Patent Description:
Wearable heads-up displays use optical combiners to combine real world and virtual images. There are two main classes of optical combiners used in wearable heads-up displays: free-space combiners and substrate-guided combiners. Holographic combiners are examples of free-space combiners, and lightguide (or waveguide) combiners are examples of substrate-guided combiners. Holographic combiners use one or more holograms to redirect light from a light source to a target. In lightguide combiners, light enters the lightguide, typically through an in-coupling element, propagates along the length of the lightguide by total internal reflection (TIR), and exits the lightguide, typically through an out-coupling element. In wearable heads-up displays having the form of eyeglasses, the optical combiners are integrated into at least one lens that is fitted in a support frame, where the at least one lens may or may not be a prescription lens. For a wearable heads-up display that is intended to be worn on the head for prolonged periods, it is desirable that the combiner-lens integration is lightweight while providing any desired prescription. Document <CIT> discloses an optical combiner lens comprising a lightguide in stack with a first lens and a second lens.

In one aspect, an optical combiner lens includes a first lens, a second lens, a lightguide in stack with the first lens and the second lens, an in-coupler physically coupled to the lightguide and positioned to receive light into the lightguide, an out-coupler physically coupled to the lightguide and positioned to output light from the lightguide, a first medium gap defined within the stack and between the first lens and the lightguide, and a second medium gap defined within the stack and between the lightguide and the second lens.

The first lens may be a meniscus lens. The first lens may have an optical power of zero. The first lens and the out-coupler may have a combined optical power that is positive or negative.

The first lens may have an optical power that is zero, positive, or negative.

The second lens may have an optical power that is zero, positive, or negative.

The first lens may be a planoconvex lens.

The second lens may be a biconcave lens, a planoconcave lens, or a meniscus lens.

Each of the first medium gap and the second medium gap may contain a respective medium having a refractive index that is lower than a refractive index of the lightguide.

The lightguide is physically coupled to the first lens and the second lens.

The first medium gap may be defined between an inner surface of the first lens and the lightguide.

The second medium gap may be defined between an inner surface of the second lens and the lightguide.

The lightguide is physically coupled to the first lens and the second lens by an edge support structure that holds the first lens, the lightguide, and the second lens in a spaced apart relation in the stack. The edge support structure may circumscribe a periphery of the stack and seal the first and second medium gaps proximate the periphery of the stack. The edge support structure may be integrally formed with an edge of the first lens.

The in-coupler is physically coupled to an input area of lightguide that is not in registration with the first lens and the second lens. The edge support structure is made of a transparent material, or includes an aperture or transparent section to allow light to travel to the in-coupler in the input area of the lightguide within the edge support structure.

Each of the in-coupler and out-coupler may include at least one of a hologram, a volume diffracting grating, a surface relief grating. Each of the in-coupler and out-coupler may be a transmission coupler or a reflection coupler.

The lightguide may be a planar lightguide.

The optical combiner lens may have a shape of an eyeglass.

In a second aspect, a wearable heads-up display includes a support structure that in use is worn on a head of a subject, a display light source coupled to the support structure, and an optical combiner lens as summarized above. Optical powers of the first lens and out-coupler of the optical combiner may be selected to position a display from the display light source at a select focal distance, and an optical power of the second lens may be optionally selected based on an eyeglasses prescription. The display light source may be a projector, a scanning laser projector, or a microdisplay.

The foregoing general description and the following detailed description are exemplary of the invention and are intended to provide an overview or framework for understanding the nature of the invention as it is claimed. The accompanying drawings are included to provide further understanding of the invention and are incorporated in and constitute part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the particular elements and have been solely selected for ease of recognition in the drawing. A part of the attached figures show examples of an optical combiner lens and a wearable heads-up display which do not comprise the features of the proposed solution as defined in appended claims <NUM> or <NUM> but are helpful for understanding the proposed solution and potential embodiments.

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with portable electronic devices and head-worn devices have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the implementations or embodiments. For the sake of continuity, and in the interest of conciseness, same or similar reference characters may be used for same or similar objects in multiple figures. For the sake of brevity, the term "corresponding to" may be used to describe correspondence between features of different figures. When a feature in a first figure is described as corresponding to a feature in a second figure, the feature in the first figure is deemed to have the characteristics of the feature in the second figure, and vice versa, unless stated otherwise.

In this disclosure, unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to.

In this disclosure, reference to "one implementation" or "an implementation" or to "one embodiment" or "an embodiment" means that a particular feature, structures, or characteristics may be combined in any suitable manner in one or more implementations or one or more embodiments.

In this disclosure, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its broadest sense, that is, as meaning "and/or" unless the content clearly dictates otherwise.

The headings and Abstract of the disclosure are for convenience only and do not interpret the scope or meaning of the embodiments.

<FIG> shows an optical combiner lens <NUM> according to one illustrative implementation. Optical combiner lens <NUM> includes a stack <NUM> composed of a first lens <NUM>, a lightguide <NUM>, and a second lens <NUM>. Lightguide <NUM> is disposed between first lens <NUM> and second lens <NUM>. In the illustrated example, lightguide <NUM> extends across a full width of the first lens <NUM> and second lens <NUM>. In the illustrated example, lightguide <NUM> has an input area 112a that extends past the full width of first lens <NUM> and second lens <NUM> (i.e., input area 112a is not in registration with first lens <NUM> and second lens <NUM>). In the illustrated example, first lens <NUM> is a meniscus lens having an outer convex surface <NUM> and an inner concave surface <NUM>. Surfaces <NUM>, <NUM> of first meniscus lens <NUM> are separated by the respective lens thickness. Lightguide <NUM> has a top lightguide surface <NUM> and a bottom lightguide surface <NUM>. In the illustrated example, second lens <NUM> is a biconcave lens having an inner concave surface <NUM> and an outer concave surface <NUM>. Surfaces <NUM>, <NUM> of second biconcave lens <NUM> are separated by the respective lens thickness.

Outer convex surface <NUM> of first meniscus lens <NUM> may be the world side of optical combiner lens <NUM>, and outer concave surface <NUM> of second biconcave lens <NUM> may be the eye side of optical combiner lens <NUM>. Inner concave surface <NUM> of first meniscus lens <NUM> is in opposing relation to top lightguide surface <NUM>. Inner concave surface <NUM> and top lightguide surface <NUM> define a first medium gap <NUM> within stack <NUM>. The term "medium gap" refers to a gap or cavity or space that may contain a medium, which may be a gaseous material, a liquid material, or a solid material. Inner concave surface <NUM> of second biconcave lens <NUM> is in opposing relation to bottom lightguide surface <NUM>. Inner concave surface <NUM> and bottom lightguide surface <NUM> define a second medium gap <NUM> within stack <NUM>. In one implementation, each of medium gaps <NUM>, <NUM> is hermetically sealed. The seal may be formed at or proximate a periphery of stack <NUM>.

The term "lightguide," as used herein, will be understood to mean a combiner using total internal reflection (TIR) to transfer collimated light. For display applications, the collimated light may be a collimated image, and the lightguide transfers and replicates the collimated image to the eye. The light propagating through lightguide <NUM> may be visible light (e.g., including any combination of red light, green light, and blue light). In some cases, the light propagating through lightguide <NUM> may also include infrared light. In one example, lightguide <NUM> is an optical substrate that transmits light. In one implementation, each of medium gaps <NUM>, <NUM> contains a medium with an index of refraction that is substantially different from that of lightguide <NUM>, allowing light to travel along lightguide <NUM> by TIR. In one example, the medium in each of medium gaps <NUM>, <NUM> is air. In other examples, the medium in each of medium gaps <NUM>, <NUM> may be other gaseous material besides air, such as nitrogen. In yet other examples, the medium in each of medium gaps <NUM>, <NUM> may be a liquid material, an oil, an adhesive material, or an optical material. The media in medium gaps <NUM>, <NUM> may be the same or may be different. In other examples, lightguide <NUM> may be a dielectric waveguide including a core between two claddings, where the core has a higher refractive index compared to the claddings and light propagates within the core. In the illustrated example, lightguide <NUM> is a planar lightguide (i.e., has a planar or rectilinear geometry). Alternatively, lightguide <NUM> may be a curved lightguide, where at least one of the lightguide surfaces <NUM>, <NUM> is a curved surface (i.e., not lying flat or not in a plane).

An in-coupler <NUM> is provided in input area 112a of lightguide <NUM> to couple light into lightguide <NUM>. In general, the term "coupler" will be understood to refer to any type of optical grating structure, including, but not limited to, diffraction gratings, holograms, holographic optical elements (e.g., optical elements using one or more holograms), volume diffraction gratings, volume holograms, surface relief diffraction gratings, and/or surface relief holograms. A coupler may be of the transmission type, meaning the coupler transmits light and applies designed optical function(s) to the light during the transmission, or of the reflection type, meaning the coupler reflects light and applies designed optical function(s) to the light during the reflection.

<FIG> shows light traveling along lightguide <NUM> by TIR (<FIG> has been slightly simplified relative to <FIG>, e.g., cross-sectional hatches have been omitted, to avoid cluttering the drawing). In the example shown in <FIG>, in-coupler <NUM> is illustrated as a transmission coupler. If in-coupler <NUM> is a reflection coupler, in-coupler <NUM> would be positioned nearer the top of lightguide <NUM>, where the coupler will be able to receive incoming light and reflect the light into the lightguide, as illustrated in <FIG>. An out-coupler <NUM> is provided in an output area 112b of lightguide <NUM>. Output area 112b is in a portion of lightguide <NUM> that is in registration with second lens <NUM>. Out-coupler <NUM> may be of the transmission type or the reflection type. In <FIG> and <FIG>, out-coupler <NUM> is illustrated as a transmission coupler. However, out-coupler <NUM> could alternatively be a reflection coupler. <FIG> also shows that in-coupler <NUM> does not have to be the same type of coupler as out-coupler <NUM>.

Returning to <FIG>, in one example, an adhesive layer <NUM> is disposed between first meniscus lens <NUM> and lightguide <NUM> to attach first meniscus lens <NUM> to lightguide <NUM>. In one example, adhesive layer <NUM> is in the form of a loop running along a periphery of inner concave surface <NUM> of first meniscus lens <NUM>, as shown in <FIG>. It should be understood that the lens shape shown in <FIG> is for illustrative purposes and is not intended to be limiting. Returning to <FIG>, in the example where adhesive layer <NUM> is a loop, adhesive layer <NUM> circumscribes a periphery of first medium gap <NUM>, or closes first medium gap <NUM> at a periphery of stack <NUM>. In one example, adhesive layer <NUM> has sealing properties and may prevent moisture and dust from entering first medium gap <NUM>, thereby providing first medium gap <NUM> with a hermetic seal. In one example, a flat (or planar) peripheral surface <NUM> extends radially from a periphery of inner concave surface <NUM>, and the adhesive layer <NUM> is formed between the flat peripheral surface <NUM> and the lightguide <NUM>. As an example, one process for forming the flat peripheral surface <NUM> is to first form the meniscus lens <NUM>, as shown in <FIG>, and then flat grind the concave side of meniscus lens <NUM> by some amount d1. <FIG> shows meniscus lens <NUM> after such grinding to include flat peripheral surface <NUM>. In an alternative implementation, a flat peripheral surface may not extend radially from a periphery of inner concave surface <NUM>, and adhesive layer <NUM> may be formed between a curved peripheral portion of inner concave surface <NUM> and the top lightguide surface <NUM>, as illustrated in <FIG>. In this case, adhesive layer <NUM> will have a varying layer thickness, as shown in <FIG>.

In another example, as shown in <FIG>, a flange <NUM> may be formed around the periphery of first meniscus lens <NUM>. In this case, adhesive layer <NUM> may be formed between a flat (or planar) surface 166a of the flange <NUM> and top lightguide surface <NUM>. In <FIG>, the flat surface 166a of flange <NUM> is level with the periphery of inner concave surface <NUM>. <FIG> shows an example where a flange <NUM> formed around the periphery of first meniscus lens <NUM> has a flat surface 167a that is axially offset by a distance d3 relative to a periphery of inner concave surface <NUM>. The example meniscus lenses with flanges shown in <FIG> and <FIG> may be formed using special molds.

Returning to <FIG>, in one example, an adhesive layer <NUM> is disposed between second biconcave lens <NUM> and lightguide <NUM> to attach second biconcave lens <NUM> to lightguide <NUM>. In one example, adhesive layer <NUM> is in the form of a loop running along a periphery of inner concave surface <NUM> of second biconcave lens <NUM>, as shown in <FIG>. It should be understood that the lens shape shown in <FIG> is for illustrative purposes and is not intended to be limiting. Returning to <FIG>, in the example where adhesive layer <NUM> is a loop, adhesive layer <NUM> circumscribes a periphery of second medium gap <NUM>, or closes second medium gap <NUM> at a periphery of stack <NUM>. In one example, adhesive layer <NUM> has sealing properties and may prevent moisture and dust from entering second medium gap <NUM>, thereby hermetically sealing medium gap <NUM>. In one example, a flat (or planar) peripheral surface <NUM> extends radially from a periphery of inner concave surface <NUM>, and the adhesive layer <NUM> is formed between the flat peripheral surface <NUM> and the lightguide <NUM>. As an example, one process for forming the flat peripheral surface <NUM> is to first form the biconcave lens <NUM>, as shown in <FIG>, and then flat grind a concave side of biconcave lens <NUM> by some amount d2. <FIG> shows the biconcave lens after such grinding to include flat peripheral surface <NUM>. In an alternative implementation, a flat peripheral surface may not extend radially from a periphery of inner concave surface <NUM>, and adhesive layer <NUM> may be formed between a curved peripheral portion of inner concave surface <NUM> and the bottom lightguide surface <NUM>, as illustrated in <FIG>. In this case, the adhesive layer <NUM> will have a varying layer thickness, as shown in <FIG>.

In another example, as shown in <FIG>, a flange <NUM> may be formed around the periphery of second biconcave lens <NUM>. In this case, adhesive layer <NUM> may be formed between a flat (or planar) surface 174a of flange <NUM> and bottom lightguide surface <NUM>. In <FIG>, the flat surface 174a of flange <NUM> is level with the periphery of inner concave surface <NUM>. <FIG> shows an example where a flange <NUM> formed around the periphery of second biconcave lens <NUM> has a flat surface 175a that is axially offset by a distance d4 relative to the periphery of inner concave surface <NUM>. The example biconcave lenses with flanges shown in <FIG> and <FIG> may be formed with special molds.

Returning to <FIG>, in one implementation, first lens <NUM>, second lens <NUM>, and lightguide <NUM> are made of transparent materials, which would allow use of optical combiner lens <NUM> as an eyeglass. First lens <NUM> and second lens <NUM> may be made of any suitable lens material, such as plastic, e.g., polycarbonate, or glass. One or more coatings, such as anti-scratch coating, anti-reflective (AR) coating, and/or IR-blocking coating, may be applied to the outer surface <NUM> of first lens <NUM>. In one example, at least AR coating is applied to the outer and inner surfaces of first lens <NUM> and second lens <NUM>. Lightguide <NUM> may also be made of lens material, or material compatible with lens material, bearing in mind the refractive index requirements for lightguide <NUM> previously described.

In one implementation, at least out-coupler <NUM> is made of transparent material(s). In an alternative implementation, both out-coupler <NUM> and in-coupler <NUM> may be made of transparent material(s). Couplers <NUM>, <NUM> may be physically coupled to lightguide <NUM> by adhering, or otherwise attaching, the couplers to the lightguide or by modifying portions of the lightguide to provide the optical coupling functions.

Coatings may be applied to lightguide <NUM> to enhance functionality of the lightguide. For example, as illustrated in <FIG>, a reflective coating <NUM> may be applied on a surface of lightguide <NUM> opposite in-coupler <NUM> to prevent loss of light through that surface.

Returning to <FIG>, the adhesive material in adhesive layers <NUM>, <NUM> may be any adhesive material that is compatible with lens and lightguide materials. In some cases, the adhesive material may be optically transparent. Preferably, the adhesive material has sealing properties, e.g., nonporous material, so as to keep moisture and dust out of medium gaps <NUM>, <NUM>. In some cases, the adhesive material may be a UV curable resin with properties to adhere to the material of the lenses <NUM>, <NUM> and lightguide <NUM>.

Other methods of securing the components in stack <NUM> besides adhesive layers between first lens <NUM> and lightguide <NUM> and between second lens <NUM> and lightguide <NUM> may be used. In one example according to the proposed solution, as shown in <FIG>, first lens <NUM>, lightguide <NUM>, and second lens <NUM> may be held together by an edge support structure <NUM>. Edges of first lens <NUM>, lightguide <NUM>, and second lens <NUM> may be secured to edge support structure <NUM> by, e.g., an adhesive material. Edge support structure <NUM> may be in a loop form that circumscribes a periphery of stack <NUM> and seals medium gaps <NUM>, <NUM> at the periphery of stack <NUM>. Edge support structure <NUM> may also function as a spacer (or provide spacing) between first lens <NUM> and lightguide <NUM> and between lightguide <NUM> and second lens <NUM>. Edge support structure <NUM> could be made of a transparent material, or may include an aperture (or transparent section), to allow light to travel to in-coupler <NUM> in the input area 112a of lightguide <NUM>. In some cases, edge support structure <NUM> may be integrated as a flange at an edge of first lens <NUM> - first lens <NUM> with such a flange could be formed by molding, for example. Another example is shown in <FIG>, where a sealing tape <NUM> is applied along a periphery of stack <NUM>. Sealing tape <NUM> holds first lens <NUM>, second lens <NUM>, and lightguide <NUM> together while sealing medium gaps <NUM>, <NUM> at the periphery of stack <NUM>. Sealing tape <NUM> may include a hole <NUM> through which the part of lightguide <NUM> including in-coupler <NUM> may protrude. Sealing tape <NUM> may also function as a spacer (or provide spacing) between first lens <NUM> and lightguide <NUM> and between lightguide <NUM> and second lens <NUM>.

Returning to <FIG>, optical combiner lens <NUM> provides four surfaces <NUM>, <NUM>, <NUM>, <NUM> upon which an eyeglasses prescription may be built. Curved inner surfaces <NUM>, <NUM> will affect the size of medium gaps <NUM>, <NUM>, which will have an effect on overall weight and size of optical combiner lens <NUM>. For a given lightguide thickness, the radii of curvature of surfaces <NUM>, <NUM>, <NUM>, <NUM> can be appropriately selected to achieve a desired prescription while also achieving a lens that is relatively thin and lightweight. All the lens surfaces <NUM>, <NUM>, <NUM>, <NUM> shown in <FIG> have curvatures. However, it is possible for some of the surfaces, e.g., inner surfaces <NUM>, <NUM>, to be planar, as will be later described.

In some examples, first meniscus lens <NUM> can be made to have zero optical power. For an ideal meniscus lens with zero thickness, a zero optical power can be achieved by making the radii of curvature of the convex and concave surfaces of the lens equal. However, because first meniscus lens <NUM> does not have zero lens thickness, the radii of curvature of the surfaces <NUM>, <NUM> will need to be slightly unequal to account for the effect of the lens thickness. In the example where first meniscus lens <NUM> has zero optical power, second lens <NUM> (which may be a biconcave lens or other lens type) can have negative or positive optical power, e.g., to provide a prescription function, or zero optical power. In other examples, first meniscus lens <NUM> may have negative or positive optical power, and second lens <NUM> (which may be a biconcave lens or other lens type) may have negative, positive, or zero optical power. Upper and lower bounds for negative and positive optical powers may be governed by the desired prescription to be provided by optical combiner lens <NUM> and/or by display performance when the optical combiner lens <NUM> is used with a display.

One potential advantage of making first meniscus lens <NUM> with zero optical power may be the ability to eliminate compensation for world side optical power from the design of out-coupler <NUM>. This can be understood with reference to <FIG> shows that the world-side light coming out of meniscus lens <NUM> and passing through lightguide <NUM> is focused. At the same time, the lightguide light coming out of out-coupler <NUM> is collimated. A correction may be applied to out-coupler <NUM>, as shown for out-coupler 156a in <FIG>, such that the lightguide light coming out of the out-coupler (156a in <FIG>) is aligned with the world-side light or is also focused. On the other hand, if first meniscus lens <NUM> is made with zero optical power, it will not be necessary for a correction to be applied to the out-coupler to compensate for differences in optical power between the world side light and the lightguide light. A meniscus lens with zero optical power will neither diverge light nor converge light. If first meniscus lens <NUM> has zero optical power, the second lens <NUM> (which may be a biconcave lens or other type of lens) is available to carry the eyeglasses prescription.

In another implementation, differences in optical power between the optical coupler <NUM> and first meniscus lens <NUM> may be useful, i.e., a "correction" may be applied to out-coupler <NUM> to achieve a particular optical power difference between first meniscus lens <NUM> and optical coupler <NUM> (i.e., the combined optical power of the first meniscus lens <NUM> and out-coupler <NUM> is positive or negative). For example, such difference may be exploited to place a display at a desired distance relative to the optical combiner lens or to compensate for distortions in the optical path. In general, the power of a lens to focus at a particular distance is D = <NUM>/F, where D is the optical power in diopters and F is the focal distance in meters. Theoretically, a lens having an optical power of +<NUM> diopters will place a display at approximately <NUM> (F = <NUM>). In this case, outer convex surface <NUM>, inner concave surface <NUM>, and out-coupler <NUM> form surfaces whose optical powers can be selected to achieve +<NUM> diopters (or other desired optical power). As an arbitrary example, outer convex surface <NUM> may have an optical power of +<NUM> diopters, inner concave surface <NUM> may have an optical power of -<NUM> diopters, and optical coupler <NUM> may have an optical power of -<NUM> diopters. If optical coupler <NUM> is a hologram, for example, the hologram can be recorded with the desired optical power. In general, each of outer convex surface <NUM> of meniscus lens <NUM>, inner concave surface <NUM> of first meniscus lens <NUM> and out-coupler <NUM> can be designed with a positive, negative, or zero optical power. If the out-coupler <NUM> is provided with an optical power function, then there will be even more liberty in selecting the optical power of first meniscus lens <NUM> and second lens <NUM> (which may be a biconcave lens or other type of lens).

In an alternative optical combiner lens <NUM>' shown in <FIG>, a planoconcave lens <NUM>' (instead of a biconcave lens) is used as the second lens. In this implementation, the flat or planar surface <NUM>' of second planoconcave lens <NUM>' is in opposing relation to the bottom lightguide surface <NUM>, and the concave surface <NUM>' of second planoconcave lens <NUM>' is the eye side of the optical combiner lens. Second medium gap <NUM>' is provided between lightguide <NUM> and planoconcave lens <NUM>' by an appropriate spacer <NUM> between lightguide <NUM> and second planoconcave lens <NUM>' - any suitable spacer structure may be used to provide the spacing between lightguide <NUM> and second planoconcave lens <NUM>' that results in second medium gap <NUM>'. The remaining features of optical combiner lens <NUM>' are as described above for optical combiner lens <NUM>, and reference numbers used with optical combiner lens <NUM> have been retained in <FIG> in the interest of continuity. Any of the variations in securing the lens/lightguide stack, any material selection considerations for optical combiner lens <NUM>, and any selection of optical powers described above, and further below, apply to this alternative implementation.

In an alternative optical combiner lens <NUM>" shown in <FIG>, a meniscus lens <NUM>" (instead of a biconcave lens or a planoconcave lens) is used as the second lens. In this implementation, the convex surface <NUM>" of second meniscus lens <NUM>" is in opposing relation to the bottom lightguide surface <NUM>, and the concave surface <NUM>" of second meniscus lens <NUM>" is the eye side of the optical combiner lens. Second medium gap <NUM>" is provided between lightguide <NUM> and meniscus lens <NUM>" by maintaining an appropriate spacing between the lightguide <NUM> and second meniscus lens <NUM>", e.g., using a lens holder <NUM> or other edge support structure or spacer, as described above for other implementations of the optical combiner lens. The remaining features of optical combiner lens <NUM>" are as described above for optical combiner lens <NUM>, and reference numbers used with optical combiner lens <NUM> have been retained in <FIG> in the interest of continuity. Any of the variations in securing the lens/lightguide stack, any material selection considerations for the optical combiner lens, and any selection of optical powers described above, and further below, apply to this alternative implementation.

In an alternative optical combiner lens <NUM>‴ shown in <FIG>, a planoconvex lens <NUM>‴ (instead of a meniscus lens) is used as the first lens. First planoconvex lens <NUM>‴ has an outer convex surface <NUM>‴ and an inner planar surface <NUM>"'. In this implementation, inner planar surface <NUM>‴ of first planoconvex lens <NUM>‴ is in opposing relation to top lightguide surface <NUM>, and outer convex surface <NUM>‴ of first planoconvex lens <NUM>‴ is the world side of the optical combiner lens. First medium gap <NUM>‴ is provided between lightguide <NUM> and planoconvex lens <NUM>‴ by an appropriate spacing maintained between inner planar surface <NUM>‴ and top lightguide surface <NUM> using lens holder <NUM> or other edge support structure or spacer, as described above for other implementations of the optical combiner lens. In this example, biconcave lens <NUM> is used as the second lens, with medium gap <NUM> formed between second biconcave lens <NUM> and bottom lightguide surface <NUM>. In other examples, a planoconcave lens or a meniscus lens may be used as second lens <NUM>. The remaining features of optical combiner lens <NUM>‴ are as described above for optical combiner <NUM>, and reference numbers used with optical combiner lens <NUM> have been retained in <FIG> in the interest of continuity. Any of the variations in securing the lens/lightguide stack, any material selection considerations of the optical combiner lens, and any selection of optical powers described above, and further below, apply to this alternative implementation.

For illustration purposes, Table <NUM> shows theoretical examples of prescriptions and corresponding lens surfaces, where the surfaces are noted in diopters. Example lens weights and edge thicknesses are also given, where the lenses are formed from a <NUM> lens blank with <NUM> edge thickness. Edge thickness would be the combined edge thicknesses of the first lens, the second lens, and the lightguide. For the examples in Table <NUM>, first lens is a meniscus lens, second lens is a biconcave lens, lightguide is a planar lightguide, and the thickness of the lightguide is <NUM>. In Table <NUM>, SPH means sphere. The examples given in Table <NUM> are for an arbitrary eyeglasses frame.

In an alternative optical combiner lens 100ʺʺ shown in <FIG>, an infrared hologram <NUM> is added to, or coupled to, or carried by, second biconcave lens <NUM>, e.g., to allow use of optical combiner lens <NUM>‴ for eye tracking and/or retinal imaging using infrared light. Infrared hologram <NUM> redirects at least a portion of infrared light incident on the hologram, where the magnitude of the portion depends on the playback efficiency of the hologram, and transmits other light, such as visible light, generally without modifying the other light. This may also be described as the infrared hologram <NUM> being responsive to infrared light and unresponsive to visible light. Infrared hologram <NUM> may be encoded, carried, embedded in or on, or otherwise generally included in a single material of holographic material, e.g., photopolymer and/or a silver halide compound. Infrared hologram <NUM> may be added, e.g., by adhering, to either of the surfaces <NUM>, <NUM> of second biconcave lens <NUM> or may even be embedded in second biconcave lens <NUM>. Since infrared hologram <NUM> is not responsive to visible light, infrared hologram <NUM> should not have any effect on light coming out of out-coupler <NUM> provided the light is in the visible range, or not within the range of wavelengths to which infrared hologram <NUM> is responsive. Where infrared hologram <NUM> is a reflection hologram, infrared hologram <NUM> will redirect infrared light incident on the eye side of the optical combiner lens <NUM>"', i.e., incident on the outer surface <NUM> of second biconcave lens <NUM>. In optical combiner lens variations that use a planoconcave lens or a meniscus lens as second lens <NUM>, the second planoconcave lens or second meniscus lens could carry infrared hologram <NUM> in the same manner described above with reference to <FIG>. Also, first lens <NUM> is shown as a meniscus lens in <FIG> but could be a planoconvex lens in other implementations.

<FIG> shows optical combiner lens <NUM> formed in the shape of an eyeglass. (Alternatively, any of the previously described optical combiner lens variations <NUM>', <NUM>", <NUM>‴, <NUM>'''' may be formed in the shape of an eyeglass. ) <FIG> shows optical combiner lens <NUM> carried by a support structure <NUM> of a wearable heads-up display (WHUD) <NUM>. For illustration purposes, support structure <NUM> is in the form of an eyeglasses frame that may be worn on a head of a subject. Support structure <NUM> as illustrated includes a front frame <NUM> and temples 198a, 198b attached to opposite sides of front frame <NUM>. In one example, optical combiner lens <NUM> is fitted into a lens mount <NUM> in front frame <NUM>. A second lens <NUM> is fitted into a lens mount <NUM> in front frame <NUM>. Lens <NUM> may be an optical combiner lens or an ordinary eyeglass. Also, lens <NUM> may or may not carry an eyeglasses prescription.

Referring to <FIG>, a display light source <NUM> (e.g., a projector, a scanning laser projector (SLP), a microdisplay, or the like) may be carried in temple 198a (also, in <FIG>). In the illustrated example, display light source <NUM> is a SLP including a light engine 204a that emits laser light and an optical scanner (e.g., scan mirror(s)) 204b to scan the laser light over a target. Display light source <NUM> emits light that is directed to in-coupler <NUM>. Light from display light source <NUM> enters lightguide <NUM> through in-coupler <NUM>, travels along lightguide <NUM> by TIR, and exits lightguide <NUM> through out-coupler <NUM>. Light exiting through out-coupler <NUM> travels through second lens <NUM>. In use, the light exiting second lens <NUM> enters the pupil of an eye <NUM> of a user wearing the wearable heads-up display, enabling the user to see a displayed image. In the setup shown in <FIG>, any of the other optical combiner variations described above may replace optical combiner <NUM>.

Although not shown in <FIG>, additional optics may be used in between display light source <NUM> and input-coupler <NUM> and/or in between in-coupler <NUM> and out-coupler <NUM> and/or in between out-coupler <NUM> and the eye of the user in order to shape the display light for viewing by the eye of the user. As an example, a prism may be used to steer light from display light source <NUM> into in-coupler <NUM> so that light is coupled into in-coupler <NUM> at the appropriate angle to encourage propagation of the light in lightguide <NUM> by TIR. Also, an exit pupil expander (EPE), e.g., a fold grating, may be arranged in an intermediate stage between input-coupler <NUM> and out-coupler <NUM> to receive light that is coupled into lightguide <NUM> by input-coupler <NUM>, expand the light, and redirect the light towards out-coupler <NUM>, where out-coupler <NUM> then couples the light out of lightguide <NUM>.

Claim 1:
An optical combiner lens, comprising:
a first lens (<NUM>);
a second lens (<NUM>);
a lightguide (<NUM>) in stack with the first lens (<NUM>) and the second lens, wherein a first medium gap (<NUM>) is defined within the stack (<NUM>) and between the first lens (<NUM>) and the lightguide (<NUM>), and wherein a second medium gap (<NUM>) is defined within the stack (<NUM>) and between the lightguide (<NUM>) and the second lens (<NUM>);
an in-coupler (<NUM>) physically coupled to the lightguide (<NUM>) and positioned to receive light into the lightguide (<NUM>); and
an out-coupler (<NUM>) physically coupled to the lightguide (<NUM>) and positioned to output light from the lightguide (<NUM>),
wherein the in-coupler (<NUM>) is physically coupled to an input area (112a) of the lightguide (<NUM>) that is not in registration with the first lens (<NUM>) and the second lens (<NUM>), and
wherein the lightguide (<NUM>) is physically coupled to the first lens (<NUM>) and the second lens (<NUM>) by an edge support structure (<NUM>) that holds the first lens (<NUM>), the lightguide (<NUM>), and the second lens (<NUM>) in a spaced apart relation in the stack (<NUM>);
characterized in that,
the edge support structure (<NUM>) is made of a transparent material, or includes an aperture or transparent section to allow light to travel to the in-coupler (<NUM>) in the input area (112a) of the lightguide (<NUM>) within the edge support structure.