Waveguide configuration

Abstract

According to an example aspect of the present invention, there is provided a light guide arrangement comprising: an optical system configured to generate a configurable image encoded in a light field; and at least one light guide arranged to receive light from the light field and to transmit light to a plurality of locations in the light guide for emission, creating a waveguide-based display; the optical system comprising a light source having a wavelength λ1; and the light guide comprising a notch filter element having a stop band at wavelength λ1' disposed on an outer surface of the light guide to prevent leakage of light from the light field, the stop band at wavelength λ1' filtering light of wavelength λ1 incident on the notch filter element at a first angle of incidence.

Description

[Technical field]

[0001] FIELD This disclosure relates to managing colored light using light guides. [Background technology]

[0002] Light guides are capable of transmitting light at optical frequencies. Optical or visible frequencies refer to light having wavelengths between about 400 and 700 nanometers. Light guides are employed in displays where light from a primary display may be transmitted using one or more waveguides to a suitable location for emission to a user's eye or eyes.

[0003] Light guide displays may be mounted in head mounted glasses or helmets and may be suitable for augmented reality or virtual reality type applications. In augmented reality, a user sees a view of the real world with a complementary display overlaid on top. In virtual reality, a user loses their view of the real world and is instead provided with a view into a software defined landscape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application No. 15812618.5 [Non-patent literature]

[0005] [Non-Patent Document 1] https: / / www.optilayer.com / notch-filters Summary of the Invention [Means for solving the problem]

[0006] Some aspects provide the subject matter of the independent claims. Some embodiments are defined in the dependent claims.

[0007] According to a first aspect of the present disclosure, there is provided a light guide arrangement comprising: an optical system configured to generate a configurable image encoded in a light field; and at least one light guide arranged to receive light from the light field and to transmit light to a plurality of locations in the light guide for emission, creating a waveguide-based display; the optical system comprising a light source having a wavelength λ1; and the light guide comprising a notch filter element having a stop band at wavelength λ1' disposed on an outer surface of the light guide to prevent leakage of light from the light field, the stop band at wavelength λ1' filtering light of wavelength λ1 incident on the notch filter element at a first angle of incidence.

[0008] According to a second aspect of the present disclosure, there is provided a method that includes manipulating a light guide arrangement using an optical system to generate a configurable image encoded in a light field, and receiving light from the light field into at least one light guide and transmitting the light to a plurality of locations in the light guide for emission to create a waveguide-based display, the method comprising: the optical system comprising a light source having a wavelength λ1; the light guide having a notch filter element having a stop band at wavelength λ1' disposed on an outer surface of the light guide to prevent leakage of light from the light field, the stop band at wavelength λ1' filtering light of wavelength λ1 incident on the notch filter element at a first angle of incidence.

[0009] According to a third aspect of the present disclosure, there is provided a non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, causes an apparatus to at least generate a configurable image encoded in a light field using an optical system and transmit light from the light field to at least one light guide arranged to receive light and transmit light to a plurality of locations in the light guide for emission, producing a waveguide-based display, wherein the optical system comprises a light source having a wavelength λ1, the light guide having a notch filter element having a stopband at wavelength λ1' disposed on an outer surface of the light guide to prevent leakage of light from the light field, the stopband at wavelength λ1' filtering light of wavelength λ1 incident on the notch filter element at a first angle of incidence.

[0010] According to a fourth aspect of the present disclosure there is provided a computer program configured to perform the method according to the second aspect. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates an example system in accordance with at least some embodiments of the present invention. [Figure 2A] FIG. 1 illustrates an example system in accordance with at least some embodiments of the present invention. [Figure 2B] FIG. 1 illustrates an example system in accordance with at least some embodiments of the present invention. [Figure 3A] 11 is a graph of the spectra and transmittance of light sources and filters of an example system in accordance with at least some embodiments of this invention. [Figure 3B] 11 is a graph of the spectra and transmittance of light sources and filters of an example system in accordance with at least some embodiments of this invention. [Figure 4] FIG. 1 illustrates an example device capable of supporting at least some embodiments of the present invention. [Diagram 5]1 is a flow diagram of a method in accordance with at least some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] By using a light source such as a laser or light emitting diode (LED), an improved waveguide-based display can be constructed as described herein below. In particular, using multiple visible light wavelengths to generate a single color in a waveguide-based display, a color can be rendered across the waveguide-based display by appropriately mixing the colors. It may also be desirable for a user to not only view an image on a waveguide display, but also for as little light as possible to leak therefrom to the outside world. In a typical waveguide display, the display leaks light through the exterior surface of the waveguide display. With some embodiments of the present invention, this leakage can be reduced or nearly completely eliminated by employing a notch filter layer applied over the exterior surface of the waveguide display, as described below.

[0013] FIG. 1 illustrates an example system in accordance with at least some embodiments of the present invention. The system includes a light source 140, in this case three light sources R, G, and B. In some embodiments, the system may include one to four light sources. The light sources may include, for example, laser or LED light sources, with laser light sources having the advantage that they are more strictly monochromatic than LEDs. The light sources 140, along with an optional mirror 130, are configured to create a light field in angular space that can be used to cause a waveguide display to generate its image. The image is encoded in the light field. The light field is illustrated diagrammatically as field 100 in FIG. 1. In some embodiments, a physical primary display may display an image of the light field, while in other embodiments, the system does not include a physical primary display and the image is simply encoded in the light field distributed in angular space. Light 104 from the light field 100 may be transmitted to the light guide 110 directly or using a light guide 102, for example, comprising mirrors and / or lenses. The light guides 102 are optional in the sense that they may not be present, depending on the specifications of a particular embodiment, in other words, the light guides 102 are not present in all embodiments.

[0014] To guide the light 104 into the waveguide 110, an in-coupling structure such as a partially reflective mirror, a surface relief grating, or other diffractive structure may be used to direct the incoming light into the waveguide 110, as is known in the art. In some embodiments, the light 104 may be in-coupled from an end of the waveguide. In the waveguide 110, the light 104 travels forward by being repeatedly reflected inside the waveguide until it interacts with element 112a, which deflects the light 104 out of the waveguide 110 into air toward the eye 120 as light ray 114 creating an image. Elements 112a and 112b may include, for example, a partially reflective mirror, a surface relief grating, or other diffractive structure. Element 112a may be positioned to spread the light field 100 inside the waveguide 110 such that, for example, the image of the waveguide display is precisely generated. Light from different angular portions of the light field 100 interact with the elements 112 such that light rays 114 create the image encoded in the light field 100 on the retina of the eye 120. The elements 112a and 112 may be the same element, either partially or entirely. In other words, in some embodiments there is a single set of elements, and in other embodiments there are two separate sets of elements 112a, 112. The elements 112 cause the light to exit the waveguide 110 at an exit position. As a result, the user perceives the image encoded in the light field 100 in front of the user's eye 120. Since the waveguide 110 may be at least partially transparent, the user may also advantageously view the user's real surroundings through the waveguide 110, for example, when the waveguide-based display is head-mounted. Light is emitted from the waveguide 110 at multiple angles at multiple positions of the elements 112 as a result of the action of the elements 112a and 112.

[0015] The term "color space" refers to a (two-dimensional) chromaticity diagram that corresponds to the perceived colors resulting from the spectral response of the average human eye. The color gamut of a device is the region of color space that is reproducible by that device. Specifically, the color gamut here corresponds to the region in color space that can be reproduced by the combination of light source 140 and waveguides in the system for the light field that an observer perceives as emanating from the focal plane. A Region of Interest (ROI) then refers to the region of color space that is sufficient to reproduce what is perceived as a full-color image, but may correspond to a smaller or larger region of color space. Since a particular point in color space can be reached by different combinations of wavelengths, a particular ROI can be reached using different combinations of distinct spectral features, such as peaks in the visible spectrum.

[0016] A color image can be generated, for example, by assuming that the user's color vision perception corresponds to a standard eye and by reproducing (a part of) the corresponding color space. As is clear from the definition of the color space, the user perceives the same color as a result of several different optical signal spectra. This allows freedom in how the waveguide 110 operates. In addition, different combinations of distinct spectral characteristics, such as wavelengths, can be used to generate the same color. How the light is coupled out of the waveguide can be a function of the exit position. That is, a light ray corresponding to a particular position (a particular propagation angle) in the input image can exit the waveguide at different angles depending on the exit position. In general, the user can perceive the same color from multiple spectra of the optical signal 114. This allows freedom in the manufacture of the waveguide 110. Specifically, we note that the same color stimulus can be reproduced at each pixel if the ROI is selected to be located at the intersection of the color gamuts corresponding to the effective wavelengths of each individual pixel. Therefore, pixel-by-pixel modulation or filtering of the light source does not impose fundamental limitations on which colors can be reproduced by the system.

[0017] In a waveguide-based display, multiple waveguides 110 may be present, for example to enhance image transmission capabilities, as well as, optionally, to transmit light for a user's other eye, which is not illustrated in FIG. 1 for clarity of illustration.

[0018] The image-encoding light field 100 may be generated using an optical system that includes, for example, a mirror 130 and light sources R, G, and B. The mirror 130 may include, for example, a microelectromechanical (MEMS) mirror configured to reflect light from a light source 140, such as a laser, to generate the image-encoding light field 100 in a controlled manner, for example, by scanning the angle space 100, thereby generating the image-encoding light field. The mirror 130 may thus be actuated to tilt at different angles to direct light from the light source 140 to appropriate portions of the light field 100 in the angle space. In some embodiments, the optical system may comprise other types of image generating devices, such as a projector, where the light source may be, for example, an LED, and the primary display may be in the form of a liquid crystal on silicon (LCOS) device. The optical system may include, for example, a light source and a MEMS actuator configured to provide light from the light source in the angle space, thereby generating the light field for input to the waveguide 110.

[0019] The system illustrated in FIG. 1 comprises three light sources 140. This is an illustrative example that does not limit the disclosure, rather, there may be fewer or more than three light sources. For example, in certain embodiments, a monochrome display is made with only one light source. The light sources 140 may be monochromatic in the sense that they produce a narrow spectral band of light with a single peak wavelength, as in lasers, or their spectral band may be broader, as with LEDs. Light sources with more complex spectral distributions are also possible. In principle, any color space visible to humans can be produced by appropriately exciting the photoreceptors of the retina. Typically, this is achieved by mixing three wavelengths of light, for example, one wavelength each in the red, green, and blue portions of the visible spectrum.

[0020] Laser lights have such a narrow bandwidth that they can be considered monochromatic. Monochromatic can mean, for example, that the bandwidth of the light produced by the laser is, for example, narrower than 0.1 nanometers, or narrower than 2 nanometers. The laser light sources can be modulated in their wavelength as a function of the angle of the light beam corresponding to the pixel of the image by using a laser light source with a selectable wavelength, such as an open cavity diode laser with a piezoelectric selectable cavity length, used in tuned combination with a mirror 130, which can be, for example, a MEMS mirror. The laser light source can include one or more lasers. The multiple lasers can have the same or different wavelengths.

[0021] LED light sources have a wider wavelength range than lasers. They can also have their wavelength modulated as a function of angle. For example, they can be made monochromatic on a pixel-by-pixel basis by filtering with a passband filter, the central wavelength of the passband being selectable. An even better approach to obtain monochromatic illumination of a given pixel using LEDs is to disperse the light output from the LED by diffraction and / or by refraction so that the desired wavelength is directed to the given pixel. Other means to achieve a distribution of central wavelengths across the pixel are of course also possible. Most importantly, this can be done in such a way that there is a correspondence between the propagation angle of the light ray representing the pixel inside the waveguide and its (central) wavelength. Moreover, this correspondence can be (closely) matched to the variation of the filtered wavelength band with respect to the angle of incidence, which typically occurs in notch filters. LED light sources can be used in LCOS implementations. Alternatively or additionally, lasers and suitable optical elements can be used instead of LED light sources. Typically, a notch filter may have a stop band with a width of, for example, at most 2 nanometers or at most 3 nanometers.

[0022] To create a color image encoded in the light field of angle space 100, light source 140 may be controlled, for example, by a program. In examples where mirror 130 is present, light source 140 and mirror 130 may be synchronized with each other such that light from light source 140 illuminates certain angular regions of light field 100 in a controlled manner to create a display of a color image therein that reproduces a still or moving input image received from an external source, such as a virtual reality or augmented reality computer. The still or moving image received from the external source may include, for example, a digital image or a digital video feed. The image encoded in light field 100 is thus configurable by providing an appropriately selected input image.

[0023] To create a particular color at a given face in angle space 100, that given face in angle space 100 may be illuminated by one or more light sources 140, for example a set of three or more light sources 140. That particular color is then reproduced by light ray 114 when light from the given face in angle space 100 travels within waveguide 110 to element 112, where it is emitted at an angle corresponding to the given face in angle space 100.

[0024] Light leakage through the exterior surface 202 of the waveguide display is undesirable as it reduces the brightness of the image seen by the user and alerts others that an image is being displayed. Furthermore, the leaking light may be annoying and flickering, or even make the image content itself visible. In the optimal case, light only leaves the waveguide 110 in a controlled manner through the interior surface 201 of the waveguide 110. To mitigate light leakage through the exterior surface 202, a notch filter element 200 is attached to the exterior surface 202. The notch filter element may be a diffraction grating, or may consist of a nearly transparent film that includes a notch filter designed to prevent light of a wavelength that matches the light source 140 from passing, but to pass light of other wavelengths. Thus, the user can see through the waveguide 110, but the leakage of certain light from the light source 140 is reduced. The notch filter may be realized, for example, as a stack of thin homogeneous (dielectric) layers, where the properties of the filter are determined by the number of layers, the thickness of each layer, and the material of the layers. Typical layer materials include SiO2 and TiO2. Generally, dielectric filters are reflective filters. To build an absorptive filter, an absorbing material such as a metal is required.

[0025] Generally, since the image transmitted through the waveguide 110 consists of a set of narrow wavelength bands (or even a single narrow wavelength band), blocking it using one or more notch filters only involves a small portion of the visible spectrum, and therefore the user's visibility through the waveguide 110 is largely unaffected. This is because the light field that the user sees around him / her includes a wide range of visible wavelengths. The notch filters therefore have a minimal effect on the amount of light information that the user sees from around him / her. The notch filters in the waveguide 110 may reflect the light that is not passed, such that the reflective filters provide the technical benefit of preserving the light intensity in the waveguide. Separate absorptive notch filter structures may be placed on the outer surface of the filter element 200 to attenuate the mirror-like effect of the waveguide that the reflective notch filters have on people around the user. Thus, there are four options for positioning the notch filter: first, a purely absorptive notch filter; second, a purely reflective notch filter; third, a reflective notch filter facing the user, with the absorptive notch filter covering the reflective notch filter on the outside; and fourth, a diffractive notch filter, whose behavior may depend on the side the light is incident on it, and is therefore the most commonly chosen.

[0026] 2A and 2B illustrate an example system in accordance with at least some embodiments of the present invention. Like numbering indicates similar structures as in FIG. 1. In FIG. 2A, three light sources 140 are individually identified as Light Source B, Light Source G, and Light Source R. For example, Light Source B may be in the blue portion of the visible spectrum, Light Source G may be in the green portion of the visible spectrum, and Light Source R may be in the red portion of the visible spectrum. In general, the light sources may be in the visible portion of the spectrum.

[0027] In Figure 2A, light sources B, G and R are used to produce a particular color in an angular portion 100a of a light field 100. The particular color is determined by the relative intensities of light sources B, G and R, and the brightness of the color is determined by the sum of the intensities of these light sources.

[0028] 2B, light sources B, G, and R are used to generate a particular color, for example the same color as in FIG. 2A, in angular portion 100b of light field 100. Angular portion 100b is in a different angular portion of the light field than where angular portion 100a is. The particular color is determined by the relative intensities of light sources B, G, and R, and the brightness of the color is determined by the sum of the intensities of these light sources. Light traveling within waveguide 110 into angular portion 100a may be reflected within waveguide 110 at a different angle than light traveling into angular portion 100b.

[0029] A characteristic of notch filters, e.g., thin film notch filters, is that the notch frequency that the filter blocks may exhibit a dependency on the angle of incident illumination. In other words, the wavelengths blocked by a notch filter may not be a constant function of the angle of incidence. Thus, the ability to filter a particular wavelength may degrade away from the central / design wavelength. The central wavelength of the notch of a notch filter is not as strictly constant, but rather depends on the angle of incidence. The central wavelength of the notch may be expressed in terms of the central wavelength when light is incident at a particular first angle of incidence. In at least some embodiments of the invention, this is compensated for by varying the wavelength of the light source as a function of angle.

[0030] The light source 140 may be controlled in such a manner as to pre-correct for variations in the angle of incidence of the notch filter used, so that light is effectively blocked by the notch filter in different portions of the waveguide 110. When encoding still or video images in the angular space of the light field 100, the angular portions of the light field 100 may be scanned continuously, such that the surface of the light field 100 is scanned using differently adjusted light source frequencies during successive scans. By continuous scanning, we mean herein a repetitive process in which color elements are rendered in the light field 100. Thus, the combination of monochromatic light sources used in combination with the notch filters described herein provides the benefit that no personal light information of the user is leaked, while at the same time, the user's ability to view his or her surroundings through the waveguide display is not impaired.

[0031] In the embodiment of FIG. 1, a waveguide 110 having a first inner surface 201 near the user's eye, and a second outer surface 202 opposite the waveguide 110, has a notch filter element 200 on the second outer surface 202 to prevent light from the light field 100 from being visible to anyone other than a user of the waveguide display.

[0032] The notch filter element 200 may be a multi-layer structure designed to function as a band-stop filter for each of the light sources 140, R, G, and B. In one example, the notch filter element 200 is formed as a sandwich of three different notch filters. As another example, a single layer includes multiple notches.

[0033] In Fig. 3a, a graph is presented of the wavelengths of light sources B, G and R, with the x-axis representing wavelength and the y-axis representing amplitude. As presented in the depiction, light source B has a wavelength λ1, light source G has a wavelength λ2 and light source R has a wavelength λ3, correspondingly. The light sources in this example are monochromatic, e.g. lasers.

[0034] In FIG. 3b, a graph of the transmission of the notch filter element 200 is presented for the light source of FIG. 3a. As shown in the graph, each stop band G', B', and R' of the filter has the same center wavelength as the light sources G, B, and R. In practice, the angle of incidence of the light inside the waveguide 110 to the notch filter 200 changes the filtering characteristics of the notch filter 200, and therefore tuning of the wavelengths of light entering the notch filter element 200 at different angles may be necessary. This may be done, for example, by modulating and / or tuning the wavelength of the light source 140, such that the wavelength of the light source is modulated and / or tuned based on the angle of incidence of the light at the waveguide 110 entering the notch filter element 200, or based on the angle of incidence into the waveguide 110, which may be related to each other. In some embodiments, the notch filter may have multiple stop bands corresponding to a single light source to cover different propagation directions inside the waveguide. For example, stop band G' may include multiple stop bands for light source G to cover multiple propagation directions. Multiple propagation directions of light emanating from a single light source may be due to, for example, diffraction into multiple diffraction orders. An alternative or additional solution may be to widen the stop bands R', G' and B' of the notch filter element 200, however this solution would reduce the overall transmittance of the notch filter element 200.

[0035] In the example of Figures 3a and 3b, three light sources and corresponding three stop bands are considered. In the more general case, the number and position of the stop bands correspond to the spectral characteristics of the light source or light sources used in the embodiment. For example, in an arrangement with two light sources with distinct wavelengths, a notch filter with two stop bands corresponding to two distinct wavelengths can be used.

[0036] Instructions on how to design optical notch filters can be found, for example, at the following web page: https: / / www.optilayer.com / notch-filters. The use of optical notch filters is also presented in European Patent Application No. 15812618.5.

[0037] Thus, overall, the wavelength of the light source 140, such as a laser, may be modulated during the creation of the light field 100 so that the light in the waveguide 110 is matched to the stop band of the notch of the notch filter element 200, regardless of its angle of incidence on the notch filter element 200 in the waveguide. Alternatively, the modulation may at least increase the efficiency of the notch filter element 200 in filtering the leaked light, even if not all of the leaked light is captured. Such modulation may include tuning the wavelength of the light source according to a mapping that maps the angular portion of the light field with wavelength tuning. The mapping may be determined experimentally, for example, in advance, since the behavior of the notch as a function of the angle of incidence is deterministic. The mapping may be stored in a memory of a computer, such as that illustrated in FIG. 4, configured to control the encoding of the image in the light field 100. Using an LED light source, a passive control mechanism may be used, for example, based on diffractive or refractive division of the LED output wavelength band, as described herein above. In the extreme case, a filter with a passband as wide as the stopband in the notch filter can be used to render the LED output monochromatic. Other source modulation and source filtering techniques can also be used to achieve the desired correspondence between propagation angle and (center) wavelength.

[0038] FIG. 4 illustrates an example device capable of supporting at least some embodiments of the present invention. An apparatus 400 is illustrated, which may include a control mechanism for operating an arrangement such as that illustrated in FIG. 1 or FIG. 2. A processor 410 is included in the apparatus 400, which may include, for example, a single or multi-core processor or a microcontroller, where a single-core processor includes one processing core and a multi-core processor includes multiple processing cores. The processor 410 may generally include a controller. The processor 410 may include multiple processors. The processor 410 may be a controller. The processing core may include, for example, a Cortex-A8 processing core manufactured by ARM Holdings, Inc., or a Steamroller processing core designed by Advanced Micro Devices Corporation. The processor 410 may include at least one Qualcomm Snapdragon and / or Intel Atom processor. The processor 410 may include at least one application-specific integrated circuit (ASIC). The processor 410 may comprise at least one field-programmable gate array (FPGA). The processor 410 may be a means for performing steps of the methods in the apparatus 400, such as generating, receiving, and transmitting. The processor 410 may be configured to perform operations at least in part by computer instructions.

[0039] The device 400 may comprise a memory 420. The memory 420 may include random access memory and / or permanent memory. The memory 420 may comprise at least one RAM chip. The memory 420 may include, for example, solid state memory, magnetic memory, optical memory, and / or holographic memory. The memory 420 may be at least partially accessible to the processor 410. The memory 420 may be at least partially comprised in the processor 410. The memory 420 may be a means for storing information. The memory 420 may comprise computer instructions that the processor 410 is configured to execute. The processor 410 and / or at least one of its processing cores may be considered to be configured to execute a particular operation when computer instructions configured to cause the processor 410 to perform said particular operation are stored in the memory 420 and the entire device 400 is configured to operate under the direction of the processor 410 using the computer instructions from the memory 420. The memory 420 may be at least partially comprised in the processor 410. The memory 420 may be, at least in part, external to the device 400, but accessible to the device 400. The memory 420 may store, for example, information defining the angular portions of the light field 100.

[0040] The apparatus 400 may comprise a transmitter 430. The apparatus 400 may comprise a receiver 440. The transmitter 430 and the receiver 440 may be configured to transmit and receive information, respectively, according to at least one cellular or non-cellular standard. The transmitter 430 may comprise multiple transmitters. The receiver 440 may comprise multiple receivers. The receiver 440 may be configured to receive an input image, and the transmitter 430 may be configured to output control commands to, for example, orient the mirror 130, if present, and the light source 140, according to the input image.

[0041] The device 400 may include a user interface (UI) 460. The UI 460 may include at least one of a display, a keyboard, a touch screen, a vibrator arranged to signal a user by vibrating the device 400, a speaker, and a microphone. A user may be able to operate the device 400 via the UI 460, for example, to set display parameters.

[0042] The processor 410 may be equipped with a transmitter arranged to output information from the processor 410 to other devices included in the device 400 via electrical leads within the device 400. Such a transmitter may, for example, include a serial bus transmitter arranged to output information via at least one electrical lead to the memory 420 for storage in the memory 420. Instead of a serial bus, the transmitter may include a parallel bus transmitter. Similarly, the processor 410 may be equipped with a receiver arranged to receive information at the processor 410 from other devices included in the device 400 via electrical leads within the device 400. Such a receiver may, for example, include a serial bus receiver arranged to receive information via at least one electrical lead from the receiver 440 for processing in the processor 410. Instead of a serial bus, the receiver may include a parallel bus receiver.

[0043] The device 400 may include additional devices not illustrated in FIG 4. In some embodiments, the device 400 does not include at least one of the devices described above. For example, the device 400 may not include the user interface 460.

[0044] The processor 410, memory 420, transmitter 430, receiver 440, NFC transceiver 450, UI 460 and / or user identification module 470 may be interconnected by electrical leads within device 400 in a number of different ways. For example, each of the aforementioned devices may be individually connected to a master bus within device 400, allowing the devices to exchange information. However, as will be appreciated by those skilled in the art, this is only one example and depending on the embodiment, various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0045] 5 is a flow graph of a method according to at least some embodiments of the present invention. The illustrated method steps may be in a waveguide-based display, a light guide arrangement in or for a waveguide-based display, or a control mechanism configured to control its functionality when incorporated therein.

[0046] Step 510 includes using an optical system to generate a configurable image encoded in a light field. Step 520 includes receiving light from the light field into at least one light guide and transmitting the light to a plurality of locations in the light guide for emission to create a waveguide-based display. Step 530 specifies that the optical system includes three light sources having wavelengths λ1, λ2, and λ3, respectively, and the light guide has notch filter elements having stop bands of wavelengths λ1', λ2', and λ3' disposed on an outer surface of the light guide to prevent leakage of light from the light field. As explained above, λ1 and λ1' may not be equal in the general case. Instead, a notch filter having a stop band of λ1' may be designed to block light having wavelength λ1 incident at a particular angle. For example, the stop band of λ1' may correspond to light having wavelength λ1 incident at an angle corresponding to a center pixel. The wavelength λ1 of the light source can be adjusted so that the stop band λ1' also blocks that light when illuminating the pixel at a different angle of incidence. The same applies to each light source and the corresponding stop band of the notch filter, i.e., the stop bands λ2', λ3' corresponding to the light sources with wavelengths λ2 and λ3 in step 530 of FIG. 5, respectively.

[0047] It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures, process steps, or materials disclosed herein, but rather to equivalents thereof that would be recognized by one of ordinary skill in the relevant arts. It is also to be understood that the terminology employed herein is used only for the purpose of describing particular embodiments, and is not intended to be limiting.

[0048] Reference throughout this specification to an embodiment or examples means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. When a numerical value is referred to using a term, such as about or substantially, the exact numerical value is also disclosed.

[0049] As used herein, a plurality of articles, structural elements, components, and / or materials may be presented in a common enumeration for convenience. However, these enumerations should be construed as if each element of the enumeration were individually identified as a separate and unique element. Thus, any individual element of such enumeration should not be construed as being effectively equivalent to other elements of the same enumeration solely based on their presentation in a common group, unless indicated to the contrary. In addition, various embodiments and examples of the invention may be referred to herein, along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives should not be construed as being effectively equivalent to each other, but should be considered as separate and independent manifestations of the invention.

[0050] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the foregoing description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the present invention. However, one of ordinary skill in the relevant art will recognize that the present invention may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the present invention.

[0051] While the foregoing examples illustrate the principles of the present invention in one or more specific applications, it will be apparent to those skilled in the art that numerous modifications in the embodiments, usage and details may be made without the exercise of inventive skill and without departing from the principles and concepts of the present invention. Accordingly, it is not intended that the present invention be limited except as by the claims set forth below.

[0052] The verbs "comprise" and "include" are used in this document as open limitations that do not exclude or require the presence of further unrecited features. Features recited in the dependent claims are mutually freely combinable, unless expressly stated otherwise. Furthermore, it is to be understood that the use of "a" or "an", i.e. the singular, throughout this document does not exclude a plurality. [Industrial Applicability]

[0053] At least some embodiments of the present invention find industrial application in improving waveguide displays. [Explanation of symbols]

[0054] LED Light Emitting Diode MEME Microelectromechanical 100 Light Field 102 Light Guide 104 light 110 Waveguide 112a, 112 element 114 Directed Light 120 eyes 130 Mirror 140 light source 100a, 100b Angular portion of light field 100 400~460 Structure of the equipment in Figure 4 410-430 Steps of the method of FIG. 200 Notch filter element 201 First (inner) surface of the waveguide 202 second (outer) surface of the waveguide R is a light source having a wavelength λ1 G Light source with wavelength λ2 B Light source with wavelength λ3 R' is the stopband of the notch filter with wavelength λ1 G' is the stopband of the notch filter with wavelength λ2 B' is the stopband of the notch filter with wavelength λ3 λ 1~3Light source and stopband central wavelength

Claims

1. 1. An optical waveguide arrangement, comprising: an optical system configured to generate a configurable image encoded in the light field; at least one light guide arranged to receive light from the light field and to transmit the light to a plurality of locations in the light guide for emission, creating a waveguide-based display; and Equipped with The optical system has a wavelength λ １ a light source having The light guide is disposed on an outer surface of the light guide to prevent light from escaping from the light field, and the wavelength λ １ a notch filter element having a stop band of wavelength λ １ The stop band of wavelength λ ′ is incident on the notch filter element at a first angle of incidence. １ Filters the light of the optical waveguide arrangement is configured to modulate the wavelength of the light source based on an angle of incidence of the light in the waveguide to the notch filter element and / or based on an angle of incidence of the light into the waveguide. Optical waveguide arrangement.

2. The optical system has a wavelength λ ２ and wherein the notch filter element has a wavelength λ ２ ' and a stop band at wavelength λ ２ The stop band of λ ′ is incident on the notch filter element at the first angle of incidence or the second angle of incidence. ２ 10. The optical waveguide arrangement of claim 1, wherein the optical waveguide arrangement filters light of

3. The optical system has a wavelength λ ３ and wherein the notch filter element has a wavelength λ ３ ' and has a stop band of wavelength λ ３ the stop band of λ′ is incident on the notch filter element at the first angle of incidence, the second angle of incidence, or the third angle of incidence; ３ 3. The optical waveguide arrangement of claim 2, wherein the optical waveguide arrangement filters light of

4. 2. The light guide arrangement of claim 1, wherein said modulating comprises adjusting the wavelength of said light source according to a mapping of an angular portion of a light field to a stop band of said notch filter.

5. 4. The optical waveguide arrangement of claim 2 or claim 3, wherein the light source comprises a laser light source.

6. 4. The light guide arrangement of claim 2 or claim 3, wherein the light source comprises a light emitting diode light source.

7. 3. The light guide arrangement of claim 1 or claim 2, wherein the light guide arrangement is configured to provide a display as a head mounted display.

8. 4. An optical waveguide arrangement according to claim 2 or claim 3, wherein the stop band of the notch filter has a width of at most 2 nanometers.

9. 4. The optical waveguide arrangement of claim 2, wherein the notch filter is a reflective notch filter.

10. 10. The optical waveguide arrangement of claim 1, wherein the stop band of the notch filter has a width of at most 2 nanometers.

11. 2. The optical waveguide arrangement of claim 1, wherein the notch filter is a reflective notch filter.

12. 3. The light guide arrangement of claim 1 or claim 2, wherein the notch filter element is configured to have a plurality of stop bands for each light source in the light guide arrangement.

13. generating a configurable image encoded in a light field using an optical system; receiving light from the light field into at least one light guide and transmitting the light to a plurality of locations in the light guide for emission to create a waveguide-based display; 1. A method comprising manipulating an optical waveguide arrangement, comprising: The optical system has a wavelength λ １ a light source having The light guide is disposed on an outer surface of the light guide to prevent light from escaping from the light field, and the wavelength λ １ ', and a notch filter element having a stop band of wavelength λ １ The stop band of wavelength λ ′ is incident on the notch filter element at a first angle of incidence. １ Filters the light of the method further comprising modulating the wavelength of the light source based on an angle of incidence of the light in the waveguide to the notch filter element and / or based on an angle of incidence of the light into the waveguide. method.

14. The optical system has a wavelength λ ２ and wherein the notch filter element has a wavelength λ ２ ' and a stop band at wavelength λ ２ The stop band of λ ′ is incident on the notch filter element at the first angle of incidence or the second angle of incidence. ２ 14. The method of claim 13, further comprising filtering light.

15. The optical system has a wavelength λ ３ and wherein the notch filter element has a wavelength λ ３ ' and has a stop band of wavelength λ ３ the stop band of λ′ is incident on the notch filter element at the first angle of incidence, the second angle of incidence, or the third angle of incidence; ３ 15. The method of claim 14, further comprising filtering light of

16. 14. The method of claim 13, wherein the modulating comprises mapping angular portions of the light field with wavelength tuning and tuning the wavelength of the light source according to the mapping.

17. 16. The method of claim 14 or claim 15, wherein the light source comprises a laser light source.

18. 16. The method of claim 14 or claim 15, wherein the light source comprises a light emitting diode light source.

19. The method of claim 13 or claim 14, wherein the operating comprises providing the display as a head-mounted display.

20. When executed by at least one processor, the device performs at least: generating a configurable image encoded in a light field using an optical system; transmitting the light from the light field to at least one light guide arranged to receive the light and to transmit the light to a plurality of locations in the light guide for emission, creating a waveguide-based display; A non-transitory computer-readable medium having stored thereon a set of computer-readable instructions, comprising: The optical system has a wavelength λ １ a light source having The light guide is disposed on an outer surface of the light guide to prevent light from escaping from the light field, and the wavelength λ １ ', and a notch filter element having a stop band of wavelength λ １ The stop band of wavelength λ ′ is incident on the notch filter element at a first angle of incidence. １ Filters the light of the computer-readable instructions are further configured to cause the device to modulate the wavelength of the light source based on an angle of incidence of the light in the waveguide to the notch filter element and / or based on an angle of incidence of the light into the waveguide. Non-transitory computer-readable medium.

21. A computer program configured to cause the computer to carry out the method of claim 13 or 14.

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