Waveguide combiner

Abstract

An optical waveguide combiner having an output coupler that includes an array of embedded partially reflective dielectric mirrors that expand and couple a virtual (optionally, color) image generated by a laser display engine into a user EMB, where the image is transmitted to the user EMB. The dielectric mirror is configured to have: a wavelength band for each laser emission band of the laser display engine, the wavelength band including wavelengths of light in the laser emission band and in a wavelength range in which the laser emission band is expected to drift; presenting a reflectivity angle range of the first reflectivity; exhibiting a transmittance angular range of a second reflectance less than the first reflectance; and a perspective angle transmittance range having a high transmittance for natural light incident on the facet.

Description

[0001] This application is a divisional application of the invention patent application with the application date of February 22, 2021, application number 202180013816.6* (international stage application number PCT / IL2021 / 050206), and invention name “Mixed Reality Combiner”.

[0002] Related applications

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 980,469, filed February 24, 2020, and U.S. Provisional Application No. 63 / 001,567, filed March 30, 2020, under 35 U.S.C. § 119(e). Technical Field

[0004] Embodiments of the present disclosure relate to an optical waveguide system configured to receive an image from a laser display engine at a relatively small input aperture and deliver the image to exit the waveguide at an extended output coupling region to fill an enlarged eye motion box for viewing by a user. Background Art

[0005] The proliferation of head mounted displays (HMDs) and smart glasses used to provide users with various new flavors of reality—any of augmented reality (AR), mixed reality (MR), and parallel reality—superimposes computer-generated “virtual images” on a “real image” of the real environment in the user’s field of view (FOV) as seen by the user. The virtual images may, for example, provide the user with informational material and / or entertainment related to the real image, tasks performed by the user, and / or explicit or implicit user requests. An image presented to a user that includes both real and virtual images may be referred to as an extended reality (XR) image, and any of the various hardware configured to provide an XR image to a user may be collectively referred to as an XR display.

[0006] In the optical system of an XR display, a computer-controlled display engine, such as a liquid crystal silicon (LCos), organic light emitting diode (OLED), or laser beam scanning (LBS) microdisplay, provides a virtual image. An optical element called a combiner receives the virtual image provided by the display engine and overlays it on a real image to provide an XR image to the user. The combiner is transparent to ambient light, and the user views the real environment through the combiner.

[0007] Typically, the virtual image provided by the display engine is relatively small, having a feature size of less than or equal to about 5 mm. The combiner receives the small virtual image with a relatively small input aperture and transmits the image to an output coupler, which outputs the virtual image through the combiner's exit aperture and into the eye motion box (EMB). When the user's eye is located in the EMB, the virtual image passes through the user's aperture and reaches the user's retina, appearing in the XR image as a feature of the actual image seen by the user through the combiner. In order to fill the EMB so that the user can comfortably see the virtual image without unduly bothering to align their eyes with the combiner, the combiner is typically constructed with a relatively large, expanded aperture, through which the combiner transmits many copies of the virtual image into the EMB.

[0008] The optical system of a practical XR display typically needs to meet a complex combination of ergonomic, technical, and economic constraints. The optical system is advantageously constructed to have a comfortably large EMB, is advantageously small, light, and energy-efficient, and provides a clear virtual image without overly obtrusive artifacts such as image ghosting. Summary of the Invention

[0009] One aspect of embodiments of the present disclosure relates to providing an optical waveguide combiner having an output coupler comprising an array of embedded dielectric partial reflectors, hereinafter also referred to as facets, for extending and coupling a virtual, optionally colored, image generated by a laser display engine into a user optical beamforming (EMB). The facets are configured to reflect incident light within a first range of incident angles into the user optical beamforming (EMB) with relatively high transmittance for light in a wavelength band provided by a laser used by the engine to generate the virtual image. Within a second range of incident angles, different from the first range, the facets are configured to have relatively low reflectivity and transmit light within a substantially identical laser wavelength band with relatively high transmittance. The transmittance and reflectance exhibit relatively low variability within the first and second angular ranges, as well as within the wavelength range spanned by the laser wavelength band. The facets are configured to have substantially achromatic transmission for visible light from the environment (also referred to as natural light). Optionally, the display engine comprises at least one laser that provides light in a red, green, and blue (RGB) bandwidth to the display engine, and the display engine processes the light to generate a virtual RGB color image. In an embodiment, the combiner introduces a color virtual image into the EMB with relatively high RGB image resolution and relatively low doping of image artifacts.

[0010] In an embodiment, a waveguide combiner includes a waveguide having a first parallel total internal reflection (TIR) ​​surface and a second parallel total internal reflection surface. Light from a display engine enters the waveguide and is repeatedly reflected from and back and forth between the TIR surfaces to propagate along the waveguide in a reduced waveguide FOV (wFOV) to reach and impinge on a facet. In an embodiment, the facets are evenly spaced and parallel and tilted at an angle measured between the normal to the TIR surface and the normal to the facet. The component of a light ray in the wFOV that is parallel to the TIR normal reverses direction each time the ray reflects off the first TIR surface and each time the light reflects off the second TIR surface. Light rays in the wFOV that have undergone an even or odd number of reflections (counted from any first reflection) before impinging on a given facet are incident on a given facet at an angle of incidence in the first range of angles of incidence or the second range of angles of incidence, respectively. According to an embodiment of the present disclosure, light rays incident on the facet only within one of a first range of incident angles and a second range of incident angles are selected for outcoupling from the waveguide and into the EMB to provide a virtual image generated by a display engine to a user.

[0011] For ease of presentation, the range of incident angles from which rays in the wFOV are selected to provide a virtual image may be referred to as the "image incidence range." The wFOV, when directed by TIR reflection in the waveguide to include rays propagating along angular directions within the image incidence range, may be referred to as the "image wFOV." The non-selected range of incident angles may be referred to as the "conjugate incidence range," and the wFOV, when directed by TIR reflection in the waveguide to include rays propagating along angular directions within the conjugate incidence range, may be referred to as the "conjugate wFOV."

[0012] According to an embodiment, the inclination angle of the facet is determined to provide a favorable angular separation between the image incidence range and the conjugate incidence range. The facet is configured to have a reflectivity angular range, a transmittance angular range, and a facet wavelength band. For light with a wavelength in the facet wavelength band and an incident angle in the reflectivity angular range that is incident on the facet, the facet exhibits a relatively high reflectivity and a relatively low variation with changes in wavelength and incident angle. Similarly, for light with a wavelength in the facet wavelength band and an incident angle in the transmittance angular range that is incident on the facet, the facet exhibits a relatively low reflectivity and a corresponding high transmittance, and a relatively low variation with changes in wavelength and incident angle. The facet wavelength band spans the following wavelength range: the wavelength range includes the laser emission bandwidth of the laser that provides light processed by the display engine to generate the virtual image and the wavelength range in which the expected laser emission bandwidth may vary, where the reason for the variation in the laser emission bandwidth is, for example, due to drift caused by operating conditions and / or manufacturing tolerances.

[0013] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Non-limiting examples of embodiments of the present disclosure are described below with reference to the figures attached hereto listed following this paragraph. Identical features appearing in more than one figure may be labeled with the same reference numeral in the multiple figures in which they appear. Reference numerals indicating icons representing given features of embodiments of the present disclosure in the figures may be used to reference given features. The dimensions of the features shown in the figures are selected for convenience and clarity of presentation and are not necessarily shown to scale.

[0015] Figure 1ASchematically illustrates a waveguide combiner according to an embodiment of the present disclosure, comprising a waveguide having an output coupler comprising an array of facets that expand an input aperture of the combiner in one direction to provide an expanded output through which the combiner transmits a virtual image received through the input aperture into an EMB;

[0016] Figure 1B Schematic diagram showing the reflection of light from the laser display engine into the user EMB according to an embodiment of the present disclosure Figure 1A A cross section of the combiner shown in ;

[0017] Figure 1C Schematically shows an embodiment according to the present disclosure Figure 1B An enlarged portion of the combiner shown in FIG, where light from the laser display engine enters the combiner;

[0018] Figure 1D Schematically shows an embodiment according to the present disclosure Figure 1B An enlarged portion of the combiner shown in FIG, where light from the laser display engine leaves the combiner and enters the EMB;

[0019] Figure 1E FIG. 1 shows a laser display engine as light from the laser display engine according to an embodiment of the present disclosure. Figure 1A and Figure 1C Schematic diagram of the reflectivity as a function of the incident angle on the facet shown in and the reflectivity of the facet for natural light;

[0020] Figure 1F Schematically shows an embodiment according to the present disclosure Figure 1A and Figure 1B Selectable lasing bandwidths for the lasers in the display engine shown in and matching facet wavelength bands for the facets shown in the figure;

[0021] Figure 1G The facet wavelength band for blue light according to an embodiment of the present disclosure is shown. Figure 1A and Figure 1B A graph of the reflectivity of the facet shown in as a function of wavelength;

[0022] Figure 2A Schematically shows a similar embodiment according to the present disclosure Figure 1A A cross section of a waveguide combiner of the combiner shown in , the waveguide combiner including facets tilted at a moderate angle that reflect light from the laser display engine into the user EMB;

[0023] Figure 2BThe embodiment according to the present disclosure is shown as Figure 2A Schematic graph of reflectivity as a function of the angle of incidence of light on the facet shown in ;

[0024] Figure 3A Schematically shows a similar embodiment according to the present disclosure Figure 1A A cross section of a waveguide combiner of the combiner shown in , the waveguide combiner including facets tilted at a relatively large tilt angle that reflect light from the laser display engine into the user EMB;

[0025] Figure 3B The embodiment according to the present disclosure is shown as Figure 2A Schematic graph of reflectivity as a function of the angle of incidence of light on the facet shown in ;

[0026] Figure 4 Schematically shown is a perspective view of a waveguide combiner including a waveguide system providing two-dimensional aperture expansion according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] In the discussion, unless otherwise stated, adjectives such as "substantially" and "about" that modify the conditions or relationship characteristics of one or more features of the embodiments of the present disclosure should be understood to mean that the condition or characteristic is defined to be within an acceptable tolerance for the operation of the embodiment for the application for which the embodiment is intended. In any case, the general terms in the present disclosure are explained by reference to an example instance or a list of example instances, the one or more examples referenced are non-limiting example instances of the general terms, and the general terms are not intended to be limited to the one or more specific example instances referenced. Unless otherwise stated, the word "or" in the specification and claims is considered to be an inclusive "or" rather than an exclusive or, and indicates any combination of at least one or more of the items to which it is connected.

[0028] Figure 1A Schematically illustrated is a waveguide combiner 20 according to an embodiment of the present disclosure, the waveguide combiner 20 optionally comprising a waveguide 30 having two relatively large parallel facet surfaces 31 and 32, an edge surface 34, and an output coupler 40 comprising an array of parallel, optionally equally spaced facets 42 embedded in the waveguide. For ease of presentation, the positions of features of the waveguide combiner 20 may be referenced relative to the x-, y-, and z-axes of a Cartesian coordinate system 100.

[0029] Assume that facet surfaces 31 and 32, also known as total internal reflecting (TIR) ​​surfaces 31 and 32, are arbitrarily parallel to the xy plane of coordinate system 100. Facet 42 is parallel to the x-axis and rotated about the x-axis by an inclination angle β in a counterclockwise direction as viewed along the x-axis toward the yz plane. The input aperture of waveguide 30, schematically represented by dashed rectangle 35, is optionally parallel to the xz plane, and the output coupling region of the waveguide, schematically represented by dashed rectangle 36, is optionally located on facet surface 32. Optionally, waveguide combiner 20 includes a prismatic input coupler 50 for coupling light from a virtual image generated by display engine 70 into waveguide 30 via input aperture 35. Output coupler 40 operates in accordance with embodiments of the present disclosure to expand input aperture 35 in the y-direction and reflect light from the virtual image received through input aperture 35 and propagating in waveguide 30 to the output coupler via expanded output coupling region 36 into EMB 60 for viewing by user 102. In subsequent figures, user 102 may be represented by only the user's eyes. As an example, in FIG1 , waveguide combiner 20 is shown generating a virtual image schematically represented by dashed rectangle 72. Natural light from the environment viewed by user 102 through waveguide 30 is schematically represented by block arrow 74.

[0030] Figure 1B The waveguide combiner 20 according to an embodiment of the present disclosure is shown along Figure 1A Schematic cross section of the plane AA indicated in FIG and the propagation of light from the virtual image 72 in the waveguide 30 to form the wFOV supported by the combiner.

[0031] Figure 1B Schematically illustrates a virtual image 72 in the dFOV from a display engine 70 according to an embodiment of the present disclosure ( Figure 1A ) of light, which illuminates the face surface 51 of the input coupler 50, which couples the light into the waveguide 30 via the input aperture 35. For ease of observation and reference, Figure 1C The input coupler 50, the input aperture 35 and the portion of the waveguide 30 located in the circle 202 are shown in FIG. In plane AA, the dFOV is represented by the positive angle α′+ and the negative angle α′ - Definition, which defines the angular range of dFOV Φ'=(α' + -α' - )=(|α' + |+|α' - |). Angle α' + and α' - are the rays 81 and 82 that define the angular range of the dFOV ( Figure 1C) with the angle of the chief ray of the dFOV represented by arrow 83. Rays 81 and 82 and their corresponding reflections and refractions in the waveguide combiner 20 are represented by solid and dashed lines, respectively, and may be referred to as positive and negative boundary rays.

[0032] With respect to the principal ray 83, if the plane AA is from the virtual image 72 ( Figure 1A ) relative to Figure 1B The angle of the ray is considered positive or negative if the principal ray in the following figures rotates clockwise or counterclockwise, respectively. Assume that the principal ray 83 is perpendicular to the face surface 51 of the input coupler 50, and assume that the refractive index of the materials made of the input coupler and the waveguide 30 with respect to air is equal to the same refractive index n g .

[0033] When entering the input coupler 50, Figure 1C As more clearly shown by the magnified region 202 of the input coupler in FIG, the refraction of light reduces the angles α′+ and α′− and the accompanying angular range Φ′ of the dFOV by a factor of the refractive index n. g In the waveguide combiner 20, the reduced angles corresponding to α'+ and α'- are denoted by α+ and α-, respectively, and the reduced angular range characterizing the field of view wFOV of the light from the display engine 70 after entering the waveguide combiner 20 is denoted by Φ. The angles α+ and α- are the angles that the boundary rays 81 and 82 form with the principal ray 83 in the waveguide 30 after being refracted and entering the input coupler 50. The boundary rays define the wFOV in the waveguide combiner 20, and the angle defines the angular range of the wFOV Φ = (|α + |+|α - |). Field of view wFOV is Figure 1B and Figure 1C and shown shaded in subsequent figures.

[0034] Note that α'+ and α'- are defined as positive and negative angles, respectively, and that upon entering input coupler 50, the corresponding angles α+ and α- are also defined as positive and negative angles, respectively. However, with each reflection from TIR surface 31 or 32, boundary rays 81 and 82 reverse their respective rotations relative to principal ray 83. As a result, boundary rays 81 and 82 are rotated clockwise by angles α+ and α-, respectively, relative to principal ray 83, upon reflection from facet surface 31, according to the adopted convention of clockwise rotation being positive and counterclockwise rotation being negative. However, upon reflection from TIR facet surface 32, boundary rays 81 and 82 are rotated counterclockwise by angles -α+ and -α-, respectively, relative to principal ray 83.

[0035] In the waveguide 30, as Figure 1BAs shown schematically, the light in the wFOV is totally reflected by the TIR surface 31 and the TIR surface 32 and reflects back and forth between the TIR surface 31 and the TIR surface 32 until it reaches and is incident on the facet 42 of the output coupler 40. At each reflection, the light in the wFOV is reflected along the waveguide normal “n w ” components (not shown) are reversed in direction. As a result, light rays in the wFOV have a z component in the positive z direction after being reflected from face surface 31 and can be considered as “downward” rays traveling downward from face surface 31 toward face surface 32 in the figure. When downward rays are included, the wFOV is oriented to face downward, in the positive z direction. Similarly, light rays have a z component in the negative z direction after being reflected from and reflecting off face surface 32 and can be considered as “upward” rays traveling upward from face surface 32 toward face surface 31. When facing downward, the wFOV can be distinguished and referred to as wFOV-Down and in Figure 1B and is labeled as wFOV-D in subsequent figures. Similarly, when facing upwards, the wFOV can be distinguished and is referred to as wFOV-Up and in Figure 1B and is labeled as wFOV-U in subsequent figures. The label "wFOV" refers collectively to both wFOV-U and FOV-D.

[0036] Upon reaching the output coupler 40, the upward rays in wFOV-U are directed with respect to the facet normal “n f The first range of incident angles (hereinafter also referred to as the upper range) of incident light in wFOV-U is incident on the facet 42, and the downward light rays in wFOV-D are incident on the facet 42 at a second range of incident angles (hereinafter also referred to as the lower range). According to an embodiment of the present disclosure, light rays in one of wFOV-U or wFOV-D are selected to be reflected by the facet 42 out of the waveguide 30, pass through the outcoupling region 36, and enter the EMB 60 so that the user views a virtual image generated by the display engine 70, such as virtual image 72 ( Figure 1A ). For light waves in the selected wFOV-U or wFOV-D, facet 42 is configured to have relatively enhanced reflectivity for the corresponding upper or lower range of incidence angles. For light waves in the unselected wFOV, facet 42 is configured to have relatively enhanced transmittance. The selected wFOV can be referred to as the image wFOV, and the unselected wFOV can be referred to as the conjugate wFOV.

[0037] As an example, in the waveguide 30, the facets 42 are oriented at a relatively small tilt angle β, and the light rays in wFOV-U and wFOV-D are incident on the facets from opposite sides of the facets. According to an embodiment of the present disclosure, wFOV-U is selected as the image wFOV, and the light rays in wFOV-U are selected to be reflected out of the waveguide 30 through the outcoupling region 36 to provide the output field of view O-FOV in the EMB 60 for viewing the virtual image generated by the display engine 70. For ease of presentation and reference, Figure 1B The area indicated by circle 204 is in Figure 1D Shown enlarged in the figure.

[0038] Figure 1D 2 shows an enlarged portion of the waveguide 30, including the facets 42, the EMB 60, and the O-FOV as seen by the user 102, as well as angles relevant to embodiments of the present disclosure and a virtual image as seen by the user, such as the virtual image 72 provided by the display engine 70. The figure schematically shows light from the upwardly directed positive boundary ray 81 and the negative boundary ray 82 being output by the output coupler 40 ( Figure 2A ) is reflected into EMB 60 as positive boundary output ray 91 and negative boundary output ray 92. Rays 91 and 92 define the output field of view O-FOV seen by user 102. As an example, assume that O-FOV has the same field of view dFOV ( Figure 1C ) the same angular range Φ', the field of view dFOV includes light received by the prism input coupler 50 and introduced by the input coupler into the waveguide 30 via the input aperture 35. The boundary output rays 91 and 92 in the waveguide 30 make angles α+ and α-, respectively, with the output chief ray 93 of the O-FOV reflected from the chief ray 83 by the facet 42. Optionally, the output rays 91 and 92 are also aligned with the normals n of the facet surfaces 31 and 32. w Boundary output rays 91 and 92 are refracted upon entering EMB 60 to form angles α'+ and α'- with the light in output chief ray 93, respectively.

[0039] The negative boundary ray 82 incident on the facet 42 is relative to the normal n W At an angle γ-, the facet reflects light from the negative boundary ray 82 as a negative boundary output ray 92. Similarly, the positive boundary ray 81 incident on the facet 42 is reflected relative to the normal n W At an angle γ+, where the facet reflects light from the positive boundary ray 81 as a positive boundary output ray 91. The angles γ- and γ+ are functions of the tilt angle β and the angles α- and α+, respectively, and can be written as:

[0040] 1)γ - =(2β-α- );as well as

[0041] 2)γ + =(2β-α + ),

[0042] where, note that, by definition, the "counterclockwise" angle α - has a negative value, and the "clockwise" angle α + has a positive value. The relationship provided by expressions 1) and 2) is valid for any ray in the wFOV, and if α represents the angle that any ray in the wFOV makes with the chief ray 83, then for any α this angle γ can be written as,

[0043] 3)γ=(2β-α).

[0044] Therefore, the light in wFOV-U is directed relative to the facet normal n f The incident angle φ u The incident angle φ u It is given by the following expression,

[0045] 4)φ u =(γ-β)=(α-α),

[0046] and the associated upper range of the incident angle selected as the image incidence range includes (β-α + ) and (β-α - ) and can be given by the following expression,

[0047] 5) Similarly, the light in wFOV-D is emitted relative to the normal n. f The incident angle φ d The incident angle φ d It can be given by the following expression,

[0048] 6)φ d =(γ+β)=(3β-α),

[0049] and the associated Down-Rang chosen as the conjugate incidence range can be written as,

[0050] 7)

[0051] According to an embodiment of the present disclosure, to mitigate the appearance of artifacts associated with virtual images in EMB 60, it is advantageous for all rays in wFOV-U to be incident on the same side of facet 42 and for all rays in wFOV-D to be incident on the same side of facet 42. The side on which the rays in wFOV-U are incident on facet 42 may be the same side or a different side of the facet on which the rays in wFOV-D are incident, depending on the embodiment.

[0052] As an example, the waveguide combiner 20 and the field of view wFOV are configured so that all rays in wFOV-U are incident on the side of the facet 42 facing the facet surface 32, and all rays in wFOV-D are incident on the opposite side of the facet, that is, the side facing the facet surface 31. To provide for incidence on opposite sides, the waveguide combiner 20 is configured so that for any ray in wFOV supported by the waveguide combiner, the complementary angle γ is greater than the tilt angle β of the facet 42. Symbolically,

[0053] 8)(90-γ)>β,

[0054] When replacing γ and noting that α+>α-, the above formula requires that the tilt angle β in the combiner 20 satisfies a first constraint given by the following expression according to an embodiment of the present disclosure,

[0055] 9)β<(30°+α - / 3).

[0056] In order to provide total internal reflection of light in the wFOV from the facet surfaces 31 and 32, it is required that for any light ray in the wFOV, the angle γ is greater than the critical angle θ of the waveguide 30 c , which leads to the second constraint that the tilt angle β in the combiner 20 satisfies:

[0057] 10)

[0058] The constraints given by Expression 9) and Expression 10) can be combined into a single expression that provides a limit on the tilt angle β of the combiner 20,

[0059] 11)(θ c +α + ) / 2<β<(30°+α - / 3).

[0060] As an example, suppose |α + |=|α - |=Φ / 2, then the constraint on the tilt angle β in the combiner 20 can be expressed as a function of the field of view wFOV,

[0061] 12)(θ c+Φ / 2) / 2<β<(30°+Φ / 6).

[0062] Expressed as the angular range Φ′ of the output field of view O-FOV seen by the user 102 in the EMB 60, the constraint on β can be approximated by Expression 11,

[0063] 13)(θ c +Φ′ / 2n g ) / 2<β<(30°+Φ′ / 6n g ),

[0064] where n g is the refractive index of the material forming the waveguide combiner 20 .

[0065] As a numerical example, assume that for green light n with a wavelength of about 550 nm g is equal to 1.51, the absolute values ​​|α+| and |α-| are both equal to about 13°, and the diagonal extent of Φ′ is about 30°, and the aspect ratio is 16:9. For β equal to about 26°, the upper range reflectivity angle range of the incident angle advantageously extends from about 17° to 35°, and the lower range transmittance angle range advantageously extends from about 66° to about 84°. Optionally, the angular width of the reflectivity angle range can be greater than or equal to about 15° or greater than or equal to about 20°. Optionally, the lower limit of the reflectivity angle range can be about 2°, about 25°, or about 50°. Optionally, the lower limit of the transmittance angle range can be about 2°, about 50°, or about 60°. Optionally, the angular width of the transmittance angle range can be greater than or equal to about 15° or greater than or equal to about 30°. Advantageously, the reflectivity of light in the upper range is between about 9% and about 11%, and optionally greater than about 10%, and the reflectivity of light in the lower range is less than about 1.5%, and optionally less than about 1%. Ambient natural light 74 ( Figure 1A The angular "see-through" range of the lens advantageously extends from about 5° to about 45° and exhibits an achromatic transmittance substantially greater than or equal to about 85%. Preferably, the angular width of the see-through angle transmittance range may be greater than or equal to 30° or greater than or equal to 40°. Alternatively, the lower limit of the see-through angle transmittance range may be 5°, 15°, or 40°.

[0066] Figure 1EA graph 210 is shown of the reflectivity of a facet 42 that can be manufactured to substantially conform to the numerical specifications discussed above. The graph includes a reflectivity curve 212 that gives the reflectivity of the facet 42 in the waveguide 30 as a function of the angle of incidence of light on the facet. The ordinate along the graph 210 shows the reflectivity expressed as a percentage, and the abscissa shows the angle of incidence of light on the facet 42. The upper range of angles of incidence selected as the image wFOV and the reflectivity angular range is schematically represented by the shaded area 218. The lower range of angles of incidence selected as the transmittance angular range and the conjugate wFOV is schematically represented by the shaded area 216. The dashed cap function 214 indicates the reflectivity of the facet to natural light 74 ( Figure 1A )'s "perspective" angle range.

[0067] Assuming that the display engine 70 includes a laser diode (LD) that provides R light, G light, and B light, and the display engine processes the provided R light, G light, and B light to generate a virtual image, the facet 42 is designed so that for each R, G, and B laser bandwidth of the expected LD emission laser, the reflectivity of the facet is relatively constant as a function of the wavelength of the upper and lower ranges of the incident angle. Optionally, the change in the reflectivity of the facet is less than 5% with respect to the wavelength in the corresponding R, G, and B facet wavelength bands. In one embodiment, the change is less than 2%. Alternatively, in another embodiment, the change in the reflectivity of the facet for the incident angle within the reflectivity angle range and the wavelength in the facet wavelength band is less than about 2.5% of the average reflectivity.

[0068] LDs typically emit laser light at wavelengths in a relatively narrow wavelength band between 1 nm and 2 nm (nanometers) FWHM (full width half maximum). However, the LD lasing bandwidth may shift by as much as 0.1 nm to 0.35 nm for each degree Celsius (°C) change in the LD operating temperature, and the operating temperature may easily vary by as much as 20°C. In addition, manufacturing tolerances may allow the center lasing wavelength of the same type of LD to vary by as much as 5 nm. According to an embodiment, the facets 42 are advantageously configured to have a facet wavelength band for each of the R light, G light, and B light generated by the LD for an upper range of incident angles and a lower range of incident angles equal to or greater than approximately 20 nm. Advantageously, for each facet, the wavelength band reflectivity variation for the wavelengths within the band is less than 3% of the average reflectivity to provide a color gamut chromaticity difference radius "ΔCG" in the CIE 1931xy color space of less than or equal to approximately 0.02.

[0069] As an example, Figure 1FThe laser emission bandwidths 120R, 120G and 120B of the R, G and B laser emission bandwidths of the LD in the display engine 70 according to an embodiment of the present disclosure and the corresponding facet wavelength bands 121RW, 121GW, 121BW of the facet 42 are schematically shown, wherein the bandwidth of the facet wavelength band for the laser emission band in at least one laser emission band is greater than or equal to three times the bandwidth of the laser emission band or greater than or equal to four times the bandwidth of the laser emission band. Figure 1G Graph 230 shows curve 232, which plots the reflectivity of facet 42 as a function of wavelength for the blue wavelength range in the visible spectrum. The average reflectivity for incident angles within the transmittance angular range and wavelengths in the facet wavelength band is between about 0.5% and about 5%. In inset 234, a portion of curve 232 is magnified and labeled to illustrate the region of the curve centered at a blue wavelength of about 450 nm between about 445 nm and about 455 nm, which curve represents the reflectivity as a function of wavelength in facet wavelength band 121BW. For wavelengths in facet wavelength band 121BW, the reflectivity of facet 42 is equal to about 4.8%, and the reflectivity varies by less than about 5% for wavelengths in the wavelength band.

[0070] With targeted Figure 1E The incident angle perspective range, upper and lower range reflectivity, and Figure 1F The facets 42 of the R, G, and B facet wavelength bands shown may include partially reflective dielectric mirrors. Partially reflective dielectric mirrors can be made by depositing a partially reflective coating on the surface of a pre-formed prism and bonding the prisms together. The prisms can be made by grinding and polishing a silicate material (e.g., BK-7) into the desired shape, or by injection molding a suitable polymer or sol-gel. The coating can be formed from any of a variety of suitable materials, such as hafnium dioxide (HfO2), magnesium fluoride (MgF2), and / or tantalum pentoxide (Ta2O5).

[0071] Figure 2AAnother waveguide combiner 320 according to an embodiment of the present disclosure is schematically shown. Waveguide combiner 320 is similar to waveguide combiner 20 and has wFOV-U and wFOV-D selected for the image wFOV and conjugate wFOV, respectively. However, waveguide combiner 320 includes a waveguide 330 having a facet 342 tilted at an angle β that is greater than the angle of tilt of the facet 42 in waveguide combiner 20. Furthermore, unlike waveguide combiner 20, waveguide combiner 320 is configured so that light rays in both wFOV-D and wFOV-U are incident on the same side of facet 242, that is, the side facing TIR surface 32.

[0072] To provide the same side incidence presented to the waveguide combiner 320, calculations similar to those performed from the waveguide combiner 20 result in the following constraints on the waveguide combiner 320. For all γ,

[0073] 14)

[0074] 15)

[0075] 16)(30°+α + / 3)<β<(45°+α - / 2) or (30°+Φ / 6)<β<(45°-Φ / 4);

[0076] The angular upper and lower ranges of the waveguide combiner 32 become,

[0077] 17) as well as

[0078] 18)

[0079] where φ u and φ d are the incident angles of light waves in wFOV-U and wFOV-D, respectively.

[0080] As a numerical example of the waveguide 330, for a wavelength n of about 550 nm, g Equal to approximately 1.5, absolute value |α + | and |α -| is equal to approximately 13°, and Φ′ has a diagonal extent of approximately 30° and an aspect ratio of 16:9, β may be equal to approximately 35°. The upper range of incidence angles selected for the image wFOV, i.e., the reflectivity angular range, advantageously extends from approximately 26° to approximately 44°, and is optionally characterized by an average reflectivity between approximately 9% and 11%, and optionally equal to or greater than 10%. The lower range of transmittance angular range selected for the conjugate wFOV, i.e., the transmittance angular range, advantageously extends from approximately 66° to approximately 84°, and is characterized by an average reflectivity of less than or equal to approximately 5%, and optionally equal to or less than 2%. The see-through range advantageously extends from approximately 15° to approximately 55°, and is characterized by a transmittance equal to or greater than approximately 85%.

[0081] Figure 2B A graph 350 is shown of the reflectivity of a facet 242 that can optionally be manufactured in a manner similar to the manner in which facet 42 is manufactured to substantially conform to the numerical specifications discussed above. The graph includes a reflectivity curve 312 that gives the reflectivity of the facet 242 in the waveguide 330 as a function of the angle of incidence of light on the facet. The reflectivity expressed as a percentage is shown along the ordinate of the graph 351, and the angle of incidence of the light on the facet 242 is shown along the abscissa. The upper range of angles of incidence selected as the image wFOV and the reflectivity angular range is schematically represented by the shaded area 351. The lower range of angles of incidence selected as the transmittance angular range and the conjugate wFOV is schematically represented by the shaded area 352. In accordance with an embodiment of the present disclosure, the dashed cap function 353 indicates the reflectivity of the facet for natural light 74 ( Figure 1A )'s "perspective" angle range.

[0082] Figure 3A Another waveguide combiner 420 according to an embodiment of the present disclosure is schematically shown. The waveguide combiner 420 is similar to Figure 2A Waveguide combiner 320 is shown, but includes a waveguide 430 having facets 442 tilted at a tilt angle β that is greater than the tilt angle of facets 342 in combiner waveguide 330. However, waveguide combiner 420 is configured like waveguide combiner 320 so that light rays in both wFOV-D and wFOV-U are incident on the same side of facets 342 in waveguide combiner 420 (the side facing facet surface 32), and unlike in waveguide combiner 320, wFOV-D is the image wFOV and wFOV-U is the conjugate wFOV.

[0083] For the waveguide combiner 420,

[0084] 19)γ ± =180°-2β-α ± , or γ = 180° - 2β - α, and note that for combiner 420, γ- >γ + , in order to provide a construction of the waveguide combiner 420 where wFOV-D rather than wFOV-U is the image wFOV, the following constraints are satisfied:

[0085] 20)

[0086] 21)β>45°-α - / 2, and

[0087] twenty two)

[0088] 23)β<90°-(α + +θ c ) / 2

[0089] Combining Expressions 21 and 23 gives the following expression for the constraint on β,

[0090] 24) 45°-α - / 2<β<90°-(α+ + θ c ) / 2

[0091] The angular upper range (i.e., transmittance range) and angular lower range (i.e., reflectivity range) of the waveguide combiner 420 can be written as,

[0092] 25) as well as

[0093] 26)

[0094] Figure 3B A graph 450 is provided showing the angular position and range of an upper range (transmittance range) 451 , a lower range (reflectivity range) 452 , and a see-through range 453 for facets 442 in a waveguide 430 .

[0095] As a numerical example of the waveguide 430, it is assumed that for a wavelength n of 550 nm g Equal to approximately 1.51, absolute value |α + | and |α -| is equal to about 13°, and Φ′ has a diagonal length of about 30° and an aspect ratio of 16:9, β may be equal to 63.5°. The upper range of incident angles, i.e., the transmittance angle range, advantageously extends from about 2° to about 20° and has a relatively low average reflectivity that is advantageously less than about 5% and optionally less than or equal to about 2.0%. The lower range selected for the reflective angle range and image FOV advantageously extends from about 55° to about 75° and has a relatively high average reflectivity between about 9% and about 11%, and optionally greater than or equal to 10%. The see-through range advantageously extends from about 40° to about 80° and is characterized by a transmittance equal to or greater than about 85%.

[0096] Figure 3B A graph 450 is shown of the reflectivity of a facet 342 that can optionally be manufactured in a manner similar to the manner in which facet 42 is manufactured to substantially conform to the numerical specifications discussed above. The graph includes a reflectivity curve 412 that gives the reflectivity of the facet 342 in the waveguide 430 as a function of the angle of incidence of light on the facet. The reflectivity expressed as a percentage is shown along the ordinate of the graph 351, and the angle of incidence of light on the facet 342 is shown along the abscissa. The upper range of angles of incidence that is selected as the conjugate wFOV and transmittance angular range is schematically represented by the shaded area 451. The lower range of angles of incidence that is selected as the reflectivity angular range and image wFOV is schematically represented by the shaded area 452. In accordance with an embodiment of the present disclosure, the dashed cap function 453 indicates the reflectivity of the facet for natural light 74 ( Figure 1A )'s perspective angle range.

[0097] More generally, suppose v u denoted in the wFOV-U contained in the waveguide 30, 330 or 430 of the waveguide combiner 20, 320 or 420 - but not necessarily in the wFOV-U for Figure 1B 、 2B Or the normalized vector in the propagation direction of the upward ray in plane AA shown in the waveguide combiner in 3B. Then, the incident angle φ of the upward ray on the small facet of the waveguide relative to the normal of the small facet is u It can be given by the following expression,

[0098] 27)φ u =cos -1 (v u ·n f ),

[0099] where n f is a vector normal to the facet. Similarly, if v drepresents the propagation direction of the downward ray contained in wFOV-D but not necessarily in plane AA, then the incident angle φ of the ray on the small facet of the waveguide d can be written as:

[0100] 28)φ d =cos -1 (v d ·n f )=cos -1 ((v u -2v u ·n w )·n f ),

[0101] where n W is the normal vector to the TIR surface of the waveguide.

[0102] The constraints on the waveguide combiner according to embodiments of the present disclosure discussed above with reference to plane AA can be summarized as v u and / or v d For example, for the waveguide combiner 420, equations 24) and 25) can be rewritten as,

[0103] 29) and 30)

[0104] Note that in the above discussion, it has been assumed that each facet in the combiner waveguide according to embodiments is designed to have a reflectivity and transmittance angular range for each of R light, G light, and B light. However, the practice of embodiments of the present disclosure is not limited to facets having angular ranges for each of R light, G light, and B light. Facets according to embodiments can be designed for colors other than R, G, and B, and can be configured for more or less than three colors. For example, each facet can be designed for only one or only two of R, G, or B.

[0105] It is also noted that the spacing between the facets may advantageously differ from Figure 1B 、 Figure 2A or Figure 3A The spacing between facets is referred to as the facet pitch "P" and can be defined by the expression P = ηLcosβ, where L is the length of the facet between the TIR surfaces and η is a coefficient, typically less than one. Figure 1B and Figure 2A In , η is substantially equal to 1 and the pitch P is shown to be substantially equal to P = Lcosβ. Figure 3A, η is substantially equal to 0.7 and P = 0.7Lcosβ. A smaller pitch P may advantageously provide spatial integrity to the virtual image provided by the waveguide combiner according to embodiments.

[0106] According to an embodiment of the present disclosure, the waveguide combiner discussed above by way of example expands the input aperture 35 in one direction along the y-axis (e.g., as Figure 1A According to an embodiment of the present disclosure, the input aperture can be expanded in the x-direction by replacing the waveguide combiner. Figure 1A The input coupler 50 in the waveguide combiner shown in FIG. 1 is used to provide a waveguide combiner that expands the input aperture in two directions (eg, the x-direction and the y-direction).

[0107] Figure 4 A waveguide combiner 500 is schematically shown that expands an input aperture 535 in two (optionally, orthogonal) directions to provide an expanded outcoupling region 536 through which the waveguide combiner guides light into an EMB 560 in accordance with an embodiment of the present disclosure.

[0108] According to an embodiment of the present disclosure, the waveguide combiner 500 optionally includes a prismatic input coupler 550, a first waveguide 530, and a second waveguide 630. The input coupler 550 receives light from a virtual image generated by the laser display engine 570 through an input aperture 535 and inputs the light into the waveguide 530. The waveguide 530 includes a first TIR facet surface 531 and a second TIR facet surface 532, respectively, which are arbitrarily parallel to the xy plane of the coordinate system 100, as well as a top surface 532 and a bottom surface 534. According to an embodiment of the present disclosure, the waveguide has an output coupler 540 including a plurality of parallel facets 542. Optionally, these facets are perpendicular to the facet surfaces 531 and 532 and rotated about the z-axis by a tilt angle β*. Optionally, these facets are evenly spaced. Light rays of light received from the input coupler 550 are repeatedly totally reflected between the TIR-face surface 531 and the TIR-face surface 532 and reflected back and forth therebetween until they reach and are incident on the facets 542 of the output coupler 540. The facets 542 are distributed over relatively extended distances along the x-axis direction and cause the light rays to reflect out of the waveguide 530 in a direction generally along the negative y-axis and into the waveguide 630 through an extended output aperture 545 that extends the input aperture 535 in the x-direction. The waveguide 630 can be any waveguide configured to receive light from an image generated by a display engine via an input aperture such as the input aperture 535 and project the received light out of the waveguide via an output coupling region that extends substantially in a single direction such as the output coupling region 545.

[0109] As an example, assume that waveguide 630 is similar to waveguide 30, including facet 42 and TIR face surfaces 31 and 32 that are parallel to the xy plane and optionally continuous with face surfaces 531 and 532, respectively. Waveguide 630 expands the image in 545 of waveguide 530 in the negative y-direction and reflects the light it receives from waveguide 530 into EMB 560 through outcoupling region 536 that extends in both the x-direction and the y-direction. Note that although waveguide 630 is assumed to be similar to Figure 1A , but waveguide 630 may be similar to various waveguides, such as waveguide 330 ( FIG. 1 ) including facets and constructed according to embodiments of the present disclosure. Figure 2A ) or waveguide 430( Figure 3A ) in any waveguide.

[0110] Equations 25) and 26) can be linked to relate the desired constraints on the output field of view provided by the waveguide combiner 500 to the EMB 560. The upward and downward directed rays propagating in the waveguide 530 relative to the facet surfaces 531 and 532 are represented by the vector v u (530) and v d (530) indicates that then

[0111] 31)v d (630)=(v u (630)-(2v u (630)·n W )n W ,

[0112] where n W is the normal to the facet surfaces 531, 532, 31, and 32 in the waveguide combiner 500, and the upward and downward directed light rays are arbitrarily considered to travel in the negative z-direction and the positive z-direction, respectively. One of the upward directed light ray group and the downward directed light ray group propagating in the waveguide 530 is reflected by the facet 542 into the waveguide 630. As an example, assume that v u The light (530) is reflected into the waveguide 630. Then, since the reflection of the facet 542 does not change the propagation component of the light in the z direction, the v after reflection by the facet 542 is u (530) The light enters the waveguide 630 as an upwardly directed light relative to the face surface 31 and the face surface 32. The upwardly directed light after entering the waveguide 630 is directed by v u (630). Then, as a result of being reflected into waveguide 630 by facet 542 in waveguide 530, upon entering waveguide 630, ray v u (630) has the direction given by

[0113] 32)v u (630) = v u (530)-2(v u (530)·n f (542)n f .

[0114] After being reflected by the face surface 32, the upwardly directed v u (630) “becomes” a downward-directed ray v d (630), among which

[0115] 33)v d (630) = v u (630)-2(v u (630)·n W )n W .

[0116] The upwardly directed light and the downwardly directed light in the waveguide 630 are respectively contained in Figure 1A 、 Figure 2A and Figure 3A Schematically shown are an upward-directed field of view wFOV-U and a downward-directed field of view wFOV-D. And according to an embodiment, light rays in one of wFOV-U and wFOV-D in waveguide 630 are selected for reflection by facet 42 through outcoupling region 536 in output field of view O-FOV into EMB 560. The desired constraints on the light rays in O-FOV can be back-propagated to harmonize the tilt angles β and β* that characterize the facets 42 and 542 in waveguides 30 and 530.

[0117] The present invention also discloses the following configuration:

[0118] 1. A waveguide combiner comprising:

[0119] The first waveguide includes a waveguide having a normal "n W "a first parallel total internal reflection surface and a second parallel total internal reflection surface;

[0120] an input aperture through which light enters the first waveguide;

[0121] an output coupling structure associated with an output coupling region, the output coupling structure expanding the input aperture in at least one direction and through which light entering the first waveguide exits the first waveguide; and

[0122] An output coupler comprising a plurality of parallel facets embedded in the first waveguide and having a plurality of parallel facets disposed between n and n. WThe normal to the facet "n f ”, the facet reflects the light propagating along the first waveguide and incident on the facet through the output coupling region, and the facet has:

[0123] a facet wavelength band for each of at least one lasing band of light provided by the laser, the facet wavelength band including wavelengths of light in the lasing band and in a range of wavelengths over which the lasing band is expected to vary;

[0124] a reflectivity angular range exhibiting a first reflectivity for light propagating in the first waveguide with a wavelength in the facet wavelength band and incident on the facet within a first range of incidence angles;

[0125] a transmittance angular range exhibiting a second reflectivity less than the first reflectivity for light having a wavelength in the facet wavelength band propagating in the first waveguide and incident on the facet within a second range of incidence angles; and

[0126] A perspective angle transmittance range has a high transmittance for natural light incident on the facet within a third incident angle range.

[0127] 2. The waveguide combiner of configuration 1 , wherein an average reflectivity for incident angles within the reflectivity angular range and wavelengths in the facet wavelength band is between about 9% and about 11%.

[0128] 3. The waveguide combiner of configuration 2, wherein a variation in reflectivity of the facet for incident angles within the reflectivity angular range and wavelengths in the facet wavelength band is less than about 2.5% of the average reflectivity.

[0129] 4. The waveguide combiner of any one of configurations 1 to 3, wherein the angular width of the reflectivity angular range is greater than or equal to about 15° or about 20°.

[0130] 5. The waveguide combiner of configurations 1 to 4, wherein a lower limit of the reflectivity angle range is about 2°, about 25°, or about 50°.

[0131] 6. A waveguide combiner according to any one of configurations 1 to 5, wherein the average reflectivity for incident angles within the transmittance angular range and wavelengths in the facet wavelength band is between about 0.5% and about 5%.

[0132] 7. The waveguide combiner of any one of configurations 1 to 6, wherein an angular width of the transmittance angular range is greater than or equal to approximately 15° or approximately 30°.

[0133] 8. The waveguide combiner of any one of the preceding configurations, wherein a lower limit of the transmittance angular range is about 2°, about 50°, or about 60°.

[0134] 9. A waveguide combiner according to any of the preceding configurations, wherein, for each facet wavelength band, a variation in reflectivity for wavelengths in the band relative to an average reflectivity in the wavelength band is less than an upper limit such that a gamut chromaticity difference radius "ΔCG" in the CIE 1931xy chromaticity space is less than or equal to approximately 0.02.

[0135] 10. The waveguide combiner of configuration 9, wherein if an average reflectivity of wavelengths in the facet wavelength band is represented by R and a maximum difference between the reflectivity of wavelengths in the facet wavelength band and R is represented by ΔR, |ΔR| / R is less than or equal to approximately 3%.

[0136] 11. The waveguide combiner of any preceding configuration, wherein the at least one lasing band comprises at least one or any combination of more than one of red, green, and / or blue lasing bands.

[0137] 12. The waveguide combiner of any of the preceding configurations, wherein a bandwidth of the facet wavelength band for a lasing band in the at least one lasing band is greater than or equal to three times the bandwidth of the lasing band or greater than or equal to four times the bandwidth of the lasing band.

[0138] 13. The waveguide combiner of any one of the preceding configurations, wherein the transmittance of the perspective angle range is greater than or approximately equal to 85%.

[0139] 14. The waveguide combiner according to any one of the preceding configurations, wherein an angular width of the perspective angle range is greater than or equal to 30° or 40°.

[0140] 15. The waveguide combiner of any of the preceding configurations, wherein a lower limit of the perspective range is approximately 5°, 15°, or 40°.

[0141] 16. A waveguide combiner according to any one of configurations 1 to 15, wherein (90°-γ)>β, γ>θ c , where γ represents n W and the angle on the facet surface between the incident direction of a ray propagating in the first waveguide and from which the output coupler reflects the light out of the first waveguide through the output coupling region, and θ c represents the critical angle of the first waveguide for light having a wavelength in the facet wavelength band.

[0142] 17. The waveguide combiner of configuration 16, wherein the tilt angle β satisfies the constraint (θ c +α + ) / 2<β<(30°+α _ / 3), where α + and α - is the angle between the normal to the facet surface and the direction in which the facet reflects incident light out of the first waveguide, in a plane perpendicular to the facet surface and the facet, and wherein α + Greater than α - , and is positive if the rotation is clockwise relative to the normal and negative if the rotation is counterclockwise relative to the normal, and where α + and α - A minimum value and a maximum value of γ are respectively determined that define the field of view wFOV of the light propagating in the first waveguide.

[0143] 18. The waveguide combiner of configuration 17, wherein the reflectivity angular range spans the full range of incident angles φ, wherein (β-α + )≤φ≤(β-α - ).

[0144] 19. The waveguide combiner of configuration 17 or configuration 18, wherein the transmittance angular range spans the full range of incident angles φ, wherein (3β-α + )≤φ≤(3β-α - ).

[0145] 20. The waveguide combiner of any one of configurations 1 to 15, wherein β>(90°-γ).

[0146] 21. The waveguide combiner of configuration 20, wherein the tilt angle β satisfies the constraint (30° + α + / 3)<β<(45°+α _ / 2).

[0147] 22. The waveguide combiner of configuration 21, wherein the reflectivity angular range spans the full range of incident angles φ, wherein (β-α + )≤φ≤(β-α - ).

[0148] 23. The waveguide combiner of configuration 21 or configuration 22, wherein the transmittance angular range spans the full range of incident angles φ, where (180°-3β+α - )≤φ≤(180°-3β+α + ).

[0149] 24. The waveguide combiner of configuration 20, wherein the tilt angle β satisfies the constraint 45°-α - / 2<β<90°-(α + +θ c ) / 2.

[0150] 25. The waveguide of configuration 24, wherein the reflectivity angular range spans the full range of incident angles φ, wherein (β+α - )≤φ≤(β+α + ).

[0151] 26. The waveguide combiner of configuration 24 or configuration 25, wherein the transmittance angular range spans the full range of incident angles φ, wherein (180°-3β-α + )≤φ u ≤(180°-3β-α - ).

[0152] 27. A waveguide combiner according to any of the preceding configurations, comprising a second waveguide having a second input aperture and a second output coupling region, light received through the second input aperture exiting the second waveguide through the second output coupling region and entering the first waveguide, and wherein the second output coupling region is expanded relative to the second input aperture in a direction different from the at least one direction in which the output aperture of the first waveguide is expanded.

[0153] In the specification and claims of this application, the verbs "comprise," "include," and "have," and their conjugations, are each used to indicate that the object or objects of the verb are not necessarily a complete list of parts, elements, or portions of the subject or subjects of the verb.

[0154] The description of the embodiments of the present disclosure in this application is provided by way of example and is not intended to limit the scope of the present disclosure. The described embodiments include different features, not all of which are required in all embodiments. Some embodiments utilize only some features or possible combinations of features. Those skilled in the art will recognize variations of the described embodiments of the present disclosure and embodiments including different combinations of the features mentioned in the described embodiments. The scope of the present invention is limited only by the claims.

Claims

1. A waveguide combiner comprising: The first waveguide comprises a waveguide having a normal n w a first parallel total internal reflection surface and a second parallel total internal reflection surface; an input aperture through which light enters the first waveguide; an output coupling structure associated with an output coupling region, the output coupling structure expanding the input aperture in at least one direction and through which light entering the first waveguide exits the first waveguide; as well as An output coupler configured for use with at least one laser and comprising a plurality of parallel facets embedded in the first waveguide and having a plurality of parallel facets disposed between n and n. w Normal n to the facet f The facets have a facet inclination angle β between them, the facets reflecting light propagating along the first waveguide and incident on the facets out through the outcoupling region, each of the facets having a coating that provides: a facet wavelength band for a lasing band of light provided by the at least one laser, the facet wavelength band including wavelengths of light in the lasing band and in a range of wavelengths within which the lasing band is expected to vary; a reflectivity angular range exhibiting a first reflectivity for light propagating in the first waveguide with a wavelength in the facet wavelength band and incident on the facet within a first range of incidence angles; a transmittance angular range exhibiting a second reflectivity less than the first reflectivity for light having a wavelength in the facet wavelength band propagating in the first waveguide and incident on the facet within a second range of incidence angles; and A perspective angle transmittance range has a high transmittance for natural light incident on the facet within a third incident angle range.

2. The waveguide combiner according to claim 1, wherein For each facet wavelength band, the reflectivity of the wavelengths in the band varies less than an upper limit relative to the average reflectivity in the wavelength band, so that the gamut chromaticity difference radius ΔCG in the CIE 1931xy color space is less than or equal to about 0.

02.

3. The waveguide combiner according to claim 2, wherein: If an average reflectivity of wavelengths in the facet wavelength band is represented by R and a maximum difference between the reflectivity of wavelengths in the facet wavelength band and R is represented by ΔR, |ΔR| / R is less than or equal to about 3%.

4. The waveguide combiner according to claim 1, wherein The laser emission band includes one of a red, green and / or blue laser emission band.

5. The waveguide combiner according to claim 1, wherein The bandwidth of the facet wavelength band for the lasing band is greater than or equal to three times the bandwidth of the lasing band or greater than or equal to four times the bandwidth of the lasing band.

6. The waveguide combiner according to claim 1, in, (90°-γ)>β,γ>θ c , Where γ represents n w and the angle between the incident direction on the facet surface of a ray propagating in the first waveguide and from which the output coupler reflects light out of the first waveguide through the output coupling region, and Among them, θ c represents the critical angle of the first waveguide for light having a wavelength in the facet wavelength band.

7. The waveguide combiner according to claim 6, in, The inclination angle β satisfies the constraint (θ c +α+) / 2<β<(30°+α - / 3), Among them, α + and α - is the angle between the normal to the facet surface and the direction in which the facet reflects incident light out of the first waveguide, in a plane perpendicular to the facet surface and the facet, Among them, α + Greater than α - , and is positive if the rotation is clockwise relative to the normal, and negative if the rotation is counterclockwise relative to the normal, and Among them, α + and α - A minimum value and a maximum value of γ are respectively determined that define the field of view wFOV of the light propagating in the first waveguide.

8. The waveguide combiner according to claim 7, wherein: The reflectivity angle range spans the full range of incident angles φ, where (β-α + )≤φ≤(β-α - ).

9. The waveguide combiner according to claim 7, wherein: The transmittance angular range spans the full range of incident angles φ, where (3β-α + )≤φ≤(3β-α - ).

10. The waveguide combiner according to claim 1, wherein β>(90°-γ).

11. The waveguide combiner according to claim 10, wherein: The inclination angle β satisfies the constraint (30°+α + / 3)<β<(45°+α - / 2).

12. The waveguide combiner according to claim 11, wherein The reflectivity angle range spans the full range of incident angles φ, where (β-α + )≤φ≤(β-α - ).

13. The waveguide combiner according to claim 11, wherein The transmittance angle range spans the full range of incident angles φ, where (180°-3β+α - )≤φ≤(180°-3β+α + ).

14. The waveguide combiner according to claim 10, wherein: The inclination angle β satisfies the constraint 45°-α - / 2<β<90 ° -(α + +θ c ) / 2.

15. The waveguide according to claim 14, wherein The reflectivity angle range spans the full range of incident angles φ, where (β+α - )≤φ≤(β+α + ).

16. The waveguide combiner of claim 14, wherein: The transmittance angle range spans the full range of incident angles φ, where (180°-3β-α + )≤φ u ≤(180°-3β-α - ).

17. The waveguide combiner of claim 1 , comprising a second waveguide having a second input aperture and a second outcoupling region, light received through the second input aperture exiting the second waveguide through the second outcoupling region and entering the first waveguide, and wherein The second outcoupling region is expanded relative to the second input aperture in a direction different from the at least one direction in which the output aperture of the first waveguide is expanded.

18. A waveguide combiner comprising: The first waveguide comprises a waveguide having a normal n w a first parallel total internal reflection surface and a second parallel total internal reflection surface; an input aperture through which light enters the first waveguide; an output coupling structure associated with an output coupling region, the output coupling structure expanding the input aperture in at least one direction and through which light entering the first waveguide exits the first waveguide; as well as An output coupler configured for use with at least one laser and comprising a plurality of parallel facets embedded in the first waveguide and having a plurality of parallel facets disposed between n and n. w Normal n to the facet f The facets have a facet inclination angle β between them, wherein the facets reflect the light propagating along the first waveguide and incident on the facets out through the output coupling region, and the facets have: a facet wavelength band for a lasing band of light provided by the at least one laser, the facet wavelength band including wavelengths of light in the lasing band and in a range of wavelengths within which the lasing band is expected to vary; a reflectivity angular range exhibiting a first reflectivity for light propagating in the first waveguide with a wavelength in the facet wavelength band and incident on the facet within a first range of incidence angles; a transmittance angular range exhibiting a second reflectivity less than the first reflectivity for light having a wavelength in the facet wavelength band propagating in the first waveguide and incident on the facet within a second range of incidence angles; and a perspective angle transmittance range having high transmittance for natural light incident on the facet within a third incident angle range, Wherein, (90°-γ)>β,γ>θ c , Where γ represents n w an angle between a direction of incidence on the facet surface of a ray propagating in the first waveguide and from which the output coupler reflects light out of the first waveguide through the output coupling region; and Among them, θ c represents the critical angle of the first waveguide for light with a wavelength in the facet wavelength band, Among them, the inclination angle β satisfies the constraint (θ c +α + ) / 2<β<(30°+α - / 3), Among them, α + and α - is the angle between the normal to the facet surface and the direction in which the facet reflects incident light out of the first waveguide, in a plane perpendicular to the facet surface and the facet, Among them, α + Greater than α - , and is positive if the rotation is clockwise relative to the normal, and negative if the rotation is counterclockwise relative to the normal, and Among them, α + and α - determining the minimum and maximum values ​​of γ respectively defining the field of view wFOV of the light propagating in said first waveguide, The reflectivity angle range spans the full range of incident angles φ, where (β-α + )≤φ≤(β-α - ),and The transmittance angle range spans the full range of incident angles φ, where (3β-α + )≤φ≤(3β-α - ).

Images