Systems, devices, and methods for splitter optics in wearable heads-up displays

Patent metadata

Field	Value
Publication number	US-9958682-B1
Application number	US-201615147638-A
Country	US
Kind code	B1
Filing date	May 5, 2016
Priority date	Feb 17, 2015
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

Systems, devices, and methods for optical splitters are described. An optical splitter includes a transparent polygonal structure having an input side to receive light from a light source and an output side that is segmented into multiple facets. Each facet is engineered to provide a respective planar surface that is oriented at a different angle in each of at least two spatial dimensions relative to the other facets in order to refract and route a respective portion of the light along a respective set of optical paths. The input side may be faceted as well to further refine the optical paths. A particular application of the polygonal structure in an optical splitter providing eyebox expansion by exit pupil replication in a scanning laser-based wearable heads-up display is described in detail.

First claim

The invention claimed is:

1. A wearable heads-up display (“WHUD”) comprising:
a support structure that in use is worn on a head of a user;
a scanning laser projector carried by the support structure;
a holographic combiner carried by the support structure, wherein the holographic combiner is positioned within a field of view of an eye of the user when the support structure is worn on the head of the user; and
an optical splitter carried by the support structure and positioned in an optical path between the scanning laser projector and the holographic combiner, wherein the optical splitter includes a transparent polygonal structure that comprises:
an input side oriented to receive laser light from the scanning laser projector and in-couple the laser light into a volume of the optical splitter; and
an output side having N=4 facets, each of the N=4 facets oriented to out-couple a respective portion of the laser light from the volume of the optical splitter and direct the respective portion of the laser light along a respective optical path towards the holographic combiner, wherein:
the N=4 facets are arranged in a two-by-two array with each one of the N=4 facets sharing a first edge with a first other one of the N=4 facets and a second edge with a second other one of the N=4 facets,
each one of the N=4 facets comprises a respective rectangular surface oriented at a different angle in three-dimensional space relative to the other ones of the N=4 facets,
each one of the N=4 facets is oriented to at least partially face away from each of the other ones of the N=4 facets, and
a respective first vertex of each one of the N=4 facets mates with the respective first vertices of each of the other ones of the N=4 facets to form a vertex on a convex outer surface of the output side of the optical splitter, and wherein:
the holographic combiner comprises at least one hologram positioned and oriented to receive the respective portions of the laser light from the N=4 facets of the optical splitter and redirect each respective portion of the laser light towards a respective one of N exit pupils at the eye of the user.

2. The WHUD of claim 1 wherein each of the N=4 facets of the output side of the optical splitter is oriented to direct a respective portion of the laser light from the scanning laser projector along a respective optical path towards the holographic combiner effectively from a different respective one of N spatially-separated virtual positions for the scanning laser projector.

3. The WHUD of claim 1 wherein each of the N=4 facets of the output side of the optical splitter comprises a respective planar surface, and wherein the planar surface of each one of the N=4 facets of the output side of the optical splitter is oriented at a different angle in each of at least two spatial dimensions relative to the other ones of the N=4 facets of the output side of the optical splitter.

4. The WHUD of claim 3 wherein the planar surface of each one of the N=4 facets of the output side of the optical splitter is oriented in a respective plane that intersects each of the respective planes of the other ones of the N=4 facets along a respective line of intersection, and wherein no line of intersection between the respective planes of any pair of facets among the N=4 facets is parallel to any other line of intersection between the respective planes of any other pair of facets among the N=4 facets.

5. The WHUD of claim 1 wherein the input side of the optical splitter includes at least M facets, where M is an integer greater than 1, each of the M facets oriented to in-couple a respective portion of the laser light from scanning laser projector into the volume of the optical splitter and direct the respective portion of the laser light towards a respective subset of P of the N=4 facets on the output side of the optical splitter, where P is an integer less than or equal to N.

6. The WHUD of claim 5 wherein the number N=4 of facets on the output side of the optical splitter is greater than the number M of facets on the input side of the optical splitter and P is less than N.

7. The WHUD of claim 5 wherein the input side of the optical splitter includes M=2 facets, and wherein a first edge of a first one of the M=2 facets mates with a first edge of a second one of the M=2 facets and the first facet and the second facet are oriented to at least partially face one another and form an obtuse angle on a concave outer surface of the input side of the optical splitter.

8. The WHUD of claim 5 wherein each of the M facets of the input side of the optical splitter comprises a respective planar surface, and wherein the planar surface of each one of the M facets of the input side of the optical splitter is oriented at a different angle in at least one spatial dimension relative to the other ones of the M facets of the input side of the optical splitter and relative to each of the N=4 facets of the output side of the optical splitter.

9. The WHUD of claim 1 wherein the optical splitter comprises multiple separate pieces that are bonded together.

10. An optical splitter including a transparent polygonal structure that comprises:
an input side oriented to receive light from a light source and in-couple the light into a volume of the optical splitter; and
an output side having N=4 facets, each of the N=4 facets oriented to out-couple a respective portion of the light from the volume of the optical splitter and direct the respective portion of the light away from the optical splitter along a different respective optical path, wherein the N=4 facets are arranged in a two-by-two array with:
each one of the N=4 facets sharing a first edge with a first other one of the N=4 facets and a second edge with a second other one of the N=4 facets, and
a respective first vertex of each one of the N=4 facets mating with the respective first vertices of each of the other ones of the N=4 facets to form a vertex on a convex outer surface of the output side, and wherein each of the N=4 facets comprises a respective rectangular planar surface that is oriented:
at a different angle in three-dimensional space relative to the respective rectangular planar surfaces of the other ones of the N=4 facets;
to at least partially face away from each of the other ones of the N=4 facets; and
in a respective plane that intersects each of the respective planes of the other ones of the N=4 facets along a respective line of intersection, wherein no line of intersection between the respective planes of any pair of facets among the N=4 facets is parallel to any other line of intersection between the respective planes of any other pair of facets among the N=4 facets.

11. The optical splitter of claim 10 wherein the input side includes at least M facets, where M is an integer greater than 1, each of the M facets oriented to in-couple a respective portion of the light from the light source into the volume of the optical splitter and direct the respective portion of the light towards a respective subset of P of the N=4 facets on the output side, where P is an integer less than or equal to N.

12. The optical splitter of claim 11 wherein the number N=4 of facets on the output side is greater than the number M of facets on the input side and P is less than N.

13. The optical splitter of claim 11 wherein the input side includes M=2 facets, and wherein a first edge of a first one of the M=2 facets mates with a first edge of a second one of the M=2 facets and the first one of the M facets and the second one of the M facets are oriented to at least partially face one another and form an obtuse angle on a concave outer surface of the

Assignees

• Thalmic Labs Inc

Inventors

• Moore Joshua
• Holland Lloyd Frederick

Classifications

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B27/12

  operating by refraction only · CPC title

• G02B2027/0125

  Field-of-view increase by wavefront division · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title