Illumination optical systems

Abstract

This disclosure relates to an illumination optical system for a wearable AR display system, the illumination optical system comprising a spatial light modulator and a plurality of illuminators, the illuminators being arranged to illuminate the spatial light modulator, the spatial light modulator being arranged to modulate the light from the illuminators, and the light from each of the plurality of illuminators being incoherent with respect to each other. This disclosure also relates to a wearable augmented reality display comprising the illumination optical system.

Description

Technical Field

[0001] The present disclosure relates to an illumination optical system for a wearable augmented reality display. The present disclosure also relates to a wearable augmented reality display, particularly such a display including an optical combiner, and more particularly including a diffractive optical combiner.

Background Art

[0002] FIG. 1 is a generalized view of an augmented reality display that superimposes an image from a projector or image source onto, for example, the real-world field of view in a user's eye. The off-axis optical system 100 of FIG. 1 generally includes: a light source or image source 110 having an associated beam shaping optics 120; imaging optics 130; and an optical combiner 140. Generally speaking, the combination of the light source 110, the beam shaping optics 120, and the imaging optics 130 is called a projector, which provides an image that can be seen by the user's eye during use. The function of the optical combiner 140 is to direct the light from the projector towards the user's eye while allowing ambient external environmental light from the real-world field of view to pass through the optical combiner 140 and reach the user's eye, so that the image from the projector is superimposed on the real-world field of view. An example of the optical combiner 140 is a holographic optical element (HOE). The HOE directs the light from the light source 110 towards the pupil plane of the optical system, making it visible to the user's eye. Although not shown in FIG. 1, a spatial light modulator may be provided between the light source 110 and the optical combiner 140 to modulate the light from the light source 110 and provide a moving image to the user's eye via the optical combiner 140.

[0003] The optical combiner 140 has at least two independent optical axes 150, 160 as shown in Figure 1, the first optical axis 150 being the axis from the projector to the optical combiner 140, and the second optical axis 160 being the axis from the optical combiner 140 to the user's eye / pupil plane. Such a system is therefore known as an off-axis optical system. When used in applications such as head-mounted display systems or augmented reality display systems, the above type of optical combiner 140 is known to be advantageous because it provides high clarity, good efficiency, i.e., bright images at low light power, is compatible with spectacle lens prescriptions, and can be encapsulated in such lenses.

[0004] Furthermore, the spatial light modulator 112 is typically used to modulate light from the light source 110 to create a dynamic image. Typically, a diffuser is used to create multiple rays to illuminate individual pixels of the spatial light modulator 112 across the entire area of ​​the spatial light modulator. The problem is that if the light source is a coherent light source, the light illuminates the diffuser, and the diffuser generates multiple rays at each pixel location on the diffuser, resulting in speckle interference. The speckles then propagate through the system and appear to the user as an unwanted speckle pattern.

[0005] The problem with optical combiners 140, particularly diffractive optical combiners such as holographic optical elements and surface relief gratings, is the wavelength dependence of diffraction. Therefore, in the case of broadband image sources such as LEDs, the image is diffracted from the optical combiner to different positions for each component wavelength of the image source light. For example, longer wavelengths are diffracted from the optical combiner at a larger angle than shorter wavelengths. This problem is known as dispersion and results in chromatic aberration in the image diffracted from the optical combiner. Furthermore, off-axis diffraction systems separate light rays of different wavelengths more significantly than on-axis systems due to the wavelength dependence of diffraction. This effect increases as the deviation of the optical combiner 140 from the diffraction direction of light increases. Consequently, chromatic dispersion increases significantly in off-axis systems.

[0006] A known solution to the dispersion problem is to use an image source with a very narrow bandwidth. One such known narrowband image source is a laser diode. Laser diodes are advantageous for wearable augmented reality display applications due to their small size and relatively low power consumption. However, it is known that the narrower the bandwidth of a light source, the greater the time coherence of the light source, and ideally, if the light source is ideally monochromatic, it can have an infinite coherence length. One problem with this solution is that if the light source contains two or more such sources (narrowband image sources such as lasers with long coherence lengths) of the same wavelength, interference occurs when the narrowband light sources, such as laser diodes, illuminate the target. In the case of an augmented reality display of the type shown in Figure 1, this interference propagates through the system to the user's eye, and the interference pattern is visible to the user, degrading the visible image from the image source. [Overview of the project]

[0007] Therefore, the object of the embodiments disclosed herein is to avoid or mitigate one or more of the disadvantages discussed above.

[0008] Against this backdrop, according to the claims, an illumination optical system for a wearable AR display system and a wearable AR display including such an illumination optical system are provided. Other preferred and optional features are defined in other claims and discussed throughout this disclosure.

[0009] A more detailed description is given with reference to embodiments, some of which are shown in the accompanying drawings, so that the features of this disclosure may be understood in detail. However, it should be noted that the accompanying drawings show only typical embodiments and should not be considered limiting to the scope. The drawings are for the purpose of facilitating understanding of the disclosure and are therefore not necessarily drawn to scale. It should be noted that features shown in the drawings are exaggerated for illustrative purposes and dimensions should not be inferred (unless otherwise stated in the text or drawings). The advantages of the embodiments will become apparent to those skilled in the art by reading this description in conjunction with the accompanying drawings. In the drawings, similar reference numerals are used to designate similar elements, as follows: [Brief explanation of the drawing]

[0010] [Figure 1] This shows a generalized arrangement of a known off-axis optical system, including the illumination optics and optical combiner. [Figure 2] An embodiment of an illumination optical system and an optical combiner for a wearable augmented reality display is shown. [Figure 3] An embodiment of an illumination optical system and an optical combiner for a wearable augmented reality display is shown. [Figure 4] This example shows a wearable AR system in the form of a pair of AR glasses including an illumination optical system according to an embodiment. [Figure 5a] This illustrates the concept of eye box expansion by increasing the position of the eyes. [Figure 5b] This illustrates the concept of eye box expansion by increasing the position of the eyes. [Modes for carrying out the invention]

[0011] Figure 2 shows an illumination optical system 201 according to an embodiment. The illumination optical system 201 includes a plurality of illumination sources 202a, 202b, 202c and a spatial light modulator 204. To aid in understanding the operation of the illumination optical system 201, a diffractive optical combiner 206 is also shown, which shows the convergence of light rays from the illumination optical system 201 to the user's eye 210. Each of the illumination sources 202a, 202b, and 202c is positioned to form a corresponding eye position or image of the illumination source (also called the exit pupil of the illumination source) 208a, 208b, and 208c, respectively, which are the images of the illumination sources 202a, 202b, and 202c that are seen in the user's eye 210 when the combiner 206 is positioned within the user's field of view. In the context of a wearable AR display, the optical combiner is used to direct the image light from the illumination sources to the user's eye 210.

[0012] In this embodiment, the multiple illumination sources 202a, 202b, and 202c may be narrowband light sources. In the context of this application, narrowband light sources have a full width at half maximum (FWHM) of about 3.0 nm or less. The FWHM of an illumination source is the output optical spectral width, i.e., the width of the optical power spectral density of the optical output with respect to wavelength. The FWHM is measured between points on the optical spectrum where the power is attenuated to half of its peak value. For example, in a wearable AR display application, the illumination sources 202a, 202b, and 202c may be laser diodes having an FWHM, Δλ between about 0.1 nm and 3.0 nm. Such laser diodes may have a coherence length between about 0.20 nm and 1.50 nm. Laser diodes are also advantageous due to their relatively low power consumption and high output power (compared to LEDs), which enables relatively bright images and allows image content to be viewed under sunlight conditions. The illumination sources may be configured to operate in the visible spectral range of 380 nm to 700 nm.

[0013] Due to the dispersion effect problem mentioned above, it is impossible to use broadband light sources (i.e., those greater than approximately 3.0 nm), such as LEDs. However, high-power narrowband LEDs, such as superluminescent diodes (SLEDs), can be used as long as they have an FWHM of approximately 3.0 nm or less.

[0014] In this example, illuminators 202a, 202b, and 202c operate at the same light output wavelength λ. Advantageously, the light outputs from multiple illuminators 202a, 202b, and 202c are incoherent with each other, so that the light from illuminators 202a, 202b, and 202c enters the spatial light modulator 204 and becomes incoherent at the viewer's retina, thus reducing the interference effect between two or more illuminators 202a, 202b, and 202c. In the context of this disclosure, those skilled in the art will understand that the specific number of illuminators must be greater than two. Therefore, adjacent illuminators 202a, 202b, and 202c include any number of light sources that contribute to the viewer's perception of the image from those light sources, which are defined below as the eyebox. Illuminators not visible to the user within the eyebox do not need to be incoherent.

[0015] The illumination sources 202a, 202b, and 202c may be single-mode lasers, which provide an optical output with a bell-shaped far-field distribution and only one peak. In the case of single-mode lasers, the optical output can be reshaped to better fit the shape of the spatial light modulator 204 (e.g., a square top-hat profile). However, the use of multimode lasers results in a multi-peak illumination profile, leading to non-uniformity of illumination of the spatial light modulator. Multimode lasers are also known to generate unwanted patterns and speckles.

[0016] The spatial light modulator 204 is a dynamically controllable device capable of modulating the phase and / or amplitude of incident light from illumination sources 202a, 202b, and 202c. The spatial light modulator 204 modulates the light emitted by illumination sources 202a, 202b, and 202c to generate image content at eye positions 208a, 208b, and 208c. The spatial light modulator 204 is controlled by a suitable control processor (not shown) to generate image content at eye positions 208a, 208b, and 208c. Although the illustrated spatial light modulator 204 is transmissive, those skilled in the art will understand that the spatial light modulator 204 may also be reflective without departing from the scope of this disclosure. In the case of a reflective type, the illumination sources 202a, 202b, and 202c would be located on the same side of the spatial light modulator 204 as the illumination sources 202a, 202b, and 202c.

[0017] When the images from illumination sources 202a, 202b, and 202c are visible from a wide range of eye positions, the optical system is said to have a large eyebox. In the present application, the eyebox size depends on the number of illumination sources 202a, 202b, and 202c used, and more illumination sources create more eye positions and therefore a larger eyebox. In this way, those skilled in the art will recognize that the eyebox in this application is a combination of each eye position 208a, 208b, and 208c, providing a continuous range of eye positions from which images from each illumination source are visible. This concept is discussed in more detail below with reference to Figures 5a and 5b. In this example, the three illumination sources 202a, 202b, and 202c are shown in a 1D linear array, but any number of illumination sources 202a, 202b, and 202c may be provided in a linear array. Similarly, the illumination sources 202a, 202b, and 202c may be provided as a 2D rectangular array or in any suitable shape, depending on the requirements of the wearable AR display system. The adjacent eye positions 208a, 208b, and 208c may be discrete and separated from each other, as shown in the figure, or they may be adjacent to each other. Alternatively, the adjacent eye positions 208a, 208b, and 208c may overlap. Increasing the separation of the eye positions 208a, 208b, and 208c corresponds to increasing the field of view, and decreasing the separation of the eye positions 208a, 208b, and 208c corresponds to decreasing the field of view. One advantage of the illumination sources 202a, 202b, and 202c arranged as a 1D linear array is that the illumination optics can be incorporated into a small volume or folded, allowing them to be incorporated into wearable AR display systems such as AR glasses (discussed below, see Figure 4) where space is limited. For example, the arms of the glasses have a flattened cross-section that fits the human head.

[0018] Figure 3 shows an illumination optical system 301 according to a further embodiment. The illumination optical system 301 includes a plurality of illumination sources 314a, 314b, 314c and a spatial light modulator 304. To aid in understanding the operation of the illumination optical system 301, a diffractive optical combiner 306 is also shown, which shows the convergence of light rays from the illumination optical system 301 to the user's eye 310. Each of the illumination sources 314a, 314b, 314c is positioned to form the corresponding eye positions (or exit pupils) 308a, 308b, 308c, which are images of the illumination sources 314a, 314b, 314c as seen in the user's eye 310 when the optical combiner 306 is positioned within the user's field of view.

[0019] In the configuration shown in Figure 3, the multiple illumination sources 314a, 314b, and 314c are outputs of their respective optical guide elements 312a, 312b, and 312c. The inputs of the optical guide elements 312a, 312b, and 312c are optically coupled to the common light source 302 by an appropriate optical guide element in-coupler (not shown). The optical guide elements 312a, 312b, and 312c are of different lengths, which provides different optical path lengths (distance from the output of optical guide elements 312a, 312b, and 312c to the spatial light modulator) for light from the common light source 302 to propagate along each optical fiber to the respective outputs of the optical guide elements 312a, 312b, and 312c. The difference in optical path length introduced by the optical guide elements 312a, 312b, and 312c makes the light emitted from each of the multiple outputs of the optical guide elements 312a, 312b, and 312c incoherent with each other, thereby reducing the effect of interference between two or more illumination sources 314a, 314b, and 314c. The common light source 302 may be a single-mode laser diode. In the context of this disclosure, those skilled in the art will understand that the specific number of illumination sources must be greater than two. Thus, adjacent illumination sources 314a, 314b, and 314c include any number of light sources that contribute to the viewer's perception of the image from those light sources, which are defined below as the eyebox. Illumination sources not visible to the user within the eyebox do not need to be incoherent.

[0020] The optical waveguide elements 312a, 312b, 312c may be of any single-mode structure and may have any suitable refractive index distribution, i.e., a step or graded index. Those skilled in the art will understand that the optical waveguide elements 312a, 312b, 312c can be any optical waveguide structure such as an optical fiber, a slab waveguide, a planar waveguide, a strip waveguide, a rib waveguide, or a laser-scribed waveguide that uses total internal reflection to guide electromagnetic waves of the optical spectrum, as long as the outputs of each optical waveguide structure are temporally incoherent with each other. The optical waveguide may be a light pipe or a light guide that guides light by classical reflection.

[0021] Furthermore, in the arrangement of FIG. 3, the common light source 302 may be a narrowband light source. In the context of this arrangement, the narrowband light source has a full width at half maximum (FWHM) of 3.0 nm or less. The FWHM of the light source is the width of the output optical spectrum, i.e., the width of the optical power spectral density of the optical output with respect to the wavelength λ. The FWHM is measured between the points on the optical spectrum where the power has decayed to half of the peak value. For example, in wearable AR display applications, the common light source 302 may be a laser diode having a FWHM, Δλ, between 0.1 nm and 3.0 nm. Also, the laser diode is advantageous due to its relatively high output power (compared to an LED), which enables a relatively bright image and allows the image content to be viewed under sunlight conditions.

[0022] Due to the problem of the dispersion effect mentioned above, it is impossible to use a broadband light source (i.e., greater than about 3.0 nm), such as an LED. However, a high-power narrowband LED, such as a superluminescent diode (SLED), can be used as long as it has a FWHM of about 3.0 nm or less. The common light source 302 may be configured to operate in the visible spectrum range from 380 nm to 700 nm.

[0023] The spatial light modulator 304 modulates the light emitted by the illumination sources 314a, 314b, and 314c to generate image content at eye positions 308a, 308b, and 308c. The spatial light modulator is controlled by a suitable control processor (not shown) to generate image content at eye positions 208a, 208b, and 208c. Although the illustrated spatial light modulator 304 is transmissive, those skilled in the art will understand that the spatial light modulator 304 may also be reflective without departing from the scope of this disclosure. In the case of a reflective type, the illumination sources 314a, 314b, and 314c would be located in the spatial light modulator 304 on the same side as the user's eye 310.

[0024] Although not shown in the arrangements of Figures 2 and 3, those skilled in the art will understand that lenses or suitable optical systems in the form of lenses are required to couple light from the illumination optics 201, 301 to the spatial light modulators 204, 204, and that the imaging optics are arranged to couple light from the spatial light modulators 204, 304 to the optical combiners 206, 306. Those skilled in the art will also understand that suitable aberration control optics may be included.

[0025] Regarding the operation, the image light emitted from the illumination sources 202a, 202b, 202c, and 314a, 314b, 314c is incident on the spatial light modulators 204, 304. The image light is modulated by the spatial light modulators and passes through the optical combiners 206, 306, where it is diffracted to the eye positions 208a, 208b, 208c, and 308a, 308b, 308c. The light passing through or reflected from the spatial light modulators 204, 304 is modulated by amplitude, phase, or polarization modulation (or any combination thereof) by applying an appropriate electrical signal to the spatial light modulators 204, 304. By modulating the image light, appropriate display images are created at the eye positions 208a, 208b, 208c, and 308a, 308b, 308c. Regarding the arrangement of FIG. 3, the image light from the common light source 302 is coupled to each of the light guide elements 312a, 312b, 312c and propagates to the ends of the light guide elements 312a, 312b, 312c corresponding to the illumination sources 314a, 314b, 314c. Considering the refractive index, the distance through a single pixel of the spatial light modulator 304 from the common light source 302 through the light guide elements 312a, 312b, 312c and via the combiner 206 to the user's eye 310 defines the optical path of the light from the illumination source. By appropriately selecting the lengths of the light guide elements 312a, 312b, 312c, the optical path length can be defined such that the light emitted from the illumination sources 314a, 314b, 314c becomes incoherent at the user's eye 310. In other words, an optical path difference is introduced such that the light becomes incoherent. Those skilled in the art will also understand that an optical path difference can be introduced by providing a phase shift, for example, by including optical elements such as electro-optic modulation, piezoelectrically moving mirrors, different refractive indices of each of the light guide elements, or piezoelectric crystals that provide an electric field-induced optical path length change.

[0026] The optical combiners 206, 306 according to the embodiment allow external or ambient light to pass to the user's eyes 210, 310, and at the same time redirect rays from illumination sources 202a, 202b, 202c, 314a, 314b, 314c to the user's eyes 210, 310, so that both external light and rays are visible to the user. The optical combiners 206, 306 may include at least one diffraction element, such as a holographic optical element, a volume diffraction grating, a surface relief diffraction grating, or a reflection grating. The optical combiners may be provided on or inside a transparent substrate, such as an eyeglass lens.

[0027] As will be understood by those skilled in the art, the spatial light modulators 204, 304 may be of any suitable type, such as a liquid crystal on silicon (LCoS, which is an example of a reflective spatial light modulator), a liquid crystal display (LCD, which is an example of a transmissive spatial light modulator), a digital light processor (DLP), or a digital micromirror device (DMD). The spatial light modulators 204, 304 and the common 302 or the multiple illuminators 202a, 202b, 202c may be controlled by any suitable control processor (not shown), the specific details thereof are outside the scope of this disclosure.

[0028] The common light source 302 or illumination sources 202a, 202b, 202c may provide single-wavelength light, i.e., one of the red, green, or blue wavelengths of light. Alternatively, the common light source 302 or illumination sources 202a, 202b, 202c may be a so-called tricolor laser diode module, which typically consists of red, green, and blue (RGB) laser diodes integrated into a single device package.

[0029] Figure 4 shows a wearable augmented reality display 400 (not shown in Figure 4) which includes at least one of the illumination optics 201, 301 described above. This wearable augmented reality display takes the form of a wearable head-up display, such as a pair of glasses. Similar to known types of glasses, the wearable augmented reality display 400 includes a frame 402. The frame 402 includes an arm 404 and a lens mounting portion 406 connected by a bridge portion 408. One of the arms 404 includes a mounting portion 410 to which the illumination optics 201, 301 are fixedly attached, so that light from the illumination optics 201, 301 enters a spectacle lens 412 which includes the optical combiners 206, 306 described above.

[0030] Those skilled in the art will understand that the illumination optics 201, 301 are mounted on an arm 404 adjacent to a lens mounting portion 406 that holds an spectacle lens 412 and an optical combiner 206, 306. Standard ophthalmic lenses may be inserted into the other lens mounting portion. Alternatively, spectacle lenses including optical combiners may be mounted in the other lens mounting portion, and additional illumination optics 201, 301 may be mounted on the corresponding mounting portion of the second arm 404.

[0031] One or both of the arms 404 may be adapted to house a battery (not shown) that supplies power to the illumination optics 201, 301. Furthermore, one or both of the arms 404 may also include control electronics (not shown) for controlling the operation of the illumination optics 201, 301.

[0032] In the context of wearable AR display systems, and more generally in myopic optical devices such as telescopes and binoculars, the concept of the eyebox is the range of eye positions from which a user can view the images provided by the device or display. This concept is well-known in the field of augmented reality displays. The size and shape of the eyebox affect the user experience of a wearable AR display system. If a wearable AR display system has a small eyebox centered on the pupil of a user looking straight ahead, some or all of the displayed content may be invisible when the user looks away from the center. Furthermore, if the display has a small eyebox and is configured to align the eyebox with the pupil of a particular user, the eyebox may be misaligned for different users, for example, due to variations in interpupillary distance (IPD) from one user to the next. To overcome the problem of eyebox misalignment, AR display systems are generally designed to have a large eyebox to be applicable to a wide range of users. According to this disclosure, as shown by a comparison of Figures 5a and 5b, eyebox expansion can be achieved by increasing the number of eye positions from one eye position 208a in Figure 5a to three eye positions 208a, 208b, and 208c in Figure 5b. Although the eyebox expansion in Figure 5b is horizontal, those skilled in the art will recognize that eyebox expansion may also be vertical and / or horizontal. Eyebox expansion is achieved by increasing the number of illumination sources 202a, 202b, 202c or 314a, 314b, and 314c of the illumination optics 201 and 301 described above. The size of the eye positions is determined by the size of the exit pupils of the illumination sources 202a, 202b, 202c or 314a, 314b, and 314c. Although eye positions 208a, 208b, and 208c in Figure 5b are shown separated, they may be adjacent or overlapping, which should be noted as reducing the size of the eyebox in horizontal and / or vertical dimensions.

[0033] A further advantage of having multiple illuminators 202a, 202b, 202c or 314a, 314b, 314c according to the embodiment is that multiple rays from the multiple illuminators 202a, 202b, 202c or 314a, 314b illuminate the pixels of the spatial light modulators 206, 306, thus eliminating the need for diffusers (discussed in relation to Figure 1 above) and thus reducing speckle.

[0034] As mentioned above, one advantage of the illumination sources 202a, 202b, and 202c arranged as a 1D linear array is that the illumination optics can be incorporated into or folded into a small volume. A further effect is that when the 1D array is positioned horizontally to the user's eye, the eyebox is also oriented horizontally to the user's eye, as shown in Figure 5b. This has the advantage that the eyebox is longest in the direction of the IPD, and therefore more eye positions accommodate a wider range of IPDs, and thus accommodate a wider range of users of the wearable AR display. Those skilled in the art will also understand that the introduction of mirrors allows for the physical reorientation of the array of illumination sources relative to the spatial light modulator and / or optical combiner.

[0035] Specific and preferred embodiments of the disclosure are described in the attached independent claims. Combinations of features from dependent and / or independent claims may be appropriately combined, not limited to those described in the claims.

[0036] The scope of this disclosure includes any novel features or combinations of features disclosed expressly or implicitly, or any generalization thereof, whether relating to the requested disclosure or mitigating any or all of the issues addressed by this disclosure. The applicant will be notified that new claims may be formulated for such features during the examination of this application or any further such application derived therefrom. In particular, with reference to the attached claims, features from dependent claims may be combined with those from independent claims, and features from each independent claim may be combined in any suitable manner, not only in the specific combinations enumerated in the claims.

[0037] Features described in the context of separate embodiments may be provided in combination in a single embodiment. Conversely, various features described in the context of a single embodiment for the sake of brevity may be provided separately or in any suitable partial combination.

[0038] The term “including” does not exclude other elements or steps, and the terms “a” or “an” do not exclude plurals. The reference numerals in a claim shall not be construed as limiting the scope of the claim.

Claims

1. An illumination optical system for a wearable AR display system, wherein the illumination optical system includes a spatial light modulator and a plurality of illumination sources. The plurality of illumination sources are arranged to illuminate the spatial light modulator, and the spatial light modulator is arranged to modulate the light from the plurality of illumination sources. An illumination optical system in which light from adjacent light sources is incoherent to each other.

2. The illumination optical system according to claim 1, wherein the light from each of the plurality of illumination sources is temporally incoherent with respect to each other.

3. An illumination optical system in which each of the aforementioned multiple light sources generates a corresponding set of eye positions.

4. The illumination optical system according to any one of claims 1 to 3, wherein each of the plurality of illumination sources is a narrowband light source.

5. The illumination optical system according to claim 4, wherein each of the plurality of narrowband light sources has an FWHM between 0.1 nm and 3.0 nm.

6. The illumination optical system according to claim 4 or 5, wherein each of the plurality of narrowband light sources has a coherence length between approximately 0.20 nm and 1.50 nm.

7. The illumination optical system according to claim 4, wherein each of the narrowband light sources is a laser diode.

8. The illumination optical system according to claim 7, wherein the laser diode is configured to operate at the same emission wavelength.

9. The illumination optical system according to claim 7, wherein the laser diode is configured to operate in the range of 380 nm to 700 nm.

10. The illumination optical system according to claim 1, wherein each of the illumination sources includes an optical guide element, and each of the optical guide elements is optically coupled to a common light source.

11. The illumination optical system according to claim 10, wherein the common light source includes a narrowband light source, and the narrowband light source is a laser diode.

12. The illumination optical system according to claim 3, wherein the optical path lengths from the common light source to the position of each eye are different.

13. The illumination optical system according to any one of claims 1 to 12, wherein the spatial light modulator is a transmissive spatial light modulator or a reflective spatial light modulator.

14. The illumination optical system according to prior claim 7, wherein the laser diode is an RGB laser diode module.

15. A wearable AR display comprising the illumination optical system described in any one of claims 1 to 14.

16. The wearable AR display according to claim 15, further comprising a diffractive optical combiner configured to direct light from the illumination optical system to the position of the eyes, wherein the number of illumination sources corresponds to the number of eye positions.

17. The wearable AR display according to claim 15, wherein the diffractive optical combiner is one of a holographic optical element, a volume diffraction grating, a surface relief diffraction grating, or a reflection grating.

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