Time domain-based optical measurement systems and methods configured to measure absolute properties of tissue

Patent metadata

Field	Value
Publication number	US-12029558-B2
Application number	US-202117176560-A
Country	US
Kind code	B2
Filing date	Feb 16, 2021
Priority date	Feb 21, 2020
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

A wearable module for use in an optical measurement system includes a light guide configured to receive a light pulse from a light source and guide signal photons included in the light pulse toward a target within a body of a user, and a light diverter configured to divert reference photons included in the light pulse toward at least one detector configured to detect the reference photons.

First claim

What is claimed is:

1. A wearable module for use in an optical measurement system, the wearable module comprising:
a light guide configured to receive a light pulse from a light source and guide signal photons included in the light pulse toward a target within a body of a user when the wearable module is worn by the user;
at least one detector configured to detect the signal photons after the signal photons are scattered by the target when the wearable module is worn by the user;
a light diverter arranged so that, when the wearable module is worn by the user, the light diverter diverts reference photons included in the light pulse toward the at least one detector without the reference photons entering the target; and
a processing unit configured to:
determine a temporal distribution of the signal photons detected by the at least one detector;
determine a temporal distribution of the reference photons detected by the at least one detector; and
generate measurement data based on the temporal distribution of the signal photons and the temporal distribution of the reference photons.

2. The wearable module of claim 1 , wherein the light diverter is integrally formed with the light guide.

3. The wearable module of claim 2 , wherein the light diverter comprises a notch formed in an outer surface of the light guide.

4. The wearable module of claim 2 , wherein the light diverter comprises a protrusion formed in an outer surface of the light guide.

5. The wearable module of claim 1 , wherein the light diverter is separate from the light guide.

6. The wearable module of claim 1 , wherein:
the light guide comprises a plurality of optical fibers, and
the light diverter comprises at least one optical fiber included in the plurality of optical fibers.

7. The wearable module of claim 1 , wherein:
the at least one detector comprises a plurality of detectors; and
the light diverter is configured to divert a set of the reference photons toward each detector included in the plurality of detectors.

8. The wearable module of claim 1 , wherein the light diverter is configured to direct the reference photons toward the at least one detector by way of at least one optical element.

9. The wearable module of claim 1 , wherein the processing unit is further configured to determine, based on the measurement data, one or more of an absolute value of a reduced scattering coefficient μs′ of the target or an absolute value of an absorption coefficient μa of the target.

10. The wearable module of claim 1 , wherein the processing unit is further configured to determine, based on the measurement data, an absolute optical pathlength of the signal photons through the body.

11. The wearable module of claim 1 , wherein the processing unit is further configured to measure a time difference between an occurrence of a reference output pulse generated by the at least one detector and a signal output pulse generated by the at least one detector, the reference output pulse indicating that the at least one detector has detected a reference photon and the signal output pulse indicating that the at least one detector has detected a signal photon.

12. The wearable module of claim 1 , wherein an optical pathlength of the signal photons from the light diverter to a distal end of the light guide is 50 millimeters or less.

13. The wearable module of claim 1 , wherein an optical pathlength of reference photons detected by the at least one detector is less than an optical pathlength of signal photons detected by the at least one detector.

14. The wearable module of claim 1 , wherein the light diverter is movable relative to the at least one detector.

15. The wearable module of claim 1 , wherein the wearable module is included in a head-mountable component configured to be worn on a head of the user.

16. The wearable module of claim 15 , wherein the head-mountable component comprises a plurality of wearable modules.

17. The wearable module of claim 1 , wherein the target comprises a brain of the user.

18. The wearable module of claim 1 , wherein the at least one detector comprises a plurality of single-photon avalanche diode (SPAD) circuits.

19. The wearable module of claim 1 , further comprising:
at least one detector assembly arranged so that, when the wearable module is worn by the user, the at least one detector assembly receives the signal photons after the signal photons are scattered by the target and guides the signal photons to the at least one detector.

20. The wearable module of claim 19 , wherein the light diverter is configured to divert the reference photons to the at least one detector by way of at least one optical element included in the at least one detector assembly.

21. The wearable module of claim 20 , wherein the at least one detector assembly is movable relative to the light diverter.

22. The wearable module of claim 1 , further comprising the light source, wherein the light source comprises:
a first light source configured to emit a first light pulse in a first wavelength; and
a second light source configured to emit a second light pulse in a second wavelength that is different from the first wavelength.

Assignees

• Hi Llc

Inventors

• Katnani Husam
• Perdue Katherine
• Field Ryan
• Olvera Isai

Classifications

• A61B5/4088

  Diagnosing of monitoring cognitive diseases, e.g. Alzheimer, prion diseases or dementia · CPC title

• A61B2090/3614

  using optical fibre · CPC title

• A61B2562/0238

  Optical sensor arrangements for performing transmission measurements on body tissue · CPC title

• A61B2090/306

  using optical fibres · CPC title

• A61B5/6803 Primary

  Head-worn items, e.g. helmets, masks, headphones or goggles · CPC title