TUNABLE SPECTRAL ILLUMINATOR FOR CAMERA

• US 20200137324A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: AKKAYA, Onur Can, ORTIZ EGEA, Sergio, BAMJI, Cyrus Soli
• Granted Patent: US 10,931,894 B2
• Time in Patent Office: Days
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/12 Generating the spectrum; Monochromators
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/32 Investigating bands of a spectrum in sequence by a single detector
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G02F 1/213 Fabry-Perot type
• CPC Class Codes: G02F 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths

Abstract

A camera includes one or more spectral illuminators, a tunable optical filter optically intermediate the one or more spectral illuminators and a scene, and a sensor array. The one or more spectral illuminators are configured to emit active spectral light. The tunable optical filter is dynamically adjustable to change a selected sub-band of the active spectral light that illuminates the scene. The sensor array includes a plurality of sensors each configured to measure spectral light reflected from the scene in the selected sub-band.

Claims

1. A camera comprising:

one or more spectral illuminators configured to emit active spectral light;

a tunable optical filter optically intermediate the one or more spectral illuminators and a scene, the tunable optical filter dynamically adjustable to change a selected sub-band of the active spectral light that illuminates the scene;

a sensor array including a plurality of sensors; and

a spectral controller machine configured to;

dynamically adjust the tunable optical filter to selectively transmit a selected sub-band of the active spectral light to illuminate the scene,

for at least one spectral illuminator, activate the spectral illuminator if the spectral illuminator is configured to emit active spectral light in the selected sub-band, and

address the sensors of the sensor array to measure spectral light reflected from the scene in the selected sub-band.

2. The camera of claim 1, wherein the tunable optical filter includes a Fabry-Perot interferometer comprising an optical cavity formed between a first reflective surface and a second reflective surface.

3. The camera of claim 2, wherein the Fabry-Perot interferometer is configured to change the sub-band of active spectral light that illuminates the scene by adjusting a length of the optical cavity.

4. The camera of claim 2, wherein the optical cavity includes liquid crystal material, and wherein the Fabry-Perot interferometer is configured to change the sub-band of active spectral light that illuminates the scene by changing a refractive index of the liquid crystal material.

5. The camera of claim 4, wherein the liquid crystal material is polarization sensitive, and wherein the one or more spectral illuminators are configured to emit active spectral light with a polarization that substantially matches a polarization of the liquid crystal material.

6. The camera of claim 1, wherein the tunable optical filter is configured to substantially block active spectral light outside of the selected sub-band.

7. The camera of claim 1, wherein the one or more spectral illuminators includes a broad-band spectral illuminator.

8. The camera of claim 1, wherein the one or more spectral illuminators includes a plurality of spectral illuminators, at least one spectral illuminator configured to emit active spectral light in a different sub-band.

9. The camera of claim 8, wherein sequentially one at a time for each of a plurality of spectral illuminators configured to emit different spectral light sub-bands, the spectral controller machine is configured to:

activate a spectral illuminator,

dynamically adjust the tunable optical filter to selectively transmit a sub-band that the spectral illuminator is configured to emit, and

address the sensors of the sensor array to measure spectral light reflected from the scene in the sub-band.

10. The camera of claim 9, wherein the spectral controller machine is configured to:

for each of the plurality of spectral illuminators, deactivate the spectral illuminator if the spectral illuminator does not emit active spectral light in the sub-band.

11. The camera of claim 1, wherein the selected sub-band is a first selected sub-band, and wherein the spectral controller machine is configured to:

dynamically adjust the tunable optical filter to selectively transmit a second selected sub-band within a spectral band of the at least one spectral illuminator, and

address the sensors of the sensor array to measure spectral light reflected from the scene in the second selected sub-band.

12. The camera of claim 1, further comprising:

an array of collimating lenses operatively intermediate the one or more spectral illuminators and the tunable optical filter, the array of collimating lenses configured to collimate the active spectral light emitted by the one or more spectral illuminators, and wherein the tunable optical filter receives substantially collimated active spectral light from the array of collimating lenses.

13. The camera of claim 1, further comprising:

an IR illuminator configured to emit active IR light in an IR light sub-band;

an optical shutter positioned in between the sensor array and the scene; and

a depth controller machine configured to;

adjust the optical shutter to transmit IR light in the IR light sub-band from the scene to the sensor array and block light outside of the IR sub-band;

activate the IR illuminator to illuminate the scene with the active IR light, address the sensors of the sensor array to measure an aspect of the active IR light emitted from the IR illuminator and reflected from the scene, and

determine, for each of the sensors, a depth value based on the measured aspect of the active IR light.

14. The camera of claim 13, wherein the spectral controller machine is configured to:

determine a surface normal of an imaged surface based on the depth value.

15. The camera of claim 13, wherein the spectral controller machine is configured to:

determine a spectral signature of an imaged surface based on the depth value and the measured spectral light.

16. An image acquisition method for a camera including one or more spectral illuminators configured to emit active spectral light and a tunable optical filter operatively intermediate the one or more spectral illuminators and a scene, the method comprising:

dynamically adjusting the tunable optical filter to selectively transmit a selected sub-band of the active spectral light to illuminate the scene;

for at least one of the one or more spectral illuminators, activating the spectral illuminator if the spectral illuminator is configured to emit active spectral light in the selected sub-band; and

addressing sensors of a sensor array of the camera to measure spectral light reflected from the scene in the selected sub-band.

17. The method of claim 16, wherein the camera includes a plurality of spectral illuminators, each spectral illuminator configured to emit spectral light in a different sub-band, and wherein the method comprises sequentially one at a time for at least one of the plurality of spectral illuminators:

activating the spectral illuminator;

dynamically adjusting the tunable optical filter to selectively transmit a sub-band that the spectral illuminator is configured to emit; and

addressing the sensors of the sensor array to measure spectral light reflected from the scene in the sub-band.

18. The method of claim 17, wherein the method further comprises:

for each of the plurality of spectral illuminators, deactivating the spectral illuminator if the spectral illuminator does not emit active spectral light in the sub-band.

19. The method of claim 17, further comprising:

adjusting an optical shutter positioned in between the sensor array and the scene to transmit IR light in the IR light sub-band from the scene to the sensor array and block light outside of the IR sub-band;

activating an IR illuminator of the camera to illuminate the scene with the active IR light;

addressing the sensors of the sensor array to measure an aspect of the active IR light emitted from the IR illuminator and reflected from the scene; and

determining, for each of the sensors, a depth value based on the measured aspect of the active IR light.

20. A camera comprising:

one or more spectral illuminators configured to emit active spectral light;

a Fabry-Perot interferometer optically intermediate the one or more spectral illuminators and a scene, the Fabry-Perot interferometer dynamically adjustable to change a selected sub-band of the active spectral light that illuminates the scene; and

a sensor array including a plurality of sensors each configured to measure spectral light reflected from the scene in the selected sub-band.