CN114442318A

CN114442318A - Head-mounted perspective display and recording system guided by holographic substrate and intelligent glasses

Info

Publication number: CN114442318A
Application number: CN202110320112.5A
Authority: CN
Inventors: 费多尔·迪莫夫
Original assignee: Luminit LLC
Current assignee: Luminit LLC
Priority date: 2020-11-06
Filing date: 2021-03-25
Publication date: 2022-05-06

Abstract

Holographic substrate guided head mounted see-through displays and recording systems and smart glasses are described. The present application relates to a head mounted see-through display using a recorded substrate guided holographic sequential lens (SGHCL) and a scanning laser beam to produce an image on a diffuser or a micro display with laser illumination. The high diffraction efficiency of the volume SGHCL produces very high brightness of the virtual image.

Description

Head-mounted perspective display and recording system guided by holographic substrate and intelligent glasses

Cross Reference to Related Applications

This application claims priority from co-pending U.S. patent application No. 16/800,531, filed on 25/2/2020, which is incorporated herein by reference.

Technical Field

The present application is directed to a monochrome or full color Head Mounted Display (HMD) characterized by volumetric substrate guided holographic reflective continuous lens (SGHCL) optics comprising a scanning laser beam or a microdisplay with laser-based illumination.

Background

It is estimated that by 2025, the combined revenue from the sale of Augmented Reality (AR), Virtual Reality (VR), and smart glasses will approach $ 800 billion. Approximately half of the revenue is proportional to the hardware of the device, while optics is critical. However, despite such huge demands, such devices are still difficult to manufacture and lack quality. One reason is that conventional optical elements are limited to the laws of refraction and reflection, which require bulky custom-made optical elements that are difficult to manufacture to form a usable image in the wearer's field of view. Another reason is that the refractive optical material is heavy. Yet another reason is that current devices provide a narrow field of view. Another reason is that current devices have significant dispersion, crosstalk and degradation. Another reason is that current designs based on diffractive or holographic optics have low Diffraction Efficiencies (DE) of about only 10% to 15%. These limitations result in an unsatisfactory arrangement. Thus, there is a need for an effective solution to the problem of not being able to manufacture and provide a quality HMD, which the present disclosure addresses.

Disclosure of Invention

The present disclosure relates to a holographic substrate guided head mounted see-through display comprising: (a) an image source comprising a scanning laser beam or a microdisplay with laser-based illumination; and (b) an edge-illuminated transparent substrate; and (c) a single volume of SGHCL.

In one aspect, a holographic substrate guided see-through head mounted display comprises: (a) an image source comprising a microdisplay with laser-based illumination; (b) an edge-illuminated transparent substrate comprising angled edges or index-matched transparent prisms; and (c) a single volume holographic lens comprising a reflective SGHCL, the single volume holographic lens having an index of refraction matched to the substrate and rotated 180 ° about a vertical axis of symmetry passing through the center of the SGHCL; wherein, upon playback, the incident guided beam undergoes total internal reflection and strikes the SGHCL under bragg conditions.

In another aspect, a holographic substrate guided head mounted display has a substrate comprising a thickness of about 3mm to 6 mm. Another embodiment is where the substrate and the prism each comprise glass, quartz, acrylic plastic, polycarbonate plastic, or a mixture thereof. Yet another option is that the base plate comprises a single plate or a plurality of plates. Yet another option is that the substrate comprises edges angled at 15 ° to 25 ° or index matched prisms at 15 ° to 25 °.

In one embodiment of the holographic substrate guided head mounted display, the micro-display comprises laser illuminated Liquid Crystal On Silicon (LCOS), Digital Light Processing (DLP) or Liquid Crystal Display (LCD) of single color or RGB (full color).

In another embodiment, a holographic substrate guided head mounted display has a substrate opposite the viewer's eye that includes an anti-reflective coating. In yet another embodiment, the substrate comprises a curved shape. In yet another embodiment, the substrate comprises prescription eyeglasses. In yet another embodiment, the substrate comprises a single body or a plurality of bodies made of the same material or different materials. In another embodiment, the substrate comprises a shape comprising: rectangular, oval, circular, teardrop, hexagonal, rectangular with rounded corners, square, or mixtures thereof. In another embodiment, one or more edges of the substrate include a light absorbing coating.

In different embodiments of the holographic substrate guided head mounted display, the micro-display is directly attached to the substrate or comprises a gap with respect to the substrate.

In another embodiment of the holographic substrate guided head mounted display, the SGHCL comprises a first side and a second side, the second side being opposite the first side; and wherein, at playback, the SGHCL has a diffracted beam on a first side and a playback beam on a second side. In yet another embodiment, the SGHCL has the diffracted beam and the replay beam on the same side at replay.

In one embodiment of the holographic substrate guided head mounted display, the retrieved image comprises a monochrome or RGB (full color) image.

In another embodiment, a holographic substrate guided head mounted display includes a focused, modulated scanning laser beam and a diffuser.

Also included herein is a method of recording a volume reflection SGHCL, the method comprising: projecting the two beams onto a holographic polymer index matched to the substrate, wherein a first recording beam is directed from an edge of the substrate and converges to a first focal point and a second recording beam is a diverging beam, and wherein both beams cover the holographic polymer.

In another embodiment of a method of recording a volume reflection SGHCL, a substrate is index matched to a first rectangular block having angled edges or index matched prisms; wherein the first recording beam is directed using a long focal length lens and is directed to be at a recording spot O₁Medium focusing to converge and the second recording beam is in the plane generated by the high numerical aperture lens to recordPoint O₂Medium focus but divergence; wherein a second rectangular block is placed below the holographic polymer to avoid total internal reflection of the guided beam back from the bottom surface of the holographic polymer to avoid recording an unwanted transflector-guided holographic continuous lens; wherein the recording converging beam comprises an angle of less than or equal to about 48 ° with the substrate and the holographic polymer; wherein the reliable lead angle is greater than about 12 °; wherein the microdisplay or the focused laser beam is positioned at the equivalent focal point of the recording converging and diverging beams; wherein a cylindrical lens is used to converge the recording beam to minimize aberrations; wherein the position, tilt and focus of the cylindrical lens are adjusted to minimize aberrations; wherein the HMD image comprises a virtual image from infinity; and wherein a minimum angle of the converging beam to the holographic polymer surface comprises about 14 ° and a maximum angle of the converging beam to the holographic polymer surface comprises about 31 °, wherein the central beam has an angle of 15 ° to 25 °.

The HMD of the present application has several benefits and advantages. One benefit is that the brightness of the virtual image is very high. A second benefit is that the HMD is not subject to glare when illuminated from the front with bright sunlight or other light. Another advantage is that HMDs are small, low profile and lightweight. Yet another advantage is that there is a wide field of view (FOV) and a large exit pupil distance so that the HMD can be worn with conventional eyeglasses. Yet another advantage is an increase in DE by a factor of 8. An additional advantage is that color variations throughout the FOV are eliminated. Another advantage is that the volume SGHCL accepts a wider range of beam angles from a scanned laser beam real image or laser-based microdisplay than a conventional holographic lens based on volume holograms with a small range of acceptance angles.

Drawings

Fig. 1 is an illustration of one embodiment of a playback setup for vertical geometry of a full color HMD with SGHCL and with RGB laser illuminated microdisplays.

Fig. 2 is an illustration of an arrangement for recording a reflective RGB SGHCL HMD with one directed spherical converging beam and one spherical diverging beam.

Fig. 3 shows color mixing bins for red, green and blue laser wavelengths.

Fig. 4 shows a direct replay of reflected RGB SGHCL, where the diffracted beam is on the same side of the substrate as the replay beam.

Fig. 5 shows a diagram of a reflected RGB SGHCL being played back after an incident guided beam undergoes total internal reflection, with a diffracted beam on the opposite side of the substrate from the playback beam.

Fig. 6 is a photograph of an example setup for recording a reflective RGB SGHCL with two spherical beams, where neither a holographic diffuser nor a cylindrical lens is used in recording the reflective SGHCL.

Fig. 7 is a photograph of an example setup for playback without using a holographic diffuser and without using a cylindrical lens when recording a reflective SGHCL.

Fig. 8 shows a graph of aberrations of a virtual image retrieved at the time of playback when a cylindrical lens is not used at the time of recording the SGHCL.

Fig. 9 is an illustration of an optimized recording setup for a reflective RGB SGHCL HMD with one guided beam passing through an additional cylindrical lens to reduce astigmatism and a second beam that is a spherical diverging beam.

Fig. 10 shows a photograph of an example of a virtual image retrieved by an HMD with an SGHCL recorded with a lenticular lens when using a microdisplay with a conventional diffuser.

Fig. 11 is a diagram of one embodiment of smart glasses with an SGHCL and prescription optics.

Detailed Description

The present disclosure relates to HMDs with Thin Holographic Component (THC) based volumetric (thick) SGHCL and scanning laser beams or microdisplays with laser-based illumination. A micro display may be used or may be replaced by a focused modulated scanning laser beam that draws a real image of high resolution on the diffuser. The HMD may be full color (RGB) or monochromatic, with a single laser wavelength input for monochromatic and a three color (RGB) laser beam input for full color.

In one embodiment, a holographic substrate guided head mounted see-through display includes: (a) an image source comprising a focused, modulated, scanned laser beam drawing a real image on a diffuser or a microdisplay with laser-based illumination placed in the diffuser plane; (b) an edge-illuminated transparent substrate; and (c) single volume reflection SGHCL. SGHCL is index matched to the substrate.

In another embodiment, a holographic substrate guided head mounted see-through display includes: (a) an image source comprising a focused modulated scanning laser beam drawing a real image on a diffuser or a micro-display with laser-based illumination placed at the plane; (b) an edge-illuminated transparent substrate comprising angled edges or index-matched transparent prisms; and (c) a volume holographic continuous lens comprising a reflective Substrate Guided Holographic Continuous Lens (SGHCL) having a refractive index matched to the substrate and rotated 180 ° about a vertical symmetry axis passing through the center of the SGHCL; wherein, upon playback, the incident guided beam undergoes total internal reflection and strikes the SGHCL under bragg conditions. In this embodiment, diffraction to the eye occurs on the substrate side opposite to the substrate side near the microdisplay.

Fig. 1 shows an example of a playback setup 10 for an HMD with a volumetric RGB SGHCL with a micro-display 12, the micro-display 12 with vertical geometry of the laser-based RGB illumination. The microdisplay 12 can be a single or full color laser illuminated front emitting LCOS, DLP, or LCD with laser backlight. The substrate 18 is completely transparent to provide a wide see-through FOV and may be made of a variety of materials, such as glass, quartz, acrylic plastic, polycarbonate plastic, or mixtures thereof. The base plate 18 may be a single plate or multiple plates and may have various shapes including rectangular, oval, circular, teardrop, hexagonal, rectangular with rounded corners, square, or a mixture thereof. The side of the substrate 18 opposite the eye may be coated with an anti-reflective (AR) coating to improve perspective transmission. As in prescription glasses, the substrate 18 may also be curved to correct poor vision. A thin layer of concave glass with a low refractive index may be attached to the bottom of the substrate 18 to make it compatible with prescription glasses. For an SGHCL 16 with n 1.49, the refractive index of the layer should be n 1.35 to produce Total Internal Reflection (TIR) at 25 °. The thickness of the substrate 18 may be in the range of about 3mm to 6mm, but may be thicker if desired. Substrate 18 may be made of a single unitary body or may include multiple bodies made of the same or different transparent materials. Some edges of the substrate 18 may also be coated with a light absorbing coating, such as a black paint. Substrate 18 may also contain a colorant or dye.

Substrate 18 may be angled at one end, or may also include a wedge prism 14 that is index matched to the end of substrate 18 upon playback. The angled edges or attached wedge prisms 14 serve to minimize aberrations of the refracted beam from air in the glass and may vary between 15 ° and 25 ° depending on the playback angle, the thickness of the substrate 18, and the size of the SGHCL 16. The prism 14 may be a triangular prism or a trapezoidal prism. Prism 14 may be made from a variety of materials, such as glass, quartz, acrylic plastic, polycarbonate plastic, or mixtures thereof. Prism 14 may be the same material and/or composition as substrate 18, or may be different from substrate 18.

The RGB laser illuminated microdisplay 12 is positioned parallel to the angled edge of the substrate 18 or the surface of the wedge prism 14 so that the central beam from the microdisplay 12 is perpendicular to the substrate edge 18, thereby also minimizing refractive aberrations. The microdisplay 12 may be attached directly to the substrate 18 or there may be a gap between the microdisplay 12 and the substrate 18. The gap allows adjustment of the microdisplay 12 along the optical axis to focus the virtual image and to change its apparent image plane. In another embodiment, the microdisplay 12 may be a monochrome microdisplay.

The RGB SGHCL 16 is laminated to the surface of the substrate 18 facing the viewer's eye. The SGHCL 16 may be covered with a thin layer of about 100um of glass for protection, and the glass may be AR coated to improve transmission. The playback geometry with microdisplay 12 on top of substrate 18 utilizes high definition multimedia interface (HMDI) resolution with an image aspect ratio of 16: 9. Positioned as shown, this is associated with a substrate 18 thickness of 3mm and a micro-display 12 having dimensions of 5.16mm x 3 mm. The reflective volume SGHCL is used because its angular selectivity is much lower than that of the transmissive volume hologram.

The FOV of an HMD with SGHCL may be much larger than that of an HMD with conventional SGH optics. Also, because only one hologram is used, an RGB HMD with SGHCL is much smaller and lighter than an RGB HMD with a conventional SGH. The HMD may be monochrome or full color. Further, the HMD may be monocular, binocular monocular, or binocular. When illuminated from the front, HMDs with SGHCL optics do not suffer from glare, as diffracted light couples into the substrate and does not reach the eye. The reflective SGHCL in an RGB HMD can be used as transmission if rotated 180 °, while retaining the advantages of a reflective hologram, and providing design flexibility and a larger exit-pupil distance, so that conventional glasses can be worn under the HMD. Furthermore, the DE can be increased here by a factor of up to about 8 times higher. Furthermore, due to the high DE, there is no color shift in the FOV and low power consumption.

FIG. 2 shows a recording head for recording a dot O₁And recording point O₂Of one embodiment of a reflective RGB SGHCL, with two spherical beams. Convergent focusing of a recording RGB beam at point O using a long focusing lens 32₁. Another RGB beam is emitted at a point O generated by a lens 44 with a large numerical aperture (F # < 1)₂Medium focus and divergence to produce a large FOV. Both beams should be covered with a thin holographic polymer 34, the holographic polymer 34 being laminated to a glass substrate 40 index matched to a glass block 42. For convenience and stability in hologram recording, a glass substrate of about 1mm may be used, and may be eliminated at the time of playback. A 15 ° to 25 ° wedge prism 38 is attached to the glass block 42 on the side of the glass block 42 adjacent to the side to which the substrate 40 is attached. In one embodiment, a 20 wedge prism is used. A second glass block 36 is placed below the holographic polymer 34 to avoid the beam reflecting back from the bottom surface of the holographic polymer 34. To undergo TIR and be directed, the recording beam may be at an angle no greater than 48 ° from the surface of glass substrate 40 with holographic polymer 34 laminated therein, since the TIR angle at the boundary between air and glass is about 42 °. With lamination of holographic polymers34 the minimum angle of the surface of the glass substrate 40 should not be too small (<12 deg.) because even a slight difference in refractive index between glass and holographic polymer can make the propagation of the shallow guided beam problematic, especially considering that the refractive index of the holographic material is slightly different (Δ n 0.03) before and after recording. The guiding beam should propagate reliably during both recording and playback. For holographic materials using an average refractive index n-1.48, a reliable lead angle should be>12 deg. In this example, the central beam of the spherical guide beam is at an angle of 20 ° to the holographic polymer surface and a wedge-shaped 20 ° prism 38 attached to a glass block 42 is used to minimize the aberration of recording the spherical beam refracted into the glass from air. The minimum and maximum angles in the medium of the converging bundle are 14 ° and 26 °, respectively. The angle α of the diverging beam produced using the large Numerical Aperture (NA) lens 44 is selected to produce the desired FOV upon playback.

Fig. 3 shows a color mixing box for generating RGB laser beams for hologram recording. The color mixing box contains various mirrors that reflect and combine the colored laser light. As described above, the light will be directed to lens 32 and lens 44. After the reflection SGHCL is recorded and processed, it will be played back, as shown in fig. 4 and 5.

Fig. 4 shows a recorded reflective RGB SGHCL setup 50 for direct playback. A setup includes a microdisplay 52, a glass substrate 54, and a hologram 56 attached to the glass substrate 54. At playback, the diffracted beam is on the same side of the glass substrate 54 as the playback beam from the microdisplay 52 beam, which microdisplay 52 beam strikes the thick reflective SGHCL under bragg conditions and is diffracted to the viewer's eye.

In fig. 5, the playback setup 70 includes a prescription glasses male portion 72, a micro display 74, and a glass substrate 80, with the micro display 74 and prescription glasses 72 attached to the glass substrate 80. The micro display 74 is attached to one side of a glass substrate 80. The hologram 78 is attached to a surface of the glass substrate 80 that is different from the surface to which the prescription glasses 72 are attached. The concave portion 76 of the prescription glasses having a low refractive index is also attached to the bottom of the glass substrate 80. The micro-display 74 and the viewer's eye are on opposite sides of the hologram 78. The reflective RGB SGHCL is rotated 180 ° around an axis of symmetry passing through the center of the SGHCL and perpendicular to the sides of the SGHCL to operate as transmissive. On the left side of the figure is an enlarged segment showing one ray of the playback beam undergoing TIR and reflecting from the SGHCL stripe. The playback guided beams impinge on the SGHCL, which is not at bragg, undergo total internal reflection, then they are at bragg and efficiently diffract down to the eye. At playback, the SGHCL has a diffracted beam and a playback beam on different sides of the SGHCL. Here, the reflection SGHCL is used as transmission. Furthermore, the exit pupil distance is increased by a few millimeters, almost the thickness of the glass substrate divided by the glass index of refraction. Reflective SGHCL helps to increase the FOV due to higher wavelength selectivity compared to transmission holograms.

Fig. 6 shows a picture of a setup for recording a reflective monochromatic SGHCL with a 532nm laser beam. The schematic diagram of fig. 2 was followed to construct a monochrome recording holographic setup. Holographic polymer 1 for recording SGHCL was laminated to a 1mm substrate 2, which substrate 2 was index matched to a glass block 3. A 20 deg. prism 5 is placed at one end of the glass block 3. The glass block 4 is placed opposite the holographic polymer 1 to exclude TIR from the converging guide beams on the outside of the hologram and to avoid recording unwanted transmissive substrate-guided holograms.

For playback, a laser beam phase conjugate to the recording converging beam is used. And the recording spot O shown in FIG. 2₁In contrast, the microdisplay is placed closer to the recorded SGHCL. By positioning the microdisplay closer to the SGHCL, all field points of the microdisplay conform to the recorded SGHCL under bragg conditions, since the entire area of the microdisplay positioned in the vertical direction is covered by the recording beam. Due to the distance D from₁To this offset closer to the SGHCL, the angular range of the beam from the field point in the bragg degradation direction of the microdisplay that is accepted by the thick hologram increases. In addition, when converging to the point O₁Beam and slave point O₂When the divergent beams interfere, the retrieved beam becomes collimated and diffracted on the resulting fringes. This is a significant advantage of a continuous lens compared to conventional holographic lenses, which typically record with one collimated beam and another spherical beam. To create a collimated retrieved beam, the microdisplay is placed at a distance SDistance F of GHCL_EQVHere, the following formula (1) is satisfied:

1/F_EQV＝1/D₁+1/D₂ (1)

wherein D is₁And D₂Shown in FIG. 2, and F_EQVIs the equivalent focus of the recorded SGHCL. The enlarged virtual image of the microdisplay comes from infinity, where each point of the virtual image is formed by a collimated beam. When playing back the point source from O₁To the equivalent focal point F_EQVIn position (d), a collimated beam is produced.

Depending on the aspect ratio of the microdisplay image, the microdisplay may be placed at the horizontal or vertical edge of the glass substrate that conforms to the SGHCL recording bragg plane. For HDMI resolution 16(H) in which the vertical image size is almost 1/2 times the horizontal size: 9(V) placing the microdisplay on top of the glass substrate. This will ensure a maximum vertical FOV (based on bragg angle selectivity) and a rather thin substrate (based on minimum guiding angle). SGHCL does not significantly limit the horizontal FOV because the angular selectivity is much lower in the non-bragg degenerate direction. Depending on the geometry of the HMD and the necessity to adjust the focus by moving the micro-display, the micro-display may be attached directly to the waveguide as shown in fig. 4 and 5, or there may be a gap between the micro-display and the waveguide as shown in fig. 1, allowing for dynamic adjustment of the focus.

Fig. 7 is a picture of a playback setup based on the geometry shown in fig. 1 for testing the recorded SGHCL using USAF resolution test targets with different spatial frequencies of black and white line pairs. A glass substrate 9 with SGHCL 8 is shown, wherein a 20 ° wedge prism 10 is attached to the substrate 9. The holder 11 is attached to the wedge prism 10. The beam illuminates the USAF target and travels through the wedge into the glass substrate and is coupled out through the SGHCL, where the acquired diffracted beam is seen by the viewer's eye and can be captured with a camera.

However, the retrieved virtual image is significantly distorted. Fig. 8 shows aberrations at the time of playback 90 in the case where no cylindrical lens is used at the time of recording of the SGHCL 96. Due to the significant tilt of the SGHCL 96 relative to the incidence of the beam from the micro-display 94, the beam diffraction from field points close to the SGHCL 96 is divergent, while the beam diffraction from field points far from the SGHCL 96 is convergent. These aberrations are corrected by adding a cylindrical lens to the recording setup 100, as shown in fig. 9.

FIG. 9 shows a recording head for recording dots O₁And recording point O₂Example of a recording system 100 with two beams for one implementation of a reflective RGB SGHCL. A recording RGB beam is focused on a point O in a vertical plane using a long-focus spherical achromat 106₁The lens 106 has a collimated beam 102 that enters and passes through the cylindrical lens 104 unchanged in the plane. While in the horizontal plane the beam is focused at point O₁One position at which the cylindrical lens beam is focused in the horizontal plane is previously indicated by the vertical dashed line in fig. 9. This arrangement eliminates the presence of astigmatism. Another RGB beam is emitted at a point O generated by a lens 110 with a large numerical aperture (F # < 1)₂Medium focus and divergence to produce a large FOV. In one embodiment, the lens is 40X and 0.65 Numerical Aperture (NA). Both beams should be covered with a thin holographic polymer 108 that is laminated to a glass substrate 116 index matched to the glass block 120. For convenience and stability in hologram recording, a glass substrate of about 1mm may be used, and may be removed at the time of playback. A 15 ° to 25 ° wedge prism 114 is attached to the glass block 120 on the side of the glass block 120 adjacent to the side to which the substrate 116 is attached. In one embodiment, a 20 wedge prism is used to minimize aberrations recording the refraction of the spherical beam from air into the glass. A second glass piece 122 is placed below the holographic polymer 108 to avoid the beam reflecting back from the bottom surface of the holographic polymer 108. To undergo TIR and be directed, the recording beam may be at an angle of no greater than 48 ° from the surface of glass substrate 116 in which holographic polymer 108 is laminated, since the TIR angle of the boundary between air and glass is about 42 °. The minimum beam angle with the surface of the glass substrate to which holographic polymer 108 is laminated should not be too small (<12 deg.) because even a slight difference in refractive index between glass and holographic polymer will resultPropagation of the shallow guided beam is made problematic, especially considering that the refractive index of the holographic material is slightly different (Δ n-0.03) before and after recording. The guide beam should propagate reliably during both recording and playback. For holographic materials using an average refractive index n-1.48, a reliable lead angle should be>12 deg. In this example, the central beam of the spherical guide beam is at an angle of 20 ° to the holographic polymer surface, and a wedge-shaped 20 ° prism 114 is attached to a glass block 120. The minimum and maximum angles in the medium of the converging beam are 14 ° and 26 °, respectively. The angle alpha of the diverging beam produced using the large NA lens 110 is selected to produce the desired FOV upon playback. The position of the microdisplay at playback is shown in dashed lines.

An example of a virtual image captured with a camera employing auto-correction functionality, retrieved by an HMD with an SGHCL, is shown in fig. 10. Existing aberrations can be eliminated by implementing a machined hologram that produces the desired pre-distorted recorded wavefront, and by pre-distorting the microdisplay image. The estimated FOV of the virtual image is >40 °, >40 °, eye box (eyebox) >10mm, and exit pupil distance >20mm, which is appropriate for an HMD. This is an example of the maximum FOV achieved in an HMD using a single hologram. At the time of playback, since the hologram shrinks in the post-exposure process, the laser wavelength should be adjusted, and the playback wavelength in the bragg should be a few nanometers short. Some of the image blurriness in fig. 10 may be from camera focus inaccuracy on the virtual image, but significant reduction in virtual image resolution is caused by the granularity of the diffuser used to create the eye box or Exit Pupil Expansion (EPE). By implementing a diffuser with a smaller particle size, the resolution can be significantly improved.

Fig. 11 shows an example of a partial view of smart glasses 160 using an SGHCL. The scanning focused laser beam is characterized by being located F away from SGHCL 164_EQVA real image in the plane of the distance diffuser 174. In another embodiment, the laser beam is focused to a diffuser positioned at an equivalent focus point from SGHCL 164 and attached directly to an angled edge of the substrate or positioned at a distance of a few millimeters for better focusing. The display comprises a high refractive index substrateThe index substrate is integrated with the prescription eyewear optics 162 and the absorbing layer 176 to prevent leakage of the laser beam into the air and to couple light from the air into the glass substrate and then out to the eye as unwanted glare. SGHCL 164 is molded inside prescription glass lens 162 for use by a visually impaired user. Control electronics, a miniature three-color laser projector, an ear-piece, and a battery 172 are contained within the side arm 170 of the smart glasses 160. The scanner 168 is located near a laser included in the battery 172 and is not separately shown here. Within the side arm 170 there is a turning mirror 166 adjacent the scanner 168, both of which are contained alongside the prescription glass lens 162. Turning mirror 166 redirects the laser beam to diffuser 174 so it strikes diffuser 174 at an angle that minimizes aberrations (typically close to normal) and enters the substrate as a guided beam that strikes SGHCL 164 at a bragg angle. The refractive indices of the bulk of the SGHCL 164 and the prescription glass lens 162 have a difference to satisfy the TIR condition at the boundary. These smart glasses 160 may be monocular, binocular monocular, or binocular. The smart glasses will comfortably fit on the face with a weight of less than about 100 grams as conventional prescription glasses. The entire assembly substrate/prescription optics/SGHCL is highly transparent. For maximum transparency, the outer side may be anti-reflection coated or colored. Only the right side of the frame is depicted in fig. 11. For a binocular HMD, the left side is the depicted right side mirror. For monocular HMDs, the left side has no electronics, laser projector and hologram, and contains only a battery, which would reduce the overall weight of the glasses.

Various aspects of the invention may be implemented as follows:

1. a holographic substrate guided see-through head mounted display comprising:

(a) an image source comprising a scanning laser beam or a microdisplay with laser illumination;

(b) an edge-illuminated transparent substrate, and;

(c) a single volume substrate guided holographic continuous lens.

2. The holographic substrate guided head mounted see-through display of claim 1, wherein:

(a) the image source comprises a microdisplay with laser-based illumination;

(b) the edge-illuminated transparent substrate comprises an angled edge or index-matched transparent prism, and;

(c) the single volume substrate guided holographic continuous lens comprises a reflective substrate guided holographic continuous lens index matched to the substrate and rotated 180 ° about a vertical axis of symmetry passing through the center of the substrate guided holographic continuous lens;

wherein, upon playback, the incident guided beam undergoes total internal reflection and strikes the substrate-guided holographic continuous lens under Bragg conditions.

3. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises a thickness of about 3mm to 6 mm.

4. The holographic substrate guided head mounted see-through display of claim 2, wherein the substrate and the prism each comprise glass, quartz, acrylic plastic, polycarbonate plastic, or a mixture thereof.

5. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises a single plate or multiple plates.

6. The holographic substrate guided head mounted see-through display of 1, wherein the substrate comprises an edge angled at 15-25 ° or an index matched prism at 15-25 °.

7. The holographic substrate guided head mounted see-through display of 1, wherein the microdisplay comprises a laser illuminated monochrome or RGB (full color) liquid crystal on silicon microdisplay, digital light processing microdisplay, or liquid crystal display.

8. The holographic substrate guided head mounted see-through display of claim 1, wherein a side of the substrate opposite the eye of the viewer comprises an anti-reflective coating.

9. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises a curved shape.

10. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises prescription glasses.

11. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises a single body or multiple bodies made of the same material or different materials.

12. The holographic substrate guided head mounted see-through display of claim 1, wherein one or more edges of the substrate comprise a light absorbing coating.

13. The holographic substrate guided see-through head mounted display of claim 1, wherein the micro-display is directly attached to the substrate or comprises a gap relative to the substrate.

14. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate guided holographic continuous lens comprises a first side and a second side, the second side opposite the first side; and wherein, upon replay, the substrate-guided holographic sequential lens has a diffracted beam on the first side and a replay beam on the second side.

15. The holographic substrate-guided see-through head-mounted display of claim 1, wherein, upon playback, the substrate-guided holographic sequential lens has a diffracted beam and a playback beam on the same side.

16. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises a shape comprising: rectangular, oval, circular, teardrop, hexagonal, rectangular with rounded corners, square, or mixtures thereof.

17. The holographic substrate guided head mounted see-through display of claim 1, wherein the retrieved image comprises a monochrome image or an RGB (full color) image.

18. The holographic substrate guided head mounted see-through display of claim 1, comprising a focused, modulated scanning laser beam and a diffuser.

19. A method of recording a volume reflective substrate-guided holographic continuous lens, the method comprising: projecting two beams onto a holographic polymer having an index of refraction matched to a substrate, wherein a first recording beam is directed from an edge of the substrate and converges to a first focal point and a second recording beam is a diverging beam, and wherein both beams overlay the holographic polymer.

20. The method of recording the volume reflective substrate-guided holographic continuous lens of 19, wherein the substrate is index matched to a first rectangular block having angled edges or index matched prisms;

wherein the first recording beam is directed using a long focal length lens and converges with a focus in a recording point O1, and the second recording beam diverges with a focus point O2 in a plane produced by the high numerical aperture lens;

wherein a second rectangular block is placed below the holographic polymer to avoid total internal reflection of the guided beam back from the bottom surface of the holographic polymer to avoid recording an unwanted transmissive substrate-guided holographic continuous lens;

wherein the recording converging beam comprises an angle of less than or equal to about 48 ° with the substrate and the holographic polymer;

wherein the reliable lead angle is greater than about 12 °;

wherein a micro-display or a focused laser beam is positioned at an equivalent focal point of the recording converging beam and the diverging beam;

wherein a cylindrical lens is used for said converging recording beam to minimize aberrations;

wherein the position, tilt, and focus of the cylindrical lens are adjusted to minimize aberrations;

wherein the HMD image comprises a virtual image from infinity; and

wherein a minimum angle of the converging beam to the holographic polymer surface comprises about 14 ° and a maximum angle of the converging beam to the holographic polymer surface comprises about 31 °, wherein the central beam has an angle of 15 ° to 25 °.

Alternative embodiments of the subject matter of this application will be apparent to those of ordinary skill in the art to which this invention pertains without departing from its spirit and scope. It should be understood that no limitation with respect to the specific embodiments illustrated herein is intended or should be inferred.

Claims

1. A holographic substrate guided see-through head mounted display comprising:

(b) an edge-illuminated transparent substrate;

(c) a single volume substrate guided holographic continuous lens; and

(d) a diffuser;

wherein the scanning laser beam produces an image on the diffuser, and

(a) the image source comprises a microdisplay with laser-based illumination;

(b) the edge-illuminated transparent substrate comprises angled edges or index-matched transparent prisms; and

(c) the single volume substrate guided holographic continuous lens comprises a reflective substrate guided holographic continuous lens having a refractive index matched to the substrate and rotated 180 ° about a vertical axis of symmetry passing through the center of the substrate guided holographic continuous lens.

6. The holographic substrate guided head mounted see-through display of claim 1, wherein the substrate comprises an edge angled at 15 ° -25 ° or an index matched prism at 15 ° -25 °.

7. The holographic substrate guided head mounted see-through display of claim 1, wherein the microdisplay comprises a laser illuminated monochrome or RGB full color liquid crystal on silicon microdisplay, a digital light processing microdisplay, or a liquid crystal display.

8. The holographic substrate guided head mounted see-through display of claim 1, wherein a side of the substrate opposite the viewer's eye comprises an anti-reflective coating.

13. The holographic substrate guided head mounted see-through display of claim 1, wherein the microdisplay is directly attached to the substrate or comprises a gap relative to the substrate.

15. The holographic substrate-guided head mounted see-through display of claim 1, wherein, upon playback, the substrate-guided holographic sequential lens has a diffracted beam and a playback beam on a same side.

17. The holographic substrate guided head mounted see-through display of claim 1, wherein the retrieved image comprises a monochrome image or an RGB full-color image.

20. The method of recording a volume reflective substrate guided holographic continuous lens of claim 19, wherein the substrate is index matched to a first rectangular block having angled edges or index matched prisms;

wherein the first recording beam is directed using a long focal length lens and is directed to be at a recording spot O₁Medium focus, and the second recording beam with a focal point O in the plane created by the high numerical aperture lens₂Divergence;

wherein the reliable lead angle is greater than about 12 °;

wherein the HMD image comprises a virtual image from infinity; and

21. A recording system for a reflective RGB substrate guided holographic sequential lens, comprising:

a) a glass substrate;

b) a thin holographic polymer laminated to the glass substrate;

c) a first glass block attached to the holographic polymer, wherein the first glass block has an index of refraction matching the glass substrate;

d) a wedge prism attached to the first glass piece on a side of the first glass piece adjacent to the glass substrate;

e) a long focal length spherical achromatic lens attached to the wedge prism;

f) a cylindrical lens in the vicinity of the spherical achromatic lens;

g) a second glass block attached to the glass substrate;

h) a lens with a large numerical aperture in the vicinity of the second glass block; and

i) two collimated RGB recording beams, wherein the first recording beam is brought to point O in the vertical plane using said long focal length spherical achromat₁Medium focus to converge, which eliminates astigmatism; wherein the second RGB recording beam is generated at O generated by lens with large numerical aperture₂The points are focused and divergent.

22. A smart eyewear comprising:

a) a frame having two side arms;

b) a prescription lens having an absorbing layer on one side;

c) a battery within the side arm;

d) an earpiece within the side arm;

e) a laser projector located within the side arm for projecting a laser beam;

f) a scanner within the side arm;

g) a steering mirror within the frame for redirecting a path of the laser beam;

h) a diffuser adjacent to the prescription lens; and

i) a substrate-guided holographic continuous lens integrated with the prescription lens;

wherein the diffuser with the image is used as an image source.