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WO2024229533A1 - Procédés d'impression 3d et guides de lumière fabriqués à partir de ceux-ci - Google Patents

Procédés d'impression 3d et guides de lumière fabriqués à partir de ceux-ci Download PDF

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Publication number
WO2024229533A1
WO2024229533A1 PCT/AU2024/050464 AU2024050464W WO2024229533A1 WO 2024229533 A1 WO2024229533 A1 WO 2024229533A1 AU 2024050464 W AU2024050464 W AU 2024050464W WO 2024229533 A1 WO2024229533 A1 WO 2024229533A1
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Prior art keywords
ultra
printed
transparent liquid
base structure
liquid resin
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PCT/AU2024/050464
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English (en)
Inventor
Ranjith Rajasekharan UNNITHAN
Younger Wei-Young LIANG
Dechuan SUN
Gregory TANYI
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Kdh Advanced Research Pty Ltd
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Kdh Advanced Research Pty Ltd
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Priority claimed from AU2023901422A external-priority patent/AU2023901422A0/en
Application filed by Kdh Advanced Research Pty Ltd filed Critical Kdh Advanced Research Pty Ltd
Priority to AU2024268188A priority Critical patent/AU2024268188A1/en
Publication of WO2024229533A1 publication Critical patent/WO2024229533A1/fr
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00663—Production of light guides
    • B29D11/00682—Production of light guides with a refractive index gradient
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00663—Production of light guides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/10—Formation of a green body
    • B22F10/12—Formation of a green body by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/003—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
    • B29C64/129—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/188—Processes of additive manufacturing involving additional operations performed on the added layers, e.g. smoothing, grinding or thickness control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00009—Production of simple or compound lenses
    • B29D11/00432—Auxiliary operations, e.g. machines for filling the moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C39/10—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. casting around inserts or for coating articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
    • B29K2033/04—Polymers of esters
    • B29K2033/08—Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
    • B29K2033/04—Polymers of esters
    • B29K2033/12—Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2063/00—Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
    • B29K2995/0026—Transparent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0094—Geometrical properties
    • B29K2995/0096—Dimensional stability
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00—Optical elements, e.g. lenses, prisms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00—Optical elements, e.g. lenses, prisms
    • B29L2011/0075—Light guides, optical cables
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B27/0103—Head-up displays characterised by optical features comprising holographic elements
    • G02B2027/0109—Head-up displays characterised by optical features comprising holographic elements comprising details concerning the making of holograms
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses

Definitions

  • the present invention relates, in general terms, to 3D printing methods and light guide optical elements made therefrom.
  • a light guide optical element is an optical waveguide that guides electromagnetic waves in the optical spectrum from a source to the eyes of a user.
  • the LOE may be used for augmented reality display.
  • Augmented reality (AR.) display technology enables users to perceive a virtual image overlaid onto the real world AR integrates and overlays virtual information onto the user's physical world in real-time.
  • Optical see-through near-eye displays are frequently utilized in AR display systems, where light guide optical elements (LOEs) are generally employed to direct the light emanating from the display panel towards the user's eye.
  • LOEs light guide optical elements
  • AR augmented reality
  • optical waveguide or combiner One of the key components in near-eye displays for AR applications is an optical waveguide or combiner.
  • the commercially available optical combiners can be broadly categorized into two major types based on their working principle: geometric and diffractive.
  • the geometric waveguide structure was first proposed by Lumus and has undergone continuous optimization over the past twenty years. In this approach, incident light first enters the waveguide through a reflective surface. After undergoing multiple rounds of total internal reflection, the light encounters a "semi-transmissive semi-reflective" mirror array, which couples the light out.
  • the diffractive waveguide structure utilizes diffractive optical elements such as surface relief gratings or volume holographic gratings to couple the light into and out of the waveguide.
  • Diffractive waveguide technology relies on the deposition of a thin film on glass substrates, eliminating the need for glass slicing and bonding processes used in fabricating geometric waveguides. This provides advantages in terms of flexibility in design and production.
  • a notable drawback is the presence of chromatic aberration or the appearance of the rainbow effect.
  • diffractive waveguides may have limitations in their field of view.
  • LOEs Traditional manufacturing methods for LOEs are costly, time-intensive, not possible to make curved or any other shape and often result in poor image quality.
  • the first method entails the deposition of numerous layers of materials exhibiting varying refractive indices onto a glass surface via techniques such as photolithography, physical vapor deposition, and electron-beam evaporation, then go through a layer-by-layer lamination, cutting, and further optical or air bonding process to make.
  • the second method traditionally depends on injection molding or hot embossing, which are difficult for mass production due to their time-intensive and costly nature.
  • these fabrication techniques are prone to insufficiencies in precision and uniformity across any microstructure used, which may result in the deterioration of the displayed image quality.
  • the present disclosure provides a method of 3D printing a light guide optical element, comprising: a) 3D printing a base structure using at least one ultra-transparent liquid resin, the base structure comprising a first surface and at least one holding means formed at a second surface opposite to the first surface and angled relative to the first surface; b) contacting at least one semitransparent beam splitter to the at least one holding means; and c) contacting the at least one ultra-transparent liquid resin over the at least one semitransparent beam splitter and curing the at least one ultra-transparent liquid resin in order to form the light guide optical element.
  • the base structure is 3D printed on a substrate.
  • step a) comprises depositing and at least partially curing the at least one ultra-transparent liquid resin in a slice-by-slice manner.
  • the base structure is 3D printed using liquid crystal display (LCD) 3D printing.
  • LCD liquid crystal display
  • step a) comprises varying a refractive index of the at least one ultra-transparent liquid resin such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice. This allows for light path compensation in cases where the total internal reflected light path is shifted by curvature or thickness changes induced by, for example, bending the light guide optical element.
  • step a) comprises at least partially curing the at least one 3D printed slice of the base structure under different conditions relative to the adjacent 3D printed slice.
  • the at least one 3D printed slice is at least partially cured under a pattern of light which is different relative to the adjacent 3D printed slice.
  • the at least one 3D printed slice is at least partially cured under a light intensity which is different relative to the adjacent 3D printed slice.
  • step a) comprises 3D printing the base structure using a second ultra-transparent liquid resin having a different refractive index such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • step a) comprises 3D printing the base structure using a mixture of the at least one ultra-transparent liquid resin and a second ultra- transparent liquid resin having a different refractive index such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • step a) comprises: i) 3D printing a slice of the base structure; ii) mixing a portion of a second ultra-transparent liquid resin to the at least one ultra-transparent liquid resin; iii) 3D printing a subsequent slice of the base structure; and iv) iteratively repeating step ii) and iii) until the base structure is formed.
  • the difference in refractive index between the 3D printed slices is about 0.001 to about 0.1.
  • the ultra-transparent liquid resin is a UV curable resin. In some embodiments, the ultra-transparent liquid resin is an acrylic based resin.
  • step a) is performed at an ambient temperature, or preferably at about 20 °C to about 40 °C.
  • the ultra-transparent liquid resin is characterised by a viscosity of about 400 MPa to about 700 MPa, or preferably about 450 MPa to about 600 MPa.
  • the ultra-transparent liquid resin is characterised by a volume shrinkage of less than 8%, or preferably less than 1%.
  • the 3D printing is further performed in the presence of a release liner and/or a hydrophobic material.
  • the at least one holding means is a slope cut into the second surface of the base structure.
  • the at least one holding means is angled at about 20 ° to about 40 °.
  • the at least one holding means is 3 holding means, and the at least one semitransparent beam splitter is 3 semitransparent beam splitters.
  • the at least one semitransparent beam splitter is selected from a dielectric reflector, metal reflector or a combination thereof.
  • the at least one semitransparent beam splitter is characterised by a transparency of at least 85%. In some embodiments, the at least one semitransparent beam splitter is characterised by a reflection ratio of about 8% to about 20%, or preferably about 10%.
  • the semitransparent beam splitter is characterised by root mean square (RMS) roughness of about 1.1 nm to about 1.8 nm.
  • RMS root mean square
  • step c) comprises immersing the 3D printed base structure in a tank comprising ultra-transparent liquid resin, and immersing the at least one semitransparent beam splitter in the tank comprising ultra- transparent liquid resin such that the at least one semitransparent beam splitter contacts the holding means of the base structure.
  • the method further comprises a step of separately 3D printing a top structure, the top structure comprises a third surface and a fourth surface opposite the third surface, wherein the fourth surface comprises a complementary morphology relative to second surface of the base structure and the at least one semitransparent beam splitter.
  • the method further comprises a step of mating the base structure and the at least one semitransparent beam splitter with the top structure to form the light guide optical element.
  • the base structure and the at least one semitransparent beam splitter are mated and cured with the top structure in the tank comprising ultra-transparent liquid resin.
  • step c) comprises contacting a transparent substrate and the at least one ultra-transparent liquid resin over the holding means and the second surface of the base structure to form a covered recess, curing the at least one ultra-transparent liquid resin such that the transparent substrate is adhered to the second surface, and filling the covered recess with a transparent liquid to form the light guide optical element.
  • the transparent liquid is characterised by a refractive index of about 1.4 to about 1.8.
  • the transparent liquid is silicone oil, mineral oil, polydimethylsiloxane (PDMS), or a combination thereof.
  • step c) comprises 3D printing the ultra-transparent liquid resin over the at least one semitransparent beam splitter. In some embodiments, step c) comprises depositing and at least partially curing the ultra-transparent liquid resin in a slice-by-slice manner. In this way, any gap or space adjacent to the at least one semitransparent beam splitter may be filled up in a layer-by-layer manner.
  • step c) comprises varying a refractive index of the ultra- transparent liquid resin such that at least one 3D printed slice has a different refractive index relative to an adjacent 3D printed slice.
  • the base structure further comprises a prism structure at an end thereof.
  • the prism is a triangular prism positioned at an angle of about 40° to about 60° relative to the first surface of the base structure.
  • the method further comprises a step after step a) of cleaning and further curing the base structure of step a).
  • the method further comprises varying a refractive index of the light guide optical element such that at least one 3D printed slice of the light guide optical element has a different refractive index relative to an adjacent 3D printed slice.
  • the method further comprises thermal annealing the light guide optical element.
  • the light guide optical element is characterised by a transparency of more than about 85%.
  • the present disclosure also provides a 3D printed light guide optical element formed by the method as disclosed herein.
  • the present disclosure also provides 3D printed light guide optical element, comprising: a) an ultra-transparent body having a first surface; and b) at least one semitransparent beam splitter within the ultra-transparent body and angled relative to the first surface; wherein the 3D printed light guide optical element is characterised by at least one 3D printed slice having a different refractive index relative to an adjacent 3D printed slice.
  • the present disclosure also provides 3D printed light guide optical element, comprising: a) an ultra-transparent body having a first surface; and b) at least one semitransparent beam splitter within the ultra-transparent body and angled relative to the first surface; wherein a cross section of the 3D printed light guide optical element is characterised by a portion of the cross section having a different refractive index relative to another portion.
  • Figure 1 (Left) 2D Schematics of waveguide showing reflector orientation, image formation direction and direction of light coupling. (Right) 3-Dimensional representation of a waveguide.
  • Figure 2. Ray trace showing light path, image combination and pupil expansion as light propagates from coupling optics to the end user eye.
  • Figure 3 (Left) Object (bitmap file) loaded into model such that the spatial density of rays released from the object surface is proportional to the value of the imported bitmap. (Right) Reconstructed image at the Image plane using 23000 rays showing magnified, perfectly stitched image (rotated for ease of view).
  • Figure 4. 3D printed base of the light guide optical element.
  • FIG. 1 A 3D printed AR waveguide display prototype and see through image displayed. The image was coupled from a LCOS based light engine. A camera was used to capture the floating image.
  • Figure 6 A side view of the light guide optical element with layers of different refractive index to compensate total internal refraction (TIR) imaging shift in case of curved waveguide.
  • TIR total internal refraction
  • Figure 7 Ray trace showing light path, image combination, and pupil expansion as light propagates from coupling optics to the user's eye.
  • the object (bitmap file) is loaded into the model in such a way that the spatial density of rays released from the object surface is proportional to the values in the imported bitmap.
  • the reconstructed image at the image plane generated using 23,000 rays, displays a magnified, perfectly stitched, and flipped image.
  • a 2D schematic of the waveguide illustrates the critical angles and dimensions of the combiner.
  • Figure 8. The adapted printing platform and the fabrication process. Schematics illustrate the modified 3D printing platform. To enhance light distribution uniformity, a diffuser and an absorber were placed in front of the light source. Additionally, another diffuser was positioned on top of the LCD screen. The top and bottom components of the waveguide were printed separately on glass printing beds and later integrated with the dielectric reflectors.
  • FIG. 9 Illumination uniformity and LCD inter-pixel gap issues.
  • Left A comparative example showing the illumination uniformity with and without the use of the light source diffuser. As the intensity of the light source is too strong, saturating the camera sensor, an optical filter is employed to reduce the LED intensity, revealing illumination patterns depicted in the bottom right subfigures.
  • the LCD diffuser Without the LCD diffuser, the printed sample displayed numerous fine lines within the body, as indicated by the arrows. However, these lines disappeared after the diffuser was applied. To enhance line visibility, the transparent sample was placed on a piece of black paper and observed under a microscope.
  • Figure 10 Surface roughness and transmittance ratio of the reflector and the 3D printed sample with a thickness of 3mm.
  • Left The 2D surface roughness maps of the reflector and a printed resin block were measured over a small area (5 pm x 2.5 pm).
  • the transmittance ratio of the reflector was measured at an incident angle of 0-degree and 65-degree.
  • the transmittance ratio of the 3D printed resin block was measured at an incident angle of 0-degree, showing an average transmittance ratio of 92.3% above 420nm.
  • Figure 12. (a) The design of an optical system, (b) The left figure shows the objective bitmap image and the right figure demonstrates the stitched reconstructed image at the retina, (c) An illustration of the fabrication process.
  • Figure 13. (a) A prototype of the liquid optical combiner, (b) An example of the virtual image captured through the liquid optical combiner, which overlaps with the lab environment. The projected source image is shown in the bottom-left corner.
  • AR augmented reality
  • ultra transparent liquid resin may be used in 3D printing technology to additively or synergistically to solve the above mentioned problems, by facilitating the production of 3D-printed optics that exhibit a quality comparable to that of traditional optical components.
  • This specialized resin is formulated to minimize cloudiness and demonstrate low shrinkage after UV light curing, thereby enabling the fabrication of AR. optical combiners that offer exceptional clarity and transparency.
  • Additive manufacturing involves the successive layer-by-layer deposition of material to generate a three- dimensional object. This approach facilitates the production of complex and customized geometries that may pose difficulties when utilizing traditional manufacturing techniques.
  • 3D printing allows for streamlined mass production and decreased production expenses. Accordingly, a 3d printing method suitable for making optical quality AR displays is disclosed herein.
  • the present disclosure relates to a method of 3D printing a light guide optical element, comprising: a) 3D printing a base structure using at least one ultra-transparent liquid resin, the base structure comprising a first surface and at least one holding means formed at a second surface opposite to the first surface and angled relative to the first surface; b) contacting at least one semitransparent beam splitter to the at least one holding means; and c) contacting the at least one ultra-transparent liquid resin over the at least one semitransparent beam splitter and curing the at least one ultra-transparent liquid resin in order to form the light guide optical element.
  • the present disclosure relates to a 3D printing technique to make light guide optical element (LOE) for augmented reality display.
  • LOE light guide optical element
  • the disclosure enables efficient mass production and is particularly useful in near-eye displays.
  • the LOE is designed to manipulate the direction and intensity of the light.
  • 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer control, with material being added together (such as plastics, liquids or powder grains being fused), typically layer by layer.
  • Stereolithography SLA
  • Digital Light Processing DLP
  • SLA Stereolithography
  • DLP Digital Light Processing
  • SLA a laser at the UV frequency is directed towards the vat of liquid resin.
  • the point of emission is controlled by a mirror galvanometer.
  • the laser moves along a single layer of the resin spot by spot until the layer is completed, after which the build platform moves to allow for the fresh resin to be exposed to UV radiation.
  • DLP the process is similar except that UV radiation is projected on an entire layer at a time using an array of micrometer-sized mirrors, each of which can rotate to control the point of emission of UV radiation.
  • a panel of LED lights may also be used.
  • printing can be done at either the bottom- up or top-down orientations. The major difference between the two is the location of the light source.
  • the 3D printing is resin based 3D printing.
  • This is an additive manufacturing method that cure liquid photopolymers layer-by-layer into a solid object.
  • the 3D printing may be stereolithography (SLA) 3D printing.
  • a printing bed or platform may be immersed in a transparent resin vat and exposed to UV light emitted by an array of LEDs from the bottom or from the top.
  • a UV screen may be used to mask UV light so as to be able to print an appropriate 3D structure.
  • the screen may provide a pixel resolution of about 22pm, and the dual linear rails offer a stable z-axis step size of 10 pm.
  • the 3D printing process for the light guide optical element may involve first designing the base structure using computer-aided design (CAD) software, as shown in Figure 4. Other software may be used.
  • CAD computer-aided design
  • Other software may be used.
  • the base structure is thus printed following a template in a slice-by-slice manner.
  • the template may be designed to incorporate at least one holding means.
  • the light guide optical element may be configured for different augmented reality displays.
  • the base structure may be printed using a liquid crystal display (LCD) 3D printer.
  • LCD 3D printer is configured to provide a LCD screen which is generated based on a layer of a model of the 3D structure to be printed. UV light may transmit through the LCD screen which cures the resin. In this way, an entire layer may be irradiated at once with UV light. This means that 3D printing with a 3D LCD printer may be faster and more precise than with other 3D printers.
  • the LCD 3D printer differs from other types of 3D printers, such as DLP or SLA printers, in its light source.
  • LCD 3D printers use a UV LCD array as a light source. As a result, the light from the LCD flat panels shines directly, in a parallel fashion, onto the work area. Since this light is not expanded, pixel distortion is much less of a problem with LCD printing.
  • the at least one ultra-transparent liquid resin may be poured into the 3D printer slowly so as not to generate air bubbles.
  • the base structure is 3D printed on a substrate.
  • the substrate may have a smooth surface, such as glass.
  • the surface of the substrate may be polished or etched with ozone water.
  • the substrate may be temporarily held to the printing bed by an adhesive such as glue or double sided tape.
  • step a) comprises depositing and at least partially curing the at least one ultra-transparent liquid resin in a slice-by-slice manner.
  • step a) comprises varying a refractive index of the at least one ultra-transparent liquid resin such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • step a) comprises varying a curing duration of the ultra- transparent liquid resin such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • step a) comprises at least partially curing (or polymerising) the at least one 3D printed slice of the base structure under different conditions relative to the adjacent 3D printed slice.
  • the at least one 3D printed slice is at least partially cured under a pattern of light which is different relative to the adjacent 3D printed slice. In some embodiments, the at least one 3D printed slice is at least partially cured under a light intensity which is different relative to the adjacent 3D printed slice. The intensity of the light may be adjusted within the range 0-3 W/cm 2 . Thus, for example, one 3D printed slice may be cured using light of about 2.1 W/cm 2 , while an adjacent slice may be cured using light of about 2.2 W/cm 2 .
  • step a) comprises 3D printing the base structure using a second ultra-transparent liquid resin having a different refractive index such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • a 3D printed slice may be formed using the at least one ultra-transparent liquid resin and an adjacent slice may be formed using the second ultra-transparent liquid resin.
  • step a) comprises 3D printing the base structure using a mixture of the at least one ultra-transparent liquid resin and a second ultra- transparent liquid resin having a different refractive index such that at least one 3D printed slice of the base structure has a different refractive index relative to an adjacent 3D printed slice.
  • the refractive index of the resultant 3D slice is varied by a ratio of the at least one ultra-transparent liquid resin and the second ultra-transparent liquid resin. By having 3D slices with different ratios, the refractive index may be varied or gradiented.
  • step a) comprises: i) 3D printing a slice of the base structure; ii) mixing a portion of a second ultra-transparent liquid resin to the at least one ultra-transparent liquid resin; iii) 3D printing a subsequent slice of the base structure; and iv) iteratively repeating step ii) and iii) until the base structure is formed.
  • This method may be performed in a single 3D printer, by sequentially pouring in the second ultra-transparent liquid resin into a resin vat such that the ratio of second ultra-transparent liquid resin to the at least one ultra-transparent liquid resin increases sequentially.
  • multiple 3D printers may be used, each of which comprises a resin vat of different resin ratio.
  • the difference in refractive index between the 3D printed slices is about 0.001 to about 0.1.
  • the difference in refractive index is about 0.002 to about 0.1, about 0.004 to about 0.1, about 0.006 to about 0.1, about 0.008 to about 0.1, about 0.01 to about 0.1, about 0.02 to about 0.1, about 0.04 to about 0.1, 0.06 to about 0.1, or about 0.08 to about 0.1.
  • the ultra-transparent liquid resin is a UV curable resin. In some embodiments, the ultra-transparent liquid resin is an epoxy based resin. In some embodiments, the ultra-transparent liquid resin is an acrylic based resin. The liquid resin may comprise acrylic monomers, methacrylic monomers, or a combination thereof. When exposed to UV radiation, these monomers quickly form molecular bonds with each other and turn into a solid polymer. In some embodiments, the ultra-transparent liquid resin is NOVA3D ultra-clear resin, Stratasys VeroClear resin, their variants or a combination thereof.
  • step a) is performed at an ambient temperature, or preferably at about 20 °C to about 40 °C.
  • the ultra-transparent liquid resin is characterised by a refractive index of about 1.5 to about 2.
  • the refractive index is about 1.5 to about 1.9, about 1.5 to about 1.8, about 1.5 to about 1.7, or about 1.5 to about 1.6.
  • NOVA3D ultra-clear resin may be used, which has a refractive index of about 1.53.
  • the ultra-transparent liquid resin is characterised by a viscosity of about of about 400 MPa to about 700 MPa, or preferably about 450 MPa to about 600 MPa.
  • the ultra-transparent liquid resin is characterised by a volume shrinkage of less than 8%, or preferably less than 1%. In other embodiments, the volume shrinkage is less than 7%, 6%, 5%, 4%, 3% or 2%.
  • NOVA3D ultra-clear resin may be used, which exhibits a volume shrinkage of 3.6% upon curing at 25°C.
  • the method further comprises a step before step a) of processing the ultra-transparent liquid resin. This allows the refractive index to be varied.
  • the 3D printing is further performed in the presence of a release liner.
  • the release liner may form a film on a surface of the ultra- transparent liquid resin when contained in a liquid vat.
  • the release liner may be perfluoroalkoxy alkanes (PFA).
  • the 3D printing is further performed in the presence of a hydrophobic material.
  • the hydrophobic material provides non-stick properties to the 3D printed structure.
  • the hydrophobic material may form a film on top of the release liner.
  • the hydrophobic material may be polytetrafluoroethylene (PTFE).
  • the 3D printing is performed in the presence of a light diffuser.
  • the diffuser spreads out light, and makes bright or harsh light softer across a wider area, eliminating unwanted glare.
  • the diffuser may be positioned in a light path between the light source and the LCD screen. Further, a second diffuser may be positioned in a light path between the LCD screen and the 3D printed structure.
  • the 3D printing is performed in the presence of a light absorber.
  • the light absorber may be positioned parallel and externally to a light path so as to remove stray light from the light source to the LCD screen.
  • the 3D printing is performed using an anti-aliasing function.
  • Antti-aliasing is a computer graphics technique that smoothes jagged edges on curves and diagonal lines. It helps to make digital images appear more realistic by eliminating the "staircase" effect that often appears on curved or angled lines.
  • the base structure comprises a first surface.
  • the first surface may be in contact with the substrate when 3D printed. In use, the first surface is proximal to a user's eye.
  • the first surface acts to transmit light travelling along a light path in the light guide optical element out of the light guide optical element. In this regard, the light path of the light changes as it is reflected by the semitransparent beam splitter and out of the light guide optical element.
  • the base structure comprises at least one holding means.
  • the holding means is formed at a second surface, which is opposite the first surface.
  • Each holding means may be used to contain a semitransparent beam splitter.
  • the holding means may be a slope cut into the second surface of the base structure, or may be a slot. In some embodiments, the holding means is a triangular recess.
  • the at least one holding means is angled at about 20 ° to about 40 ° relative to the first surface, or preferably about 25 °. In other embodiments, the angle is about 20 ° to about 35 °, or about 20 ° to about 30 °.
  • the angles for the holding means may all be the same, or may be graduated sequentially to allow for light path compensation in a curved light guide optical element.
  • the base structure comprises at least two holding means for contacting at least two semitransparent beam splitters.
  • the at least one holding means is 3 holding means. In some embodiments, the at least one holding means is 6 holding means.
  • the method further comprises a step after step a) of cleaning and further curing the base structure of step a).
  • the base structure may be cleaned in an ultrasonic cleaner with isopropyl alcohol. In some embodiments, alcohol is not used.
  • the base structure may be cured using UV light. These actions may be performed separately or performed together as a single step.
  • the base structure is characterised by a refractive index of about 1.5 to about 2.
  • the refractive index is about 1.5 to about 1.9, about 1.5 to about 1.8, about 1.5 to about 1.7, or about 1.5 to about 1.6.
  • NOVA3D ultra-clear resin may be used.
  • the semitransparent beam splitter may be placed on the holding means by using a pick-and-place machine or by a fixture set moulding according to the base structure. In this sense, the semitransparent beam splitter is inserted into the holding means.
  • the semitransparent beam splitter may be adhered to the holding means and base structure.
  • the semitransparent beam splitter may be deposited via a deposition method or vacuum deposition method such as chemical vapour deposition.
  • the semitransparent beam splitter may also be 3D printed.
  • the semitransparent beam splitter may be 3D printed using a different material.
  • metal filament, metal powder, metal wire, or a metal infused resin may be used.
  • Techniques that may be used include Metal Filament Fused Deposition Melting (FDM), Laser Powder Bed Fusion (LPBF), Electron Beam Powder Bed Fusion, aka Electron Beam Melting (EBM), Metal Binder Jetting, Wire Arc Additive Manufacturing (WAAM), Laser Directed Energy Deposition (Laser DED), Electron Beam Directed Energy Deposition (eBeam DED), Micro Metal 3D Printing, Cold Spray, and Molten Direct Energy Deposition.
  • the at least one semitransparent beam splitter is selected from a dielectric reflector, metal reflector or a combination thereof.
  • the at least one semitransparent beam splitter may have a flat morphology, or a curved morphology.
  • the curved morphology may follow a gradient of a light path in order to direct light to a user.
  • the semitransparent beam splitter may be a dielectric reflector.
  • the dielectric reflector may be a mirror composed of a single thin layer or multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickness of the dielectric layers, one can design an optical coating with specified reflectivity at different wavelengths of light. Light which is not reflected is transmitted through the dielectric reflector. The percentage of the reflected light and transmitted light may be controlled by, for example, the thickness and number of the thin layer.
  • the at least one semitransparent beam splitter is characterised by a transparency of at least about 85%, or preferably at least about 90%.
  • the at least one semitransparent beam splitter is characterised by a transmittance of at least about 85%, or preferably at least about 90%.
  • Transmittance is the fraction of incident light which is transmitted. In other words, it's the amount of light that "successfully" passes through the substance and comes out the other side.
  • the at least one semitransparent beam splitter is characterised by a reflection ratio of about 8% to about 20%, or preferably about 10%.
  • the semitransparent beam splitter is characterised by root mean square (RMS) roughness of about 1.1 nm to about 1.8 nm.
  • RMS root mean square
  • the RMS roughness is about 1.1 nm to about 1.7 nm, about 1.1 nm to about 1.6 nm, about 1.1 nm to about 1.5 nm, or about 1.1 nm to about 1.4 nm.
  • the semitransparent beam splitter is characterised by mean roughness of about 1 nm to about 1.5 nm. In other embodiments, the mean roughness is about 1 nm to about 1.4 nm, about 1 nm to about 1.3 nm, about 1 nm to about 1.2 nm, or about 1 nm to about 1.1 nm.
  • the light guide optical element may be formed from the base structure in several ways.
  • the base structure with the semitransparent beam splitter may be contacted with additional ultra-transparent liquid resin such that it covers the semitransparent beam splitter.
  • the ultra-transparent liquid resin may then be cured to fully encapsulate the semitransparent beam splitter.
  • the contacting and curing step may be performed as a single step or in a layer- by-layer manner using a micro-assembly machine.
  • the ultra-transparent liquid resin may be sufficiently added such that it floods the at least one slope.
  • the ultra-transparent liquid resin may be added such that the semitransparent beam splitter is completely immersed.
  • the second surface of the base structure is formed as a flat surface of the light guide optical element. This surface allows light to pass through the light guide optical element, such that a user can see through the light guide optical element to visualise real images.
  • the at least one ultra-transparent liquid resin in step c) is from a different stock solution.
  • the at least one ultra-transparent liquid resin of step c) is not 3D printed on top of the second surface.
  • the at least one ultra-transparent liquid resin may be poured on the second surface.
  • the method further comprises a step after step a) of immersing the 3D printed base structure in a tank comprising ultra- transparent liquid resin.
  • the at least one semitransparent beam splitter may be contacted to the at least one holding means in the tank.
  • the method further comprises immersing the semitransparent beam splitter in the tank comprising ultra-transparent liquid resin.
  • the semitransparent beam splitter may contact the base structure in the tank comprising ultra-transparent liquid resin. This effectively preventing bubble generation during the placement. This also allows the resin to act as an adhesive for the semitransparent beam splitter to the base structure when cured.
  • step c) comprises contacting the at least one ultra- transparent liquid resin with and/or over the second surface and holding means of the base structure and at least one semitransparent beam splitter and curing the at least one ultra-transparent liquid resin. In this way, the at least one semitransparent beam splitter is adhered to the holding means.
  • the method further comprises a step of separately 3D printing a top structure.
  • the top structure comprises a third surface adjacent to a printer platform, and a fourth surface opposite the third surface.
  • the fourth surface may have a complementary morphology relative to second surface of the base structure and the at least one semitransparent beam splitter.
  • the top structure may be 3D printed on a separate substrate.
  • the top structure may then be mated to the second surface of the base structure and the at least one semitransparent beam splitter to form the light guide optical element.
  • the at least one semitransparent beam splitter may be contacted with the holding means of the second surface of the base structure, and the top structure may be contacted to the at least one semitransparent beam splitter and second surface in the tank comprising ultra-transparent liquid resin. This assembly may then be cured to form the light guide optical element. This effectively preventing bubble generation during the placement.
  • step c) comprises contacting a transparent substrate and the at least one ultra-transparent liquid resin over the holding means and second surface of the base structure to form a covered recess, and curing the at least one ultra-transparent liquid resin such that the transparent substrate is adhered to the second surface.
  • the transparent substrate may be a glass substrate.
  • the at least one ultra- transparent liquid resin acts as a glue.
  • the covered recess may then be filled with a transparent liquid to form the light guide optical element.
  • the covered recess is thus void of air.
  • the transparent liquid is characterised by a refractive index of about 1.4 to about 1.8. In other embodiments, the refractive index is about 1.4 to about 1.7, about 1.4 to about 1.6, or about 1.4 to about 1.5.
  • the transparent liquid is silicone oil, mineral oil, polydimethylsiloxane (PDMS), or a combination thereof.
  • step c) further comprises applying a pressure to the at least one semitransparent beam splitter during curing such that it homogenously contacts the holding means and/or the second surface.
  • a pressure may be applied between the base structure and the top structure.
  • a pressure may be applied between the transparent substrate and the base structure.
  • the at least one ultra-transparent liquid resin is cured under inert conditions in the presence of UV radiation.
  • the inert condition may be a stream of nitrogen gas.
  • the at least one ultra-transparent liquid resin may be cured in a nitrogen chamber.
  • step c) comprises 3D printing the ultra- transparent liquid resin over the at least one semitransparent beam splitter.
  • step c) comprises depositing and at least partially curing the ultra-transparent liquid resin in a slice-by-slice manner. In this way, any gap or space adjacent to the at least one semitransparent beam splitter may be filled up in a layer-by-layer manner.
  • step c) comprises varying a refractive index of the ultra- transparent liquid resin such that at least one 3D printed slice has a different refractive index relative to an adjacent 3D printed slice.
  • the method further comprises a step of thermally treating the light guide optical element.
  • the thermal treatment may be subjecting the light guide optical element to about 40°C to about 80°C for about 20 min to about 60 min. This helps to relieve the internal stress of the light guide optical element that accumulated during the curing phase.
  • the temperature is about 40°C to about 70°C, about 40°C to about 60°C, or about 40°C to about 50°C.
  • the duration is about 20 min to about 50 min, about 20 min to about 40 min, or about 20 min to about 30 min.
  • the method further comprises a step of removing the substrate from the light guide optical element.
  • the substrate may be a glass, which may be separated from the light guide optical element using a sharp blade.
  • the base structure further comprises a prism structure at an end thereof.
  • the prism structure facilitates efficient coupling of light into the waveguide.
  • the prism may be 3D printed together with the base structure.
  • the prism may be a triangular prism.
  • the prism may be placed at an angle of about 40° to about 60° relative to the first surface of the base structure and correspondingly the light guide optical element. This angle ensures total internal reflection within the light guide optical element, enabling optimal light transmission along its path. In some embodiments, the angle is 50°.
  • the method further comprises a step after step c) of cleaning the light guide optical element.
  • the method further comprises a step after step c) of further curing the light guide optical element.
  • the method further comprises varying a refractive index of the light guide optical element such that at least one 3D printed slice of the light guide optical element has a different refractive index relative to an adjacent 3D printed slice.
  • the method further comprises thermal annealing the light guide optical element in order to vary a refractive index of the light guide optical element.
  • thermal annealing By controlling the temperature and duration of the annealing process, a gradient in refractive index can be created.
  • the method further comprises rapidly cooling the light guide optical element.
  • the surfaces of the LOE may be polished or laminated with the same material or a different optical material to ensure smoothness and clarity.
  • the method further comprises a step after step c) of polishing the surfaces of the light guide optical element.
  • the light guide optical element is characterised by a transparency of more than about 85%.
  • the light guide optical element is characterised by a transmittance of at least about 85% from 420 nm to 700 nm, or preferably at least about 90%.
  • the light guide optical element is characterised by a length of about 20 mm to about 50 mm. In some embodiments, the light guide optical element is characterised by a length of about 20 mm to about 45 mm, about 20 mm to about 40 mm, about 25 mm to about 40 mm, or about 30 mm to about 40 mm.
  • the light guide optical element is characterised by a width of about 20 mm to about 50 mm. In some embodiments, the light guide optical element is characterised by a width of about 20 mm to about 45 mm, about 20 mm to about 40 mm, about 20 mm to about 35 mm, orabout 20 mm to about 30 mm.
  • the light guide optical element is characterised by a thickness of about 2 mm to about 15 mm. In some embodiments, the light guide optical element is characterised by a thickness of about 2 mm to about 10 mm, or about 2 mm to about 5 mm. In some embodiments, the light guide optical element is characterised by a thickness of about 3 mm or about 7.5 mm.
  • the present disclosure also provides a 3D printed light guide optical element formed by the method as disclosed herein.
  • the portion of the resin which is 3D printed and the portion of the resin which is filled in the recess of the base structure (not 3D printed) may have the same refractive index if the same resin material is used.
  • the present disclosure also provides 3D printed light guide optical element, comprising: a) an ultra-transparent body having a first surface; and b) at least one semitransparent beam splitter within the ultra-transparent body and angled relative to the first surface; wherein the 3D printed light guide optical element is characterised by at least one 3D printed slice having a different refractive index relative to an adjacent 3D printed slice.
  • the present disclosure also provides 3D printed light guide optical element, comprising: a) an ultra-transparent body having a first surface; and b) at least one semitransparent beam splitter within the ultra-transparent body and angled relative to the first surface; wherein a cross section of the 3D printed light guide optical element is characterised by a portion of the cross section having a different refractive index relative to another portion.
  • the 3D printed light guide optical element further comprises a projector.
  • the 3D printed light guide optical element further comprises a lens.
  • the lens may be adjacent to the prism.
  • the lens may have a focal length of about 20 mm to about 50 mm, about 20 mm to about 45 mm, about 20 mm to about 40 mm, about 20 mm to about 35 mm, about 20 mm to about 30 mm, or about 20 mm to about 25 mm.
  • the 3D printed light guide optical element is characterised by a magnification ratio of about 1.1 to about 1.8. In some embodiments, the magnification ratio is about 1.1 to about 1.7, about 1.2 to about 1.7, about 1.3 to about 1.7, or about 1.4 to about 1.7. In some embodiments, the magnification ratio is about 1.4.
  • the 3D printed light guide optical element is characterised by root mean square (RMS) surface roughness of about 1.1 nm to about 1.8 nm.
  • RMS root mean square
  • the RMS roughness is about 1.1 nm to about 1.7 nm, about 1.1 nm to about 1.6 nm, about 1.1 nm to about 1.5 nm, or about 1.1 nm to about 1.4 nm.
  • the 3D printed light guide optical element is characterised by mean surface roughness of about 1 nm to about 1.5 nm.
  • the mean roughness is about 1 nm to about 1.4 nm, about 1 nm to about 1.3 nm, about 1 nm to about 1.2 nm, or about 1 nm to about 1.1 nm.
  • the mean roughness is about 1.1 nm to about 1.5 nm, about 1.2 nm to about 1.5 nm, about 1.3 nm to about 1.5 nm, or about 1.4 nm to about 1.5 nm.
  • the waveguide or LOE is illustrated in Figure 1.
  • Light from a source or light engine may be coupled into the waveguide by a prism and directed towards the user's eye through the use of reflectors.
  • Figure 1 shows a waveguide with three reflectors. A simulation is performed to demonstrate the efficacy of this waveguide as shown in Figure 2.
  • Figure 2 presents the simulated light paths. Due to a combinatory effect of the reflectors and the micro-patterns on the first surface, the resulting image is combined at the retina of the eye.
  • Figure 3 shows an example of the reconstructed image generated by the waveguide of the present disclosure.
  • Figure 5 shows a waveguide prototype and image captured using a camera placed next to the waveguide.
  • the design incorporates three dielectric reflectors, integrated at an angle of 25 degrees relative to the bottom surface, as illustrated in Fig. 1, 2 and 7. These reflectors serve the purpose of directing the light toward the observer's eye.
  • the projector used in our design is a general LCOS projector with a 40° field of view, which emits a virtual image that is subsequently coupled into the waveguide through the triangular prism.
  • the simulation parameters included a refractive index of 1.53 for the resin material used in the waveguide.
  • the dielectric reflectors employed in the waveguide were assigned a transmittance ratio of 90% based on actual measurements, and wall boundary conditions were applied.
  • Fig. 2 and 7 shows the simulated ray tracing results, illustrating the propagation of light rays through the waveguide, their convergence at the retina, and the formation of the final image.
  • An example of the computationally reconstructed University of Melbourne's crest is also shown in the figure.
  • an object bitmap file of the crest
  • the spatial distribution of rays released from the object's surface was proportional to the bitmap's values.
  • This waveguide design not only demonstrates its efficacy in providing high-quality image reconstruction but also takes into consideration its feasibility for fabrication.
  • the optimized geometric AR. waveguide was fabricated using a semi-custom level 3D printer.
  • Our platform is constructed based on the Phrozen Sonic mini 8K resin 3D printer, which is a custom-level liquid-crystal display (LCD) 3D printer. Briefly, a printing bed is immersed in a transparent resin vat and exposed to UV light emitted by an array of LEDs at the bottom. The UV light passes through an LCD screen, acting as a masking element. This reveals the image pattern on the printing bed and selectively cures corresponding pixels. This layering process is repeated for subsequent layers.
  • the LCD screen provides an impressive ultra-high pixel resolution of 22pm, and the dual linear rails offer a stable z-axis step size of 10 pm.
  • a diffuser and an absorber were placed in front of the light source. Additionally, another diffuser was placed on top of the LCD screen to address the issue of LCD inter-pixel gaps and ensure a seamless display of the image pattern (Fig. 8).
  • the second diffuser did not significantly impact the x-y plane resolution, particularly when the z-axis step size was under 20pm. This observation held true, especially for objects lacking intricate details.
  • the resin vat incorporated a thin perfluoroalkoxy (PFA) film as a release liner, aiming for a non-adhesive surface that facilitated the removal of the printed objects upon completion.
  • PFA perfluoroalkoxy
  • a thin layer of polytetrafluoroethylene (PTFE) was coated on the PFA film.
  • PTFE polytetrafluoroethylene
  • N0VA3D ultra-clear resin which had a relatively stable refractive index of around 1.53 in the visible light wavelength range. At 25°C, it exhibited a volume shrinkage of 3.6% upon curing.
  • LCD printers could not offer comparable surface finish roughness.
  • a strategy to mitigate this issue was to print the top and bottom waveguide components separately on glass printing beds, followed by integrating them with dielectric reflectors (as seen in Fig. 8). This approach improved the overall surface finish of the waveguide and potentially enhanced its performance.
  • achieving a smooth finish is not essential since it could be glued to the projector at a later stage.
  • Dielectric reflectors were then carefully placed into the corresponding slots within the resin, effectively preventing bubble generation during the placement. Subsequently, the combined sample was taken out and cured within a nitrogen chamber under UV, with proper pressure applied on the top glass. Then the sample was transferred to a 40°C hot plate and allowed to undergo a 30-minute thermal treatment to relieve the sample's internal stress that accumulated during the curing phase. Finally, the glass slides were removed using a sharp blade.
  • the incorporation of the second diffuser on top of the LCD screen further enhanced the uniformity of illumination, effectively mitigating the LCD inter-pixel gaps issue. Without this diffuser, the printed sample displayed many fine lines within its structure (Fig. 9).
  • the combined printed waveguide has a thickness of 3mm.
  • the planar surface printed on the glass slide exhibits good roughness characteristics. It has an RMS roughness of 1.49 nm and a mean roughness of 1.38 nm (resin block; Fig. 10).
  • the waveguide exhibits low transmittance from 400 nm to 420 nm. However, beyond 420 nm and up to 700 nm, the transmittance ratio consistently remains high, hovering around 90%, which renders it well-suited for a wide range of optical applications within this specific spectral region (Fig. 10).
  • a prototype of the printed AR To validate the efficacy of the design, a prototype of the printed AR.
  • Fig. lla-b the AR waveguide was tested using a commercial microprojector.
  • Fig. llc-d display an example, showing the projected image and the image captured through the waveguide.
  • FIG. 12c shows the fabrication process.
  • the resin we chose was Stratasys VeroClear resin, known for its robust resistance to deformation, showing a flexural strength of at least 75 MPa.
  • support material we opted for a water-soluble support using Stratasys SUP707.
  • the frame was printed using high-guality printing mode, resulting in a z-axis step size of 14pm.
  • the slope of the tri-prism is 50 degrees, and the reflectors are tilted at 25 degrees.
  • the dimensions of the active region of the combiner are 30mm x 26mm x 3.2mm.
  • Figure 12b presents an example of the COMSOL simulation results, demonstrating the reconstructed mushroom image on the retina using the suggested combiner design.
  • Figure 13b demonstrates an example of the virtual image captured through the waveguide that overlaps with the laboratory environment.
  • the total cost of the prototype is around $18. However, the cost can be further reduced during mass production.
  • the sample can be assembled using an automated assembly machine, such as the one from Ficontech. This eliminates the need for dicing, bonding, and polishing required by traditional manufacturing methods.

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Abstract

La présente divulgation concerne des procédés d'impression 3D d'un élément optique de guidage de lumière, comprenant l'impression 3D d'une structure de base à l'aide d'au moins une résine liquide ultratransparente, la structure de base comprenant une première surface et au moins un moyen de support formé au niveau d'une seconde surface en regard de la première surface et incliné par rapport à la première surface ; la mise en contact d'au moins un diviseur de faisceau semi-transparent avec le ou les moyens de support ; la mise en contact de la ou des résines liquides ultratransparentes sur le ou les séparateurs de faisceau semi-transparent et le durcissement de la ou des résines liquides ultratransparentes afin de former l'élément optique de guidage de lumière. La divulgation concerne également les éléments optiques de guidage de lumière à partir de ceux-ci.
PCT/AU2024/050464 2023-05-10 2024-05-10 Procédés d'impression 3d et guides de lumière fabriqués à partir de ceux-ci Pending WO2024229533A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050013578A1 (en) * 2001-08-13 2005-01-20 Toyoda Gosei Co., Ltd. Optical waveguide device manufacturing jig, method of manufacturing optical waveguide device by use of the same jig, and the same optical waveguide device
US20150078712A1 (en) * 2013-09-17 2015-03-19 Telefonaktiebolaget L M Ericsson (Publ) Method, Apparatus and Optical Interconnect Manufactured by 3D Printing
US20170299810A1 (en) * 2014-09-25 2017-10-19 Anteryon Wafer Optics B.V. An optical light guide element and a method for manufacturing
US20170348903A1 (en) * 2015-02-10 2017-12-07 Optomec, Inc. Fabrication of Three-Dimensional Materials Gradient Structures by In-Flight Curing of Aerosols
US20210088728A1 (en) * 2018-02-23 2021-03-25 Commscope Technologies Llc 3d printed fiber optic connector end face and method of manufacture
US20230023734A1 (en) * 2019-12-09 2023-01-26 Jarvish Pty Ltd. Light guiding apparatus and guiding method thereof

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050013578A1 (en) * 2001-08-13 2005-01-20 Toyoda Gosei Co., Ltd. Optical waveguide device manufacturing jig, method of manufacturing optical waveguide device by use of the same jig, and the same optical waveguide device
US20150078712A1 (en) * 2013-09-17 2015-03-19 Telefonaktiebolaget L M Ericsson (Publ) Method, Apparatus and Optical Interconnect Manufactured by 3D Printing
US20170299810A1 (en) * 2014-09-25 2017-10-19 Anteryon Wafer Optics B.V. An optical light guide element and a method for manufacturing
US20170348903A1 (en) * 2015-02-10 2017-12-07 Optomec, Inc. Fabrication of Three-Dimensional Materials Gradient Structures by In-Flight Curing of Aerosols
US20210088728A1 (en) * 2018-02-23 2021-03-25 Commscope Technologies Llc 3d printed fiber optic connector end face and method of manufacture
US20230023734A1 (en) * 2019-12-09 2023-01-26 Jarvish Pty Ltd. Light guiding apparatus and guiding method thereof

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