Hybrid illumination system having a blue laser diode, dichroic mirror and yellow transmissive phosphor converter for generating white light

• US 9,869,442 B2
• Filed: 06/26/2015
• Issued: 01/16/2018
• Est. Priority Date: 06/26/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Bhakta, Vikrant R.
• Primary Examiner(s): MAY, ROBERT J
• Application Number:
  US14/752,738
• Publication Number:
  US 20150377430A1
• Time in Patent Office: 935 Days
• CPC Class Codes: F21S 41/148 the main emission direction of the LED being perpendicular to the optical axis
• CPC Class Codes: F21S 41/16 Laser light sources
• CPC Class Codes: F21S 41/173 Fluorescent light sources
• CPC Class Codes: F21S 41/176 Light sources where the light is generated by photoluminescent material spaced from a primary light generating element
• CPC Class Codes: F21S 41/255 Lenses with a front view of circular or truncated circular outline
• CPC Class Codes: F21S 41/265 Composite lenses; Lenses with a patch-like shape
• CPC Class Codes: F21S 41/30 characterised by reflectors
• CPC Class Codes: F21S 41/33 Multi-surface reflectors, e.g. reflectors with facets or reflectors with portions of different curvature
• CPC Class Codes: F21S 41/645 by electro-optic means, e.g. liquid crystal or electrochromic devices
• CPC Class Codes: F21S 41/675 by moving reflectors
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197
• CPC Class Codes: H01S 5/0071 for beam steering, e.g. using a mirror outside the cavity to change the beam direction
• CPC Class Codes: H01S 5/0087 for illuminating phosphorescent or fluorescent materials, e.g. using optical arrangements specifically adapted for guiding or shaping laser beams illuminating these materials
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

An illumination apparatus is provided that includes a yellow phosphor converter to receive a blue laser light beam and to convert a portion of the blue laser light beam to yellow light, a dichroic mirror optically coupled to the yellow phosphor converter to receive the phosphor-emitted light beam and to filter the phosphor-emitted light beam to provide a dichroic-filtered light beam, the dichroic mirror configured to pass yellow light and to reflect at least some blue light, and a blue light source optically coupled to the dichroic mirror to provide a blue light beam, the dichroic mirror configured to reflect the blue light beam in a same direction as the dichroic-filtered light beam.

Claims

1. An illumination apparatus comprising:

a first blue light source to provide a first blue light beam, wherein the first blue light source is a blue laser light source, and the first blue light beam is a blue laser light beam;

a collimating lens, optically coupled to the first blue light source, to collimate the first blue light beam into a collimated blue light beam;

an optical diffuser, optically coupled to the collimating lens, to optically homogenize the collimated blue light beam into a top hat spatially distributed beam;

a transmissive yellow phosphor converter to convert the top hat spatially distributed beam into a phosphor-emitted light beam having a same direction as the top hat spatially distributed beam, wherein most of the phosphor-emitted light beam is yellow light converted from blue light of the top hat spatially distributed beam;

condensing and collimating lenses, optically coupled to the yellow phosphor converter, to condense and collimate the phosphor-emitted light beam into a condensed and collimated phosphor-emitted light beam;

a dichroic mirror, optically coupled to the condensing and collimating lenses, to filter the condensed and collimated phosphor-emitted light beam into a dichroic-filtered light beam passed by the dichroic mirror, the dichroic mirror configured to pass yellow light and to reflect at least some blue light; and

a second blue light source optically coupled to the dichroic mirror, to provide a second blue light beam, the dichroic mirror configured to reflect the second blue light beam in a same direction as the dichroic-filtered light beam to generate a white light beam.

2. The illumination apparatus of claim 1, in which the yellow phosphor converter is one selected from a group consisting of a transmissive yellow phosphor plate and a transmissive yellow phosphor wheel.

3. The illumination apparatus of claim 1, in which the second blue light source includes a blue light emitting diode.

4. The illumination apparatus of claim 1, in which a portion of the phosphor-emitted light beam is unconverted blue laser light.

5. The illumination apparatus of claim 1, in which the dichroic mirror is configured to reflect all blue light.

6. The illumination apparatus of claim 1, in which the illumination apparatus is included in a headlamp.

7. A headlamp, comprising:

a first blue light source to provide a first blue light beam, wherein the first blue light source is a blue laser light source, and the first blue light beam is a blue laser light beam;

a collimating lens, optically coupled to the first blue light source, to collimate the first blue light beam into a collimated blue light beam;

an optical diffuser, optically coupled to the collimating lens, to optically homogenize the collimated blue light beam into a top hat spatially distributed beam;

a transmissive yellow phosphor converter to convert the top hat spatially distributed beam into a phosphor-emitted light beam having a same direction as the top hat spatially distributed beam, wherein most of the phosphor-emitted light beam is yellow light converted from blue light of the top hat spatially distributed beam;

condensing and collimating lenses, optically coupled to the yellow phosphor converter, to condense and collimate the phosphor-emitted light beam into a condensed and collimated phosphor-emitted light beam;

a dichroic mirror, optically coupled to the condensing and collimating lenses, to filter the condensed and collimated phosphor-emitted light beam into a dichroic-filtered light beam passed by the dichroic mirror, the dichroic mirror configured to pass yellow light and to reflect at least some blue light; and

a second blue light source, optically coupled to the dichroic mirror, to provide a second blue light beam, the dichroic mirror configured to reflect the second blue light beam in a same direction as the dichroic-filtered light beam to generate a white light beam;

a spatial light modulator to modulate the white light beam at a pixel level to generate an image;

illumination optics, optically coupled to the dichroic mirror, to receive and arrange the white light beam to illuminate the spatial light modulator; and

projection optics, optically coupled to the spatial light modulator to receive the image, map pixels of the image to pixels of a larger image, and project the larger image at a distance away from the headlamp.

8. The headlamp of claim 7, in which the spatial light modulator is a digital micromirror device.

9. The headlamp of claim 7, in which the yellow phosphor converter is one selected from a group consisting of a transmissive yellow phosphor plate and a transmissive yellow phosphor wheel.

10. The headlamp of claim 7, in which a portion of the phosphor-emitted light beam is unconverted blue laser light.

11. The headlamp of claim 7, in which the dichroic mirror is configured to reflect all blue light.

12. A method of generating a white light beam in an illumination apparatus, the method comprising:

providing a first blue light beam, wherein the first blue light beam is a blue laser light beam;

with a collimating lens, collimating the first blue light beam into a collimated blue light beam;

with an optical diffuser, optically homogenizing the collimated blue light beam into a top hat spatially distributed beam;

with a transmissive yellow phosphor converter, converting the top hat spatially distributed beam into a phosphor-emitted light beam having a same direction as the top hat spatially distributed beam, wherein most of the phosphor-emitted light beam is yellow light converted from blue light of the top hat spatially distributed beam;

condensing and collimating the phosphor-emitted light beam into a condensed and collimated phosphor-emitted light beam;

with a dichroic mirror, filtering the condensed and collimated phosphor-emitted light beam into a dichroic-filtered light beam passed by the dichroic mirror, the dichroic mirror configured to pass yellow light and to reflect at least some blue light;

providing a second blue light beam; and

with the dichroic mirror, reflecting the second blue light beam in a same direction as the dichroic-filtered light beam to generate the white light beam.