CN217821110U - Augmented reality system and display device comprising same - Google Patents
Augmented reality system and display device comprising same Download PDFInfo
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- CN217821110U CN217821110U CN202222071218.9U CN202222071218U CN217821110U CN 217821110 U CN217821110 U CN 217821110U CN 202222071218 U CN202222071218 U CN 202222071218U CN 217821110 U CN217821110 U CN 217821110U
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Abstract
The present disclosure provides an augmented reality system and a display apparatus including the same. The system according to the present disclosure comprises: a laser light source; a spatial light modulator configured to wavefront-modulate a laser beam from a laser light source to generate a modulated beam having depth information; a relay configured to form an optical path to relay the modulated light beam; a combiner configured to combine the modulated light beam from the relay with ambient light; and a speckle suppressor configured to suppress laser speckle by suppressing temporal coherence and/or spatial coherence of the laser beam or the modulated beam, wherein the speckle suppressor is used in combination with at least one of the laser light source, the spatial light modulator, and the repeater. The system and the display device according to the present disclosure can suppress speckles in a laser beam using a speckle suppressor, thereby improving the sharpness of the edges of an image and the integrity of the image and improving the display resolution.
Description
Technical Field
The present disclosure relates to the field of image display technologies, and in particular, to an augmented reality system capable of suppressing laser speckle and a display device including the same.
Background
Augmented Reality (AR) technology is a display technology that skillfully integrates virtual information with the real world. Holographic AR glasses are an important application of AR technology. Currently, holographic AR glasses project a holographic image through a laser light source, a spatial light modulator, and a mirror group, where the projection scheme may be selected from, for example, laser projection + Digital Micromirror Device (DMD), blue laser projection + fluorescent turntable + DMD, narrow-band LED + DMD, and the like.
However, the above projection schemes all generate the inherent phenomenon of "laser speckle", that is, when laser is diffusely reflected at the rough surface of the scattering body or passes through the transparent scattering body, randomly distributed bright and dark spots can be observed at or near the rough scattering surface, which results in the AR glasses appearing as "noise" at the edge of the image. The occurrence of laser speckle causes the defects of image edge blurring, partial image information missing and further display resolution reduction and the like.
SUMMERY OF THE UTILITY MODEL
The present disclosure provides an Augmented Reality (AR) system capable of suppressing laser speckle and a display device including the same. According to the method and the device, the phenomenon of laser speckle can be inhibited by adding the speckle inhibitor into the AR system, so that the definition of the edge of the image and the integrity of the image are improved, and the display resolution is improved.
According to an aspect of the present disclosure, there is provided an AR system including: a laser light source; a spatial light modulator configured to wavefront-modulate a laser beam from a laser light source to generate a modulated beam having depth information; a relay configured to form an optical path to relay the modulated light beam; a combiner configured to combine the modulated light beam from the relay with ambient light; and a speckle suppressor configured to suppress laser speckle by suppressing temporal coherence and/or spatial coherence of the laser beam or the modulated beam, wherein the speckle suppressor is used in combination with at least one of the laser light source, the spatial light modulator, and the repeater.
According to an embodiment of the present disclosure, the speckle suppressor is configured to satisfy the following relation:
wherein epsilon is the target degree of laser speckle contrast reduction, tau is the human eye response time, and t is the time required for updating the speckle pattern.
According to an embodiment of the present disclosure, the speckle suppressor includes a phase adjuster configured to suppress laser speckle by performing phase adjustment to suppress spatial coherence of the laser beam or the modulated beam.
According to an embodiment of the present disclosure, the phase adjuster is constituted by a fixed phase superlens, the speckle suppressor further comprising an actuator configured to rotate the fixed phase superlens with respect to an optical axis of the laser beam or the modulated beam, the rotation satisfying the following relation:
wherein epsilon is the target degree of laser speckle contrast reduction, tau is the human eye response time, and omega 0 To update the radian of rotation required for the speckle pattern, ω is the angular frequency of rotation.
According to an embodiment of the present disclosure, the phase adjuster is constituted by a fixed phase superlens, the speckle suppressor further comprising an actuator configured to oscillate the fixed phase superlens with respect to an optical axis of the laser beam or the modulated beam, the oscillation satisfying the following relation:
wherein epsilon is the target degree of laser speckle contrast reduction, tau is the human eye response time, f is the oscillation frequency, D is the diameter of the phase adjuster, and D is the oscillation displacement required for updating the speckle pattern.
According to an embodiment of the present disclosure, the phase adjuster is constituted by a phase-adjustable superlens configured to adjust a phase distribution of the superlens by changing a voltage applied thereto, and satisfies the following relational expression:
wherein epsilon is the target degree of the reduced laser speckle contrast, tau is the human eye response time, and t is the time required for updating the speckle pattern.
According to the embodiment of the disclosure, the phase-adjustable superlens is an electrically-controlled adjustable superlens, an optically-controlled adjustable superlens or a mechanically-controlled adjustable superlens.
According to an embodiment of the present disclosure, a superlens includes a substrate and a plurality of structural units arranged in an array disposed on a surface of the substrate, a nanostructure being disposed at a center position and/or a vertex position of each of the plurality of structural units.
According to the embodiment of the present disclosure, the planar shape of each of the plurality of structural units is a regular hexagon or a square.
According to an embodiment of the present disclosure, a speckle suppressor includes a wavelength adjuster used in combination with a laser light source, configured to suppress laser speckle by performing wavelength adjustment to suppress temporal coherence of a laser light beam.
According to the embodiment of the present disclosure, the number of the laser light sources is greater than or equal to two, and the number of the wavelength adjusters is the same as the number of the laser light sources and corresponds to the respective laser light sources, respectively.
According to an embodiment of the present disclosure, the laser light source is a wavelength tunable laser.
According to an embodiment of the present disclosure, the spatial light modulator includes a phase-tunable superlens serving as a speckle suppressor configured to adjust a phase distribution by changing a voltage applied thereto while wavefront-modulating a laser beam to generate a modulated beam.
According to an embodiment of the present disclosure, the repeater includes a 4f optical system, wherein a superlens serving as a speckle suppressor configured to filter out high frequency components in laser speckle is provided at a center between two lenses of the 4f optical system.
According to another aspect of the present disclosure, there is provided a display device comprising an augmented reality system according to the above aspect of the present disclosure.
According to the embodiment of the disclosure, the phase and/or the wavelength of the laser beam are changed to inhibit the spatial or temporal coherence of the laser, so that the speckle pattern can be updated in the response time of the human eye, the human eye can hardly perceive the existence of the speckle, and the purpose of inhibiting the speckle is achieved. Therefore, according to the embodiments of the present disclosure, by suppressing speckle, the definition of the edge of an image and the integrity of the image can be improved, thereby improving the display resolution.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.
Fig. 1 shows a schematic diagram of a configuration of an AR system according to an embodiment of the present disclosure;
fig. 2 shows a schematic diagram of an example of a speckle suppressor according to an embodiment of the present disclosure;
FIG. 3 shows a schematic plan view of the structural elements of a superlens used as a speckle suppressor;
FIG. 4 shows a graph of nanostructure diameter versus phase and transmission;
fig. 5 shows a schematic diagram of a configuration of an AR system according to a first embodiment of the present disclosure;
FIG. 6 shows a phase distribution diagram of a fixed-phase superlens used as a speckle suppressor included in an AR system according to a first embodiment of the present disclosure;
FIG. 7 shows a schematic diagram of speckle contrast for an AR system according to the prior art;
FIG. 8 shows a schematic diagram of speckle contrast of an AR system according to a first embodiment of the present disclosure;
fig. 9 shows a schematic diagram of a configuration of an AR system according to a second embodiment of the present disclosure;
fig. 10 shows a schematic diagram of a configuration of an AR system according to a third embodiment of the present disclosure;
fig. 11 shows a schematic diagram of a configuration of an AR system according to a fourth embodiment of the present disclosure; and
fig. 12 shows a schematic diagram of a configuration of an AR system according to a fifth embodiment of the present disclosure.
1: light source 2: spatial light modulator
3: the repeater 4: ambient light
31: first lens 32: second lens
5: the combiner 6: speckle suppressor
61: phase adjuster 61a: adjustable superlens
61b: fixed-phase superlens 62: wavelength regulator
7: laser beam with speckle 8: speckle free laser beam
9: the human eye 10: AR system
Detailed Description
The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly indicates otherwise.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is the same as a meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The high monochromaticity and high coherence of laser light causes scattering or transmission phenomena when the laser light is irradiated on a rough surface, resulting in irregular light intensity distribution and random speckle distribution, which is called a "laser speckle" phenomenon. In this regard, according to the concept of the present disclosure, the laser speckle phenomenon can be suppressed by suppressing coherence of laser light in time or space. Specifically, the speckle suppressor based on the super lens is used for suppressing the spatial or temporal coherence of laser by changing the phase of a laser beam in space or adjusting the laser wavelength in a certain range, so that speckle patterns with different phases or different wavelengths are updated in the response time of human eyes, the existence of speckles is difficult to be perceived by the human eyes, and the purpose of suppressing the speckles is achieved.
Fig. 1 shows a schematic diagram of a configuration of an AR system 10 according to an embodiment of the present disclosure. As shown in fig. 1, an AR system 10 according to an embodiment of the present disclosure may be a laser projection system. According to an embodiment of the present disclosure, as shown in fig. 1, an AR system 10 may include a laser Light source 1, a Spatial Light Modulator (SLM) 2, a relay 3, a combiner 5, and a speckle suppressor 6.
The laser light source 1 may also be referred to herein as light source 1. According to the embodiment of the present disclosure, the light source 1 may emit monochromatic laser light.
According to an embodiment of the present disclosure, as shown in fig. 1, the SLM2 may wavefront-modulate a laser beam from the laser light source 1, i.e., a laser beam 7 containing speckles, to generate a modulated beam having depth information. Specifically, according to the embodiment of the present disclosure, the SLM2 can spatially change the phase of the laser beam emitted from the laser light source 1, and thus can be used to process image information carried by the laser beam. According to an embodiment of the present disclosure, the SLM2 may perform wavefront modulation on the laser beam from the laser light source 1. It is known to those skilled in the art that common imaging techniques are only capable of rendering two-dimensional planar images because they lack depth information for the image. In this context, the reason why the AR system 10 presents a stereoscopic image using the holographic AR technology is that the SLM2 can make the presented image have depth information by performing wavefront modulation on the laser beam from the laser light source 1. Those skilled in the art will recognize that although embodiments of the present disclosure are described herein with the SLM2 being a transmissive SLM, such as a liquid crystal-based SLM, that passes the optical path of a laser beam through the SLM, the present disclosure is not limited thereto. According to other embodiments of the present disclosure, the SLM2 may also be a reflective SLM.
According to the embodiment of the present disclosure, as shown in fig. 1, the relay 3 can form the optical path of the relay modulated light beam and expand the angle of field.
In accordance with embodiments of the present disclosure, as shown in fig. 1, a combiner 5 may combine the modulated light beam from the relay with ambient light 4 for presentation to a human eye 9.
According to an embodiment of the present disclosure, the speckle suppressor 6 may suppress laser speckle by suppressing temporal and/or spatial coherence of the laser beam or the modulated beam, as shown in fig. 1. According to the embodiment of the present disclosure, as shown in fig. 1, the speckle suppressor 6 may be used in combination with at least one of the laser light source 1, the spatial light modulator 2, and the relay 3, and subjected to processing by the speckle suppressor to obtain a laser beam 8 without speckle.
Fig. 2 shows a schematic diagram of an example of the speckle suppressor 6 according to an embodiment of the present disclosure. As shown in fig. 2, the speckle suppressor 6 may be a phase adjuster 61 that suppresses the spatial coherence of the laser beam or the modulated beam by performing phase adjustment to suppress laser speckle, according to an embodiment of the present disclosure. Further, as shown in fig. 2, the phase adjuster 61 serving as the speckle suppressor may include a phase-adjustable superlens 61a and a fixed-phase superlens 61b according to an embodiment of the present disclosure.
According to the embodiment of the present disclosure, the phase-tunable superlens 61a and the fixed phase superlens 61b may be constituted by superlenses. According to an embodiment of the present disclosure, a superlens for implementing the phase-tunable superlens 61a and the fixed-phase superlens 61b may include a substrate and a plurality of structural units disposed on a surface of the substrate, arranged in an array, with a nanostructure disposed at a center position and/or an apex position of each of the plurality of structural units.
In particular, according to an embodiment of the present disclosure, the substrate of the superlens may be formed of, for example, quartz glass.
Fig. 3 shows a schematic plan view of the structural unit of a superlens used as a speckle suppressor. As shown in fig. 3, according to an embodiment of the present disclosure, each of the plurality of structural units may have a planar shape of a regular hexagon or a square. Specifically, the left side of fig. 3 illustrates a structural unit having a planar shape of a regular hexagon in which nanostructures are disposed at the center position and the vertex position of each hexagonal structural unit. Further, the right side of fig. 3 illustrates a structural unit having a square planar shape in which a nanostructure is disposed at a central position of each square structural unit. In fig. 3, the nanostructures are shown as nano-pillars having a circular cross-section. However, one skilled in the art will recognize that the present disclosure is not so limited and that nanostructures may have other shapes in cross-section. Further, according to embodiments of the present disclosure, the material of the nanostructure may be, for example, titanium oxide. Further, according to an embodiment of the present disclosure, the height of the nanopillar may be, for example, 500nm. Fig. 4 shows a graph of the diameter of the nanostructures versus phase and transmission (T).
Further, as shown in fig. 2, the speckle suppressor 6 may also be a wavelength adjustor 62 that suppresses laser speckle by performing wavelength adjustment to suppress temporal coherence of the laser beam or the modulated beam, where λ represents a wavelength, according to an embodiment of the present disclosure.
According to the embodiment of the present disclosure, the wavelength adjustor 62 serving as the speckle suppressor may adjust the wavelength of the laser beam in the same color wavelength range.
According to the embodiment of the present disclosure, three types of speckle suppressor 6, i.e., the phase-tunable superlens 61a, the fixed-phase superlens 61b, and the wavelength adjuster 62 may be used in combination with at least one of the light source 1, the SLM2, and the relay 5 according to design and application requirements.
According to an embodiment of the present disclosure, assuming that the time required to update the speckle pattern is t, the time t may also be the transition time of the phase change material crystalline/amorphous state. Further, assuming that the human eye response time is τ and the speckle contrast reduction degree is ε, the above parameters should satisfy the following relation:
as can be seen from equation (1), the smaller the time t required for updating the speckle pattern, the greater the speckle contrast reduction degree, and the less easily the human eye can distinguish the speckles after imaging.
Various embodiments of the present disclosure are described in more detail below with reference to fig. 5-12. In fig. 5 to 12, the same components as those shown in fig. 1 to 2 are denoted by the same reference numerals.
Fig. 5 shows a schematic diagram of the configuration of the AR system 10 according to the first embodiment of the present disclosure.
According to a first embodiment of the present disclosure, the AR system 10 may include a speckle suppressor 6 used in combination with the light source 1, and the speckle suppressor 6 may be a fixed phase superlens 61b serving as a phase adjuster 61. According to an embodiment of the present disclosure, the fixed phase superlens 61b may be a superlens having a random but fixed phase, which has a high transmittance for laser light. According to the first embodiment of the present disclosure, by continuously changing the position of the fixed phase superlens 61b so that the random phase thereof is superimposed on the phase of the laser beam emitted from the light source 1, the speckle patterns that are not coherent with each other can be updated, thereby achieving the purpose of suppressing the speckles.
In order to enable the fixed phase superlens 61b to shift positions relative to the light source 1, according to the first embodiment of the present disclosure, the phase adjuster 61 serving as a speckle suppressor may include an actuator (not shown) that can rotate or oscillate the fixed phase superlens 61b relative to the optical axis of the laser beam or the modulated beam, thereby changing its phase in space to change the optical phase of the laser beam. In this context, the optical phase refers to a laser phase value corresponding to a point at which the laser beam is incident on the fixed phase superlens 61b. According to the first embodiment of the present disclosure, the fixed phase superlens 61b changes the optical phase of the laser beam by constantly rotating or swinging to change the spatial coherence thereof, and updates each speckle pattern with a different phase to suppress speckle.
According to the first embodiment of the present disclosure, the fixed phase superlens 61b may be mounted on an actuator, and the actuator may be a motor that drives the fixed phase superlens 61b to periodically oscillate or rotate. According to the first embodiment of the present disclosure, the actuator may drive the fixed-phase superlens 61b to rotate or swing for phase adjustment, so that the laser beam impinges on different nanostructures at different times, resulting in a change in the optical phase of the transmitted laser beam in space, thereby changing the phase of speckle. According to the first embodiment of the present disclosure, the fixed phase superlens 61b driven by the actuator can continuously update different speckle patterns according to a preset frequency, so as to suppress the spatial coherence of the laser beam and achieve the purpose of suppressing speckles.
According to the first embodiment of the present disclosure, assuming that the wobble displacement amount required to update the speckle pattern is d, the wobble displacement amount d may also be the height of the nanostructure. Further, assume that the radian of rotation required to update the speckle pattern is ω 0 The radian of the rotation is omega 0 May be an angular arc corresponding to the period of the nanostructure. Further, assuming that the wobbling frequency is f, the rotational angular frequency is ω, and the diameter of the fixed-phase superlens 61b is D, the personThe eye response time is τ and the speckle contrast reduction is ε.
According to the first embodiment of the present disclosure, when the actuator drives the fixed-phase superlens 61b to swing along its central axis, the above parameters should satisfy the following relational expression:
as can be seen from equation (2), the larger the swing displacement d required for updating the speckle pattern is, the larger the speckle contrast reduction degree is, and the less it is easy for the human eye to distinguish the speckles after imaging.
Further, according to the first embodiment of the present disclosure, when the actuator drives the fixed-phase superlens 61b to rotate along the optical axis, the above-described parameters should satisfy the following relational expression:
as can be seen from equation (3), the larger the rotation angle frequency ω of the updated speckle pattern is, the larger the speckle contrast reduction degree is, and the more difficult it is for the human eye to distinguish the speckles after imaging.
According to the first embodiment of the present disclosure, the laser beam with speckle suppressed is irradiated on the combiner 5 after passing through the SLM2 and the relay 3 in order along the optical path, and the combiner 5 combines the external ambient light 4 with the laser beam modulated by the SLM2 to be reflected in the human eye.
The speckle reduction effect in the AR system according to the first embodiment of the present disclosure is described below with reference to fig. 6 to 8 in conjunction with specific examples.
Fig. 6 shows a phase distribution diagram of a fixed-phase superlens 61b serving as a speckle suppressor included in the AR system according to the first embodiment of the present disclosure. Fig. 7 shows a schematic diagram of speckle contrast of an AR system according to the prior art, and fig. 8 shows a schematic diagram of speckle contrast of an AR system according to a first embodiment of the present disclosure.
Specifically, the fixed phase superlens 61b is oscillated (vibrated) using an actuator in this example to change the phase distribution of the fixed phase superlens 61b with respect to the laser light source. The light source 1 may be a monochromatic laser that emits a laser beam having an operating wavelength λ of 550 nm. The fixed phase superlens 61b has a diameter D of 1mm and has a phase distribution as shown in fig. 6. In addition, assuming that the swinging displacement d required for updating the speckle pattern is 500nm, the swinging frequency f is 20kHz, the human eye response time t is 10ms, and the maximum speckle contrast reduction degree epsilon is 6%. According to the formula (2), the speckle contrast reduction degree is calculated to be 4.8%, and the value is less than the preset maximum speckle contrast reduction degree by 6%. That is, the modulated speckle complies with the preset requirements. Specifically, as shown in fig. 7 and 8, the laser speckle phenomenon is significantly reduced.
Fig. 9 shows a schematic diagram of the configuration of the AR system 10 according to the second embodiment of the present disclosure. The only difference between the AR system 10 according to the second embodiment of the present disclosure shown in fig. 9 and the AR system 10 according to the first embodiment of the present disclosure shown in fig. 7 is that a phase-adjustable superlens 61a is used as the speckle suppressor 6 instead of the fixed-phase superlens 61b (and the actuator for driving the same).
As shown in fig. 9, according to a second embodiment of the present disclosure, the AR system 10 may include a speckle suppressor 6 used in combination with the light source 1, and the speckle suppressor 6 may be a phase-adjustable superlens 61a serving as a phase adjuster 61. According to the embodiment of the disclosure, the phase-adjustable super lens 61a may change the micro-nano structure between the crystalline state and the amorphous state by changing the applied voltage, and since the refractive index of the micro-nano structure in the crystalline state is different from that in the amorphous state, the lattice state of the micro-nano structure is changed by changing the voltage applied to the phase-adjustable super lens 61a, so that the refractive index of the micro-nano structure is changed, and finally the phase distribution on the phase-adjustable super lens 61a is changed. Different speckle patterns can be continuously updated, so that the purpose of suppressing the speckles by suppressing the spatial coherence of the laser beam is achieved, and when the phase-adjustable super-surface 61a is used for suppressing the speckles, all parameters also meet the formula (1).
According to the first embodiment of the present disclosure, the optical performance of the superlens is mainly determined by two factors: one is the geometry and size of the structural unit, and the other is the dielectric constant of the material, if the above two factors can be changed, the adjustability of the superlens can be realized. Thus, the dielectric constant of the material can be changed to realize the regulation or reconstruction of the optical performance of the device. Thus, in addition to the electrically controllable tunable superlens described above, the phase tunable supersurface 61a may also be an optically and mechanically controllable tunable superlens.
Illustratively, the phase change material in the optically controlled tunable superlens can change the internal crystal lattice of a substance under an external excitation (such as laser), so that the dielectric constant can be greatly changed, and the tuning of the superlens is realized.
Illustratively, the mechanically controlled adjustable superlens can be formed by applying a flexible material to the superlens, applying a stretching force to the superlens, and changing the geometric shape and size of the structural unit, thereby realizing the adjustability of the superlens.
According to the second embodiment of the present disclosure, the laser beam with speckle suppressed is irradiated on the combiner 5 after passing through the SLM2 and the relay 3 in order along the optical path, and the combiner 5 combines the external ambient light 4 with the laser beam modulated by the SLM2 to be reflected in the human eye.
Fig. 10 shows a schematic diagram of the configuration of an AR system 10 according to a third embodiment of the present disclosure. The difference between the AR system 10 according to the third embodiment of the present disclosure shown in fig. 10 and the AR systems 10 according to the first and second embodiments of the present disclosure shown in fig. 7 and 9 is that a wavelength adjuster 62 is used as the speckle suppressor 6 instead of the phase adjuster 61.
As shown in fig. 10, according to the third embodiment of the present disclosure, the AR system 10 may include a speckle suppressor 6 used in combination with the light source 1, the speckle suppressor 6 may be a wavelength adjuster 62, wherein the light source 1 may be a wavelength tunable laser when integrally configured with the wavelength adjuster 62, and laser light emitted by the laser is irradiated onto a combiner 5 through an SLM2 and a relay 3 in turn along an optical path, and ambient light 4 from the outside is combined with a laser beam modulated by the SLM2 by the combiner 5 to be reflected in the human eye. According to the third embodiment of the present disclosure, the wavelength adjustor 62 may adjust the wavelength of the laser beam incident thereon within a certain range, and the difference between two adjacent wavelength adjustments should be smaller than the color difference recognizable by human eyes. Therefore, under the condition that the difference value of different wavelengths is smaller than the eye color difference which can be distinguished by human eyes, the speckle patterns updated by different wavelengths do not have fixed phase difference, so that the different speckle patterns are mutually incoherent, namely the time coherence of the laser beams is inhibited, and the laser speckle phenomenon is inhibited.
As shown in fig. 10, according to the third embodiment of the present disclosure, when the speckle suppressor 6 is the wavelength adjuster 62, the laser beam emitted from the laser light source 1 is first transmitted through the wavelength adjuster 62 to form a speckle pattern. According to the third embodiment of the present disclosure, the wavelength adjuster 62 may adjust the wavelength of the laser within a minimum wavelength difference range in which human eyes can distinguish color differences, the laser wavelengths transmitted through the wavelength adjuster 62 are different in time of continuous update so that speckle patterns formed by each wavelength are also different, and speckles are continuously updated without changing the color of the laser beam to achieve the purpose of suppressing speckles.
Further, according to the embodiment of the present disclosure, the number of the laser light sources 1 may be greater than or equal to two. For example, when the AR system 10 is configured to implement a color RGB display, a corresponding one laser light source 1 may be provided for each color of RGB, i.e., there are three laser light sources. At this time, according to an embodiment of the present disclosure, the number of wavelength adjusters may be the same as the number of laser light sources and respectively correspond to the respective laser light sources. For example, when the AR system 10 is configured to implement a color RGB display, one wavelength adjuster serving as a speckle suppressor may be provided for each of the laser light sources of RGB, i.e., there are three wavelength adjusters for individually suppressing speckles of the laser light of each color.
According to the third embodiment of the present disclosure, the laser beam with speckle suppressed is irradiated on the combiner 5 after passing through the SLM2 and the relay 3 in order along the optical path, and the combiner 5 combines the external ambient light 4 with the laser beam modulated by the SLM2 to be reflected in the human eye.
Fig. 11 shows a schematic diagram of a configuration of an AR system according to a fourth embodiment of the present disclosure. According to a fourth embodiment of the present disclosure, the AR system 10 may include a speckle suppressor 6 used in combination with the SLM2, the speckle suppressor 6 may be a phase-tunable superlens 61a.
According to the fourth embodiment of the present disclosure, a phase-tunable superlens 61a serving as the speckle suppressor 6 may be provided downstream of the SLM2 to phase-modulate the modulated light beam emitted from the SLM 2. According to the fourth embodiment of the present disclosure, by arranging the speckle suppressor 6 as one device alone and placing it in close proximity to the rear of the SLM2, it is possible to obtain a complex amplitude distribution on which independent random phases are superimposed based on the far field. Then, the speckle is suppressed by obtaining the phase distribution of the speckle suppressor 6 and further the phase distribution of the speckle pattern formed by the adjusted laser beam using a G-S (Gerchberg-Saxton) algorithm.
As shown in fig. 11, according to the fourth embodiment of the present disclosure, a laser beam emitted from a laser light source 1 is incident on a phase-tunable superlens 61a via an SLM2, a modulated beam with speckle suppressed is emitted from the phase-tunable superlens 61a, and is transmitted through a relay 3, and then ambient light 4 from the outside and the modulated beam are combined by a combiner 5 and are reflected to the human eye.
Further, according to the fourth embodiment of the present disclosure, the SLM2 may include a phase-tunable superlens 61a serving as the speckle suppressor 6, which can adjust the phase distribution by changing the voltage applied thereto while wavefront-modulating the laser beam to generate a modulated beam. In other words, the SLM2 may be integrally formed with the phase-tunable superlens 61a serving as the speckle suppressor 6 to simultaneously realize the functions of beam modulation and speckle suppression. Specifically, the speckle suppressor 6 is combined with the SLM2 to directly superpose a series of independent randomly changed phases on the complex amplitude generated by the SLM by using computational power within a preset human eye response time, and then the phases are displayed on the human eye, and then the purpose of suppressing the speckle is achieved by using the average effect.
Fig. 12 shows a schematic diagram of the configuration of the AR system 10 according to a fifth embodiment of the present disclosure.
According to a fifth embodiment of the present disclosure, the AR system 10 may include a speckle suppressor 6 used in combination with the repeater 3, and the speckle suppressor 6 may be a fixed-phase superlens 61b as a phase adjuster.
As shown in fig. 12, according to a fifth embodiment of the present disclosure, the relay 3 may be a 4f system based on a fixed phase superlens 61b. Specifically, as shown in fig. 12, assume that the distance between the SLM2 and the first lens 31 in the relay 3 is f 1 The distance between the first lens 31 and the fixed phase superlens 61b is f 2 The distance between the fixed phase superlens 61b and the second lens 32 is f 3 The distance between the second lens 32 and the combiner 5 is f 4 And f = f 1 ＝f 2 ＝f 3 ＝f 4 Where f is the focal length of the first lens 31 and the second lens 32. According to the fifth embodiment of the present disclosure, the frequency domain filter using the fixed phase superlens 61b has a small size and a fast response, and can filter out high frequency components in speckles to achieve the purpose of suppressing the speckles, and the 4f system can perform filtering transformation on the light waves, as follows:
wherein λ is the operating wavelength and f is the focal length.
The 4f system can adopt wafer level packaging, and has the advantages of high alignment precision and low calibration difficulty. According to the fifth embodiment of the present disclosure, as shown in fig. 12, the laser light source 1 emits a laser beam which is an ideal monochromatic plane wave. According to the fifth embodiment of the present disclosure, the laser beam passes through the SLM2, the relay 3 and the combiner 5, the unmodulated laser beam is reflected into human eyes, and then the phase distribution of the fixed phase superlens 61b in the 4f system is adjusted according to the speckle pattern received by the human eyes and the transfer function is changed, so as to weaken the high frequency component in the speckle, thereby achieving the effect of suppressing the speckle. According to a fifth embodiment of the present disclosure, the transfer function is as follows:
wherein H SLM Is the impulse response function of the spatial modulator, G ms As a function of the impulse response of the super-surface, H co As a function of the impulse response of the combiner, xe 0 Cut-off frequency, y, on the x-axis for the impulse response of the super-surface e0 Cutoff frequency, U, on the y-axis for the impulse response of the super-surface ms As a function of the amplitude and phase distribution of the super-surface.
According to an embodiment of the present disclosure, the 4f system can also be used to expand the field angle of the optical path, and the pixels of the SLM2 are reduced to a desired multiple and relayed to the projection lens by the 4f system, wherein the reduced pixels expand the field angle of the augmented reality system in the present application.
The present disclosure also provides a display device, which may comprise an AR system as described above
The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments disclosed in the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.
Claims (15)
1. An augmented reality system, comprising:
a laser light source;
a spatial light modulator configured to wavefront-modulate a laser beam from the laser light source to generate a modulated beam having depth information;
a relay configured to form an optical path that relays the modulated light beam;
a combiner configured to combine the modulated light beam from the relay with ambient light; and
a speckle suppressor configured to suppress laser speckle by suppressing temporal coherence and/or spatial coherence of the laser beam or the modulated beam, wherein the speckle suppressor is used in combination with at least one of the laser light source, the spatial light modulator, and the repeater.
2. The augmented reality system of claim 1, wherein the speckle suppressor is configured to satisfy the following relationship:
wherein epsilon is the target degree of the reduced laser speckle contrast, tau is the human eye response time, and t is the time required for updating the speckle pattern.
3. The augmented reality system of claim 1, wherein the speckle suppressor comprises a phase adjuster configured to suppress laser speckle by performing phase adjustment to suppress spatial coherence of the laser beam or the modulated beam.
4. The augmented reality system of claim 3, wherein the phase adjuster is comprised of a fixed phase superlens, the speckle suppressor further comprising an actuator configured to rotate the fixed phase superlens relative to an optical axis of the laser beam or the modulated beam, the rotation satisfying the following relationship:
wherein epsilon is the target degree of laser speckle contrast reduction, tau is the human eye response time, and omega 0 The radian of rotation required to update the speckle pattern is ω, the angular frequency of rotation.
5. The augmented reality system of claim 3, wherein the phase adjuster is comprised of a fixed phase superlens, the speckle suppressor further comprising an actuator configured to oscillate the fixed phase superlens relative to an optical axis of the laser beam or the modulated beam, the oscillation satisfying the following relationship:
wherein epsilon is the target degree of laser speckle contrast reduction, tau is the human eye response time, f is the oscillation frequency, D is the diameter of the phase adjuster, and D is the oscillation displacement required for updating the speckle pattern.
6. The augmented reality system of claim 3, wherein the phase adjuster is comprised of a phase-adjustable superlens that satisfies the following relationship:
wherein epsilon is the target degree of the reduced laser speckle contrast, tau is the human eye response time, and t is the time required for updating the speckle pattern.
7. The augmented reality system of claim 6, wherein the phase-tunable superlens is an electronically-controlled tunable superlens, an optically-controlled tunable superlens, or a mechanically-controlled tunable superlens.
8. Augmented reality system according to any one of claims 4 to 6, wherein the superlens comprises a substrate and a plurality of structural units arranged in an array provided on a surface of the substrate, a nanostructure being provided at a central position and/or an apex position of each of the plurality of structural units.
9. The augmented reality system of claim 8, wherein the planar shape of each of the plurality of structural units is a regular hexagon or a square.
10. The augmented reality system of claim 2, wherein the speckle suppressor comprises a wavelength adjuster used in combination with the laser light source configured to suppress laser speckle by performing wavelength adjustment to suppress temporal coherence of the laser light beam.
11. The augmented reality system of claim 10, wherein the number of the laser light sources is greater than or equal to two, and the number of the wavelength adjusters is the same as the number of the laser light sources and corresponds to the respective laser light sources, respectively.
12. Augmented reality system according to claim 10, wherein the laser light source is a wavelength tunable laser.
13. The augmented reality system of claim 1, wherein the spatial light modulator comprises a phase-tunable superlens serving as the speckle suppressor and configured to adjust a phase distribution by changing a voltage applied thereto while wavefront-modulating the laser beam to generate the modulated beam.
14. The augmented reality system of claim 1, wherein the relay comprises a 4f optical system, wherein a superlens serving as the speckle suppressor is provided at a center between two lenses of the 4f optical system, and is configured to filter out high frequency components in laser speckle.
15. A display device, comprising:
an augmented reality system according to any one of claims 1 to 14.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
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