Systems, devices, and methods for beam combining in wearable heads-up displays

• US 10,365,492 B2
• Filed: 12/20/2017
• Issued: 07/30/2019
• Est. Priority Date: 12/23/2016
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: North Inc.
• Inventors: Holland, Lloyd Frederick, Moore, Joshua
• Primary Examiner(s): Font, Frank G
• Application Number:
  US15/848,388
• Publication Number:
  US 20180180886A1
• Time in Patent Office: 587 Days
• Field of Search: 359632, 359633, 359634, 359636, 353 31, 353 81, 353 84
• CPC Class Codes: G02B 2027/0114 comprising dichroic elements
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/108 for sampling a portion of a beam or combining a small beam in a larger one, e.g. wherein the area ratio or power ratio of the divided beams significantly differs from unity, without spectral selectivity
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

Systems, devices, and methods for beam combining are described. A monolithic beam combiner includes a solid volume of optically transparent material having two orthogonally positioned planar input surfaces, an output surface, and at least two planar dichroic reflectors positioned within the solid volume. Multiple light sources input light into the solid volume through the two planar input surfaces such that each light beam from a respective source is initially incident on one of the planar dichroic reflectors. The light is reflected by and transmitted through the reflectors and an aggregate beam is created. Because the reflectors are within an optically transparent material the beam combiner can be made more compact than a conventional beam combiner. This monolithic beam combiner is particularly well suited for use laser projectors and in wearable heads-up displays that employ laser projectors.

Claims

1. A wearable heads-up display (WHUD) comprising:

a transparent combiner;

a support structure that in use is worn on the head of a user, and which positions the transparent combiner within a field of view of the user when the support structure is worn on the head of the user;

a laser projector carried by the support structure, the laser projector comprising;

a first laser diode operable to output laser light in a first waveband;

a second laser diode operable to output laser light in a second waveband, wherein the first waveband is different from the second waveband and the first waveband and second waveband do not overlap;

at least a third laser diode operable to output laser light in a third waveband, wherein the third waveband is different from the first waveband and the second waveband and the first waveband, second waveband, and third waveband do not overlap;

at least one controllable reflector operable to scan the laser light over the transparent combiner in a field of view of the eye of a user; and

a monolithic beam combiner comprising;

a solid volume of optically transparent material that includes a first planar input surface, a second planar input surface, and a first output surface, wherein the first planar input surface is oriented and positioned opposite the first output surface across a length of the monolithic beam combiner and the second input surface is positioned and oriented orthogonal to the first input surface, and wherein the first laser diode is positioned and oriented to direct laser light in the first waveband at the first planar input surface at an at least approximately 90°

angle, the second laser diode is positioned and oriented to direct laser light in the second waveband at the second planar input surface at an at least approximately 90°

angle, and the third laser diode is positioned and oriented to direct laser light in the third waveband at the second planar input surface at an approximately 90°

angle;

a first planar dichroic reflector within the solid volume, the first planar dichroic reflector transmissive of light in the first waveband and reflective of light in the second waveband and oriented at an at least approximately 45°

angle relative to the first planar input surface and the second planar input surface; and

at least a second planar dichroic reflector within the solid volume, the second planar dichroic reflector transmissive of light in the first waveband and light in the second waveband, reflective of light in the third waveband, and oriented parallel to the first planar dichroic reflector at an at least approximately 45°

angle relative to the first planar input surface and the second planar input surface;

wherein;

the first dichroic planar reflector is positioned to receive laser light in the first waveband from the first laser diode and transmit the laser light in the first waveband through the at least a second planar dichroic reflector towards the first output surface;

the first planar dichroic reflector is positioned to receive laser light in the second waveband from the second laser diode and reflect the laser light in the second waveband through the at least a second planar dichroic reflector towards the first output surface;

the second planar dichroic reflector is positioned to receive laser light in the third waveband from the third laser diode and reflect the laser light in the third waveband towards the first output surface; and

the first output surface is oriented to output an aggregate laser beam comprising laser light in the first waveband, the second waveband, and at least laser light in the third waveband.

2. The WHUD of claim 1 wherein the first output surface of the solid volume is a planar first output surface that is parallel to the first planar input surface and orthogonal to the second planar input surface, and wherein:

the first planar dichroic reflector is oriented at an at least approximately 45°

angle relative to the planar first output surface;

the second planar dichroic reflector is oriented at an at least approximately 45°

angle relative to the planar first output surface;

the first planar dichroic reflector is positioned to receive laser light in the first waveband from the first laser diode and transmit the laser light in the first waveband towards the second planar dichroic reflector at an at least approximately 90°

angle relative to the planar first output surface;

the second planar dichroic reflector is positioned to receive laser light in the first waveband from the planar reflector and transmit the laser light in the first waveband towards the planar first output surface at an at least approximately 90°

angle relative to the planar first output surface;

the first planar dichroic reflector is positioned to receive laser light in the second waveband from the second laser diode and reflect the laser light in the second waveband towards the second planar dichroic reflector at an at least approximately 90°

angle relative to the planar first output surface;

the second planar dichroic reflector is positioned to receive laser light in the second waveband from the planar reflector and transmit the laser light in the second waveband towards the planar first output surface at an at least approximately 90°

angle relative to the planar first output surface; and

the second planar dichroic reflector is positioned to receive laser light in the third waveband from the third laser diode and transmit the laser light in the third waveband towards the planar first output surface at an at least approximately 90°

angle relative to the planar first output surface.

3. The WHUD of claim 1 wherein the shape of the volume is a parallelepiped.

4. The WHUD of claim 1 further comprising:

a fourth laser diode operable to output light in a fourth waveband, wherein the fourth waveband is discrete from the first waveband, the second waveband, and the third waveband; and

a third planar dichroic reflector;

wherein

the third planar dichroic reflector is transmissive of light in the first waveband, transmissive of light in the second waveband, transmissive of light in the third waveband and reflective of light in the fourth waveband and oriented parallel to first planar dichroic reflector and at an at least approximately 45°

angle relative to the first planar input surface and the second planar input surface; and

wherein

the third planar dichroic reflector is positioned to receive laser light in the first waveband, laser light in the second waveband, and laser light in the third waveband from the second planar dichroic reflector and transmit laser light in the first waveband, laser light in the second waveband, and laser light in the third waveband towards the first output surface;

the third planar dichroic reflector is positioned to receive laser light in the fourth waveband from the fourth laser diode and transmit the laser light in the fourth waveband towards the first output surface;

the first output surface is oriented to output an aggregate laser beam comprising laser light in the first waveband, the second waveband, the third waveband, and the fourth waveband.

5. The WHUD of claim 4 wherein the first laser diode is a red laser diode that outputs red laser light and the first waveband comprises red wavelengths, the second laser diode is a green laser diode that outputs green laser light and the second waveband comprises green wavelengths, the third laser diode is a blue laser diode that outputs blue laser light and the third waveband comprises blue wavelengths, and the fourth laser diode is an infrared laser diode that outputs infrared laser light and the fourth waveband comprises infrared wavelengths, and wherein the first planar dichroic reflector transmits red laser light and reflects green laser light, the second planar dichroic reflector transmits red laser light and green laser light and reflects blue laser light, and the third planar dichroic reflector transmits red laser light, green laser light, and blue laser light and reflects infrared laser light.

6. The WHUD of claim 1 wherein the first output surface of the monolithic combiner includes an aperture through which the aggregate beam passes, wherein the aperture shapes the aggregate beam.

7. The WHUD of claim 6 wherein the aperture shapes the aggregate beam to at least approximately match an area and shape of a reflective surface of the controllable reflector.

8. The WHUD of claim 6 wherein the aperture is elliptical.

9. The WHUD of claim 6 wherein the first output surface of the monolithic combiner is etched to create the aperture.

10. The WHUD of claim 6 wherein the first output surface of the monolithic combiner is printed to create the aperture.

11. The WHUD of claim 1 wherein the WHUD further includes a plate with an aperture, the plate carried by the monolithic combiner and positioned to orient the aperture at the first output surface such that the aperture shapes the aggregate beam.

12. The WHUD of claim 11 wherein the aperture shapes the aggregate beam to at least approximately match an area and shape of a reflective surface of the controllable reflector.

13. The WHUD of claim 11 wherein the aperture is elliptical.

14. The WHUD of claim 1 wherein the WHUD further comprises:

at least a first photodiode; and

the monolithic combiner further includes;

a second output surface, positioned opposite the first input surface;

at least a first beam splitter, the first beam splitter positioned between the at least a first planar dichroic reflector and the first output surface and oriented parallel to the planar reflector and the first planar dichroic reflector; and

wherein

the first beam splitter transmits a first portion of the aggregate laser beam towards the first output surface and reflects a second portion of the aggregate laser beam through the second output surface towards the first photodiode.