TRANSFLECTIVE HOLOGRAPHIC FILM FOR HEAD WORN DISPLAY

• US 20150362734A1
• Filed: 01/23/2014
• Published: 12/17/2015
• Est. Priority Date: 01/28/2013
• Status: Abandoned Application

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Ecole polytechnique fãdãrale de lausanne epfl (Schweizerische Eidgenossenschaft)
• Inventors: MOSER, Christophe, BRUGGER, Juergen, CADARSO, Victor, GROSSENBACHER, Jonas, GUILLAUME, Mickael, TREMBLAY, Eric
• Application Number:
  US14/763,703
• Publication Number:
  US 20150362734A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 3/0006 Arrays G02B3/02, G02B5/188 take precedence
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02C 7/044 Annular configuration, e.g. pupil tuned
• CPC Class Codes: G03H 1/0248 Volume holograms
• CPC Class Codes: G03H 1/0252 Laminate comprising a hologram layer
• CPC Class Codes: G03H 1/0402 Recording geometries or arrangements G03H1/0443, G03H1/0476, G03H1/16 take precedence
• CPC Class Codes: G03H 1/041 Optical element in the object space affecting the object beam, not otherwise provided for
• CPC Class Codes: G03H 1/0465 Particular recording light; Beam shape or geometry G03H1/06 takes precedence
• CPC Class Codes: G03H 1/181 Pre-exposure processing, e.g. hypersensitisation
• CPC Class Codes: G03H 2001/0264 Organic recording material
• CPC Class Codes: G03H 2001/0415 for recording reflection holograms
• CPC Class Codes: G03H 2001/043 Non planar recording surface, e.g. curved surface
• CPC Class Codes: G03H 2001/0439 for recording Holographic Optical Element [HOE] HOE per se G02B5/32
• CPC Class Codes: G03H 2222/18 RGB trichrome light
• CPC Class Codes: G03H 2223/19 Microoptic array, e.g. lens array
• CPC Class Codes: G03H 2270/21 Curved bearing surface

Abstract

A display panel assembly comprises a transflective holographic screen, i.e., a transparent screen that reflects light from a projection system, comprising at least a volume hologram, a first protective element and a second protective element, each arranged in contact with the volume hologram such that the volume hologram is sandwiched between the first protective element and the second protective element. The display panel assembly further comprises a projection system focusing an image on the volume hologram comprising at least projection optics, mounting means arranged to fixedly mount the projection system relatively to the transflective holographic screen. The volume hologram comprises a plurality of diffractive patterns disposed in sequence across the volume hologram, each of the plurality of diffractive patterns being configured to diffuse the light rays from the projection system in a determined direction corresponding to the specific diffractive pattern and oriented towards a position of an intended eye of a user wearing the display panel assembly.

Claims

1. A display panel assembly comprising

a transflective holographic screen, i.e., a transparent screen that reflects light

from a projection system, comprising at least

a volume hologram,

a first protective element and a second protective element each arranged in contact with the volume hologram such that the volume hologram is sandwiched between the first protective element and the second protective element,

a projection system focusing an image on the volume hologram comprising at least projection optics,

mounting means arranged to fixedly mount the projection system relatively to the transflective holographic screen,

the volume hologram comprising a plurality of diffractive patterns disposed in sequence across the volume hologram, each of the plurality of diffractive patterns being configured to diffuse the light rays from the projection system in a determined direction corresponding to the specific diffractive pattern and oriented towards a position of an intended eye of a user wearing the display panel assembly.

2. The display panel assembly of claim 1, wherein the display panel assembly is used as a Head-Up Display (HUD).

3. The display panel assembly of claim 1, wherein the display panel assembly is further arranged to be used as a near to the eye Head-Worn Display (HWD).

4. The display panel assembly of claim 1, further comprising

a bi-focal contact lens comprising

a centre part which is arranged relative to the transflective holographic screen to collimate the light diffracted by the volume hologram prior entering the intended eye of the user thereby enabling the intended eye of the user to focus onto the transflective holographic screen, and

an outerpart, which surrounds the centre part and is intended to allow an image of a view through the transflective holographic screen to be seen.

5. The display panel assembly of claim 1, wherein the projection system is a scanner projection system that is used to display information on the transflective holographic screen.

6. A method for fabricating the volume hologram of the display panel assembly of claim 1, the method comprising

interfering a reference beam and an object light beam on the photosensitive holographic material, the light beams having similar wavelengths than the light used within the projection system of the display panel, by means of a recording holographic setup, comprising

directing the reference beam to impinge on the photosensitive holographic material with the properties of the projection system, i.e., whereby the properties are indicative at which angle of incidence and with which numerical aperture the reference beam is projected on the photosensitive holographic material,

directing the object beam to impinge on an opposite side of the photosensitive holographic material as compared to the reference beam thereby producing a reflection hologram.

7. The method of claim 6 further comprising

providing the photosensitive holographic material as a film laminated onto a transparent substrate.

8. The method of claim 6 further comprising

providing the photosensitive holographic material as a liquid photopolymer by coating any surface shape in contact with the photosensitive holographic material.

9. The method of claim 8 further comprising

shaping the any surface in contact with the photosensitive holographic material according to one of the following list of shapes:

flat, cylindrical, spherical.

10. The method of claim 6, further comprising

recording the volume hologram either simultaneously or sequentially with several wavelengths to produce a colour screen.

11. The method of claim 6, further comprising

transmitting the object beam through a structure that diffuses light within a given angular spread so that upon use, the then obtained volume hologram enabling the transflective holographic screen to direct the projected light toward the intended eye of the user within a certain angular spread.

12. The method of claim 11 further comprising

providing for the structure that diffuses light a microlens array (MLA) whose lenses'"'"' numerical aperture defines an angular spread of each pixel and a pitch of the microlens array defines a minimum pixel size of the screen.

13. The method of claim 12, wherein a fill factor of the microlens arrays (MLA) is larger than 90%.

14. The method of claim 12, further comprising

replicating the microlens array (MLA) on a curved surface with at least the following fabrication steps:

replicating a negative replica of the microlens array (MLA) in, but not limited to, an elastomer,

dispensing a drop of, but not limited to, curable polymer on a concave side of the curved surface,

whereby the microlens array (MLA) negative replica acts as a mold and a flexibility of the elastomer enables the negative replica to conform to the curved surface,

curing the polymer with a UV curing treatment,

removing the mold to release the microlens array (MLA) on a curved surface.

15. The method of claim 12, further comprising using a condenser lens in combination to the structure that diffuses light such that light is directed toward the intended eye of the user, thus increasing the field of view and tolerance to rotation of the eye.