089] Referring to Figure 9, light emitted from a microdisplay enters the optical system at a specific angle through a passive convex lens. The incident light passes through a linear polarizer (LP), and the light converted into light with a 0° linear polarization component enters a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0090] The above switchable HWP can change the polarization state of incident light to a component of outgoing polarization orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0091] When the above Switchable HWP is in the ON state, the polarization component of the incident light passes through without being converted and is converted into light with a left-circular polarization component through the QWP.

[0092] The converted light then passes through the front of the geometric phase lens (GP lens) and is converted into a right-circular polarization component, passing through the geometric phase lens (GP lens) which operates in a lens mode with a focal power of -f.

[0093] Afterwards, depending on whether voltage is applied, the polarization state of the incident light passes through a switchable QWP that can transmit without polarization modulation or delay under quarter-waveplate conditions.

[0094] According to an embodiment of the present invention, when the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation and is reflected by a concave mirror to become an LCP.

[0095] Afterwards, it passes through the switchable QWP again, but without polarization modulation. The LCP senses the +f focal length as it passes through the back of the geometric phase lens (GP lens), and the entire optical system sequentially adds the -f and +f focal lengths through the geometric phase lens (GP lens).

[0096] FIG. 10 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) according to an embodiment of the present invention generates +f and -f lens effects.

[0097] Referring to Fig. 10, light emitted from a microdisplay enters the optical system at a specific angle through a passive convex lens. The light, which passes through a linear polarizer (LP) and is converted into light with a 0° linear polarization component, enters a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0098] According to an embodiment, the switchable HWP can change the polarization state of incident light to an output polarization component orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0099] When the above Switchable HWP is OFF, the 0° linear polarization component is converted into a 90° linear polarization component and passes through the QWP to be converted into light with a right-circular polarization component.

[0100] Afterwards, it passes through the front of the geometric phase lens (GP lens) and is converted into a left-circular polarization component, and passes through the geometric phase lens (GP lens) which operates in lens mode with a focal power of +f.

[0101] Afterwards, depending on whether voltage is applied, the polarization state of the incident light passes through a switchable QWP that can transmit without polarization modulation or delay under quarter-waveplate conditions.

[0102] According to an embodiment of the present invention, when the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation and is reflected by the concave mirror to become RCP.

[0103] Afterwards, it passes through the Switchable QWP again, but without polarization modulation. The LCP passes through the back of the geometric phase lens (GP lens) and senses the focal length of +f, so the entire optical system sequentially adds the focal lengths of +f and -f through the geometric phase lens (GP lens).

[0104] FIG. 11 shows the lens mode and polarization degree inside the optical system when a geometric phase lens (GP lens) according to an embodiment of the present invention generates a lens effect of +f and +f.

[0105] Referring to Fig. 11, light emitted from a micro-display enters the optical system at a specific angle through a passive convex lens. The light, which passes through a linear polarizer (LP) and is converted into light with a 0° linear polarization component, enters a switchable half-waveplate (HWP) made of a liquid crystal cell.

[0106] According to an embodiment, the switchable HWP can change the polarization state of incident light to an output polarization component orthogonal to the incident polarization by transmitting the incident light without polarization modulation or delaying it under half-waveplate conditions, depending on whether a voltage is applied.

[0107] When the above Switchable HWP is OFF, the 0° linear polarization component is converted into a 90° linear polarization component and passes through the QWP to be converted into light with a right-circular polarization component.

[0108] Afterwards, it passes through the front of the geometric phase lens (GP lens) and is converted into a left-circular polarization component, and passes through the geometric phase lens (GP lens) which operates in lens mode with a +f focal power. Afterwards, it passes through a switchable QWP which can transmit the polarization state of the incident light without polarization modulation or delay it under quarter-waveplate conditions depending on the presence or absence of voltage applied.

[0109] When the above Switchable QWP is OFF, circular polarization is converted to 0° linear polarization, and even when reflected from a concave mirror, 0° linear polarization is maintained, passing through the Switchable QWP and becoming an LCP. As the LCP passes through the back of the geometric phase lens (GP lens), it once again experiences a focal length of +f, and the entire optical system gains a focal length of +2f through the geometric phase lens (GP lens).

[0110] As described above, the optical system according to the embodiment of the present invention can implement various focal lengths by using an optical system in which the distance between the geometric phase lens (GP lens) and the mirror is not set to 0, but the mirror is a concave mirror having a focal length f.

[0111] Meanwhile, according to an embodiment of the present invention, an AR / VR device using the optical system may be included, and specifically, a head-mounted device (HMD) equipped with the optical system may be implemented.

[0112] Furthermore, 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. Geometric phase lens; Quarter wave plate (QWP); and including mirrors; The above quarter wave plate, Located between the geometric phase lens and the mirror, Optical system.

2. In paragraph 1, The above geometric phase lens operates as a convex lens with a focal power of +f by converting the right-circular polarization component of light incident on the front surface into the left-circular polarization component of light. Optical system.

3. In paragraph 2, The light of the above left-hand circular polarization component is, It is converted into linearly polarized light through phase delay by the above quarter wave plate, The light of the above linear polarization component passes through the mirror and the quarter wave plate again and is converted into light of the left circular polarization component. Light that is incident on the opposite surface of the geometric phase lens and converted into a right-circularly polarized light component, Optical system.

4. In paragraph 1, The above geometric phase lens operates as a convex lens with a focal power of -f by converting the left-circularly polarized light incident on the front surface into the right-circularly polarized light. Optical system.

5. In paragraph 4, The light of the above circularly polarized component is, It is converted into linearly polarized light through phase delay by the above quarter wave plate, The light of the above linear polarization component passes through the mirror and the quarter wave plate again and is converted into light of the right circular polarization component. Light incident on the opposite side of the geometric phase lens is converted into a left-circularly polarized light component. Optical system. 6.Switchable HWP; Quarter Wave Plate (QWP); mirror; Geometric phase lenses and Includes Switchable QWP, The Switchable HWP, the quarter wave plate, the geometric phase lens, the Switchable QWP and the mirror are arranged in sequence. Optical system.

7. In paragraph 6, When the above Switchable HWP is ON, the polarization component of the incident light is not converted and is converted into light with a left-circular polarization component as it passes through the quarter-wave plate. The light of the above left-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of the right-circular polarization component. The light of the above circularly polarized component is, When the above Switchable QWP is OFF, the circular polarization is converted to 90° linear polarization, and is reflected from the mirror to maintain 90° linear polarization. Optical system.

8. In paragraph 6, When the above Switchable HWP is controlled to ON, the polarization component of the incident light is not converted and is converted into light with a left-circular polarization component as it passes through the quarter-wave plate. The light of the above left-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of the right-circular polarization component. The light of the above circularly polarized component is When the Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation and is reflected from the mirror to become light of the left-circular polarization component. Optical system.

9. In paragraph 6, When the above Switchable HWP is OFF, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right circular polarization component through the quarter wave plate. The light of the above right-circular polarization component passes through the front surface of the geometric phase lens and is converted into the left-circular polarization component. When the above Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation, and is reflected from the mirror and converted into light of the right-circular polarization component. Optical system.

10. In paragraph 6, When the switchable HWP is OFF, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right-circular polarization component through the quarter-wave plate. The light of the above right-circular polarization component passes through the front surface of the geometric phase lens and is converted into the left-circular polarization component, When the above Switchable QWP is OFF, the circular polarization is converted to 0° linear polarization, and is reflected from the mirror to maintain 0° linear polarization. Optical system. 11.Switchable HWP; quarter wave plate; geometric phase lens; Switchable QWP and Includes a concave mirror, The Switchable HWP, the quarter wave plate, the geometric phase lens, the Switchable QWP and the concave mirror are arranged in sequence. Optical system.

12. In paragraph 11, When the switchable HWP is ON, the polarization component of the incident light passes through the quarter wave plate without being converted and is converted into light with a left-circular polarization component. The light of the above left-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of the right-circular polarization component. The light of the above circularly polarized component is converted from circularly polarized light to 90° linearly polarized light when the Switchable QWP is in the OFF state, and is reflected from the concave mirror to maintain 90° linearly polarized light. Optical system.

13. In paragraph 11, When the above Switchable HWP is in the ON state, the polarization component of the incident light passes through without being converted and is converted into light with a left-circular polarization component after passing through the quarter-wave plate. The light of the above left-circular polarization component passes through the front surface of the geometric phase lens and is converted into the right-circular polarization component, When the above Switchable QWP is in the ON state, the polarization state is transmitted without polarization modulation, and is reflected by the concave mirror and converted into light of the left circular polarization component. Optical system.

14. In paragraph 11, When the above Switchable HWP is OFF, the 0° linear polarization component is converted into a 90° linear polarization component and passes through the QWP to be converted into light with a right-circular polarization component. The light of the above right-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of the left-circular polarization component. When the above Switchable QWP is in the ON state, the light of the left-circular polarization component is transmitted without polarization modulation and is reflected by the concave mirror and converted into light of the right-circular polarization component. Optical system.

15. In paragraph 11, When the above Switchable HWP is in the OFF state, the 0° linear polarization component is converted into a 90° linear polarization component, and is converted into light of a right circular polarization component through the quarter wave plate. The light of the above right-circular polarization component passes through the front surface of the geometric phase lens and is converted into light of the left-circular polarization component. When the above Switchable QWP is OFF, the light of the left circular polarization component is converted from circular polarization to 0° linear polarization, and the image is reflected on the concave mirror to maintain 0° linear polarization. Optical system.

16. An HMD having an optical system according to any one of claims 1 to 15.

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