Systems, devices, and methods for beam combining in laser projectors

• US 10,437,074 B2
• Filed: 12/22/2017
• Issued: 10/08/2019
• Est. Priority Date: 01/25/2017
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: North Inc.
• Inventors: Holland, Lloyd Frederick, Moore, Joshua
• Primary Examiner(s): Alexander, William R
• Assistant Examiner(s): Parbadia, Balram T
• Application Number:
  US15/852,282
• Publication Number:
  US 20180210213A1
• Time in Patent Office: 655 Days
• CPC Class Codes: G02B 2027/0114 comprising dichroic elements
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/104 for use with scanning systems scanning systems G02B26/10
• 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: 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
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607

Abstract

Systems, devices, and methods for beam combining within laser projectors are described. A laser projector includes first, second, and third laser diodes to generate red, green, and blue laser light respectively, a controllable scan mirror, and a heterogeneous beam splitter system. The red, green, and blue laser light have distinct maximum powers. The heterogeneous beam splitter system splits at least one of the red, green, and blue laser light and combines respective first portions of all three into an aggregate beam. Second portions of laser light are excluded from the aggregate beam. At the maximum power of each laser light the aggregate beam is white as defined by a target white point. The heterogeneous beam splitter system directs the aggregate beam towards the controllable scan mirror which scans the beam onto a projection surface. Decreasing the power of the laser light post-generation provides a larger range of aggregate beam colors.

Claims

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

a support structure that in use is worn on the head of user;

a transparent combiner that positions 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 laser module comprising;

a first laser diode to generate laser light in a first waveband having up to a first power P₁;

a second laser diode to generate laser light in a second waveband having up to a second power P₂; and

a third laser diode to generate laser light in a third waveband having up to a third power P₃, wherein the first waveband, the second waveband, and the third waveband are all distinct from one another with no overlap therebetween, and wherein the first power P₁, the second power P₂, and the third power P₃ are all distinct from one another to provide an input power ratio P₁;

P₂;

P₃ that does not correspond to a white point color;

at least one controllable scan mirror; and

a heterogeneous beam splitter system positioned in between the laser module and the at least one controllable scan mirror, the heterogeneous beam splitter system comprising a plurality of beam splitters to combine respective first portions of the laser light in the first waveband, the laser light in the second waveband, and the laser light in the third waveband together into an aggregate beam having up to a fourth power and to exclude respective second portions of at least one of the laser light in the first waveband, the laser light in the second waveband, and the laser light in the third waveband from the aggregate beam to provide the aggregate beam with an output power ratio P₁′

;

P₂′

;

P₃′

that does correspond to a white point color when the fourth power of the aggregate beam is at a maximum value.

2. The WHUD of claim 1, further comprising at least one light absorption surface, wherein the beam splitters of the heterogeneous beam splitter system are positioned and oriented to:

direct the aggregate beam towards the at least one controllable scan mirror; and

route a second portion of the laser light in the first waveband and a second portion of the laser light in the second waveband both towards the at least one light absorption surface.

3. The WHUD of claim 2 wherein at least a subset of the beam splitters of the heterogeneous beam splitter system are positioned and oriented to route a second portion of the laser light in the third waveband towards the at least one light absorption surface.

4. The WHUD of claim 1, further comprising a plurality of photodiodes, wherein the beam splitters of the heterogeneous beam splitter system are positioned and oriented to:

route a second portion of the laser light in the first waveband towards a first photodiode; and

route a second portion of the laser light in the second waveband towards a second photodiode.

5. The WHUD of claim 4 wherein at least a subset of the beam splitters of the heterogeneous beam splitter system are positioned and oriented to route a second portion of the laser light in the third waveband towards a third photodiode.

6. The WHUD of claim 1 wherein the plurality of beam splitters includes a plurality of dichroic reflective elements.

7. The WHUD of claim 6 wherein each dichroic reflective element in the plurality of dichroic reflective elements is oriented parallel to the other dichroic reflective elements in the plurality of dichroic reflective elements at an at least approximately 45°

angle relative to an optical path of the aggregate beam.

8. The WHUD of claim 1 wherein the first laser diode is a red laser diode to generate red laser light, the second laser diode is a green laser diode to generate green laser light, and the third laser diode is a blue laser diode to generate blue laser light.