Speckle contrast system and method that discriminates photons path lengths

Patent metadata

Field	Value
Publication number	US-2020141798-A1
Application number	US-201916670207-A
Country	US
Kind code	A1
Filing date	Oct 31, 2019
Priority date	Nov 2, 2018
Publication date	May 7, 2020
Grant date	—

Abstract

Speckle contrast method and system that discriminates photons based on their path length in tissue, the method comprising the steps of:
directing light from a pulsed light into a sample by optical elements; synchronizing the time between the pulse injection to sample and the detection unit; collecting the photons that have travelled through the sample by optics, and conveying the photons of a single or a limited number of speckles from the sample to one or more detection elements; time-tagging photons thanks to the synchronization of the detector element and/or the time-tagging electronics with the laser pulse emission; estimating each photon time-of-flight by the difference between its time tag and the laser pulse emission; categorizing the detected photons based on the value of the time-of-flight in a certain number of time gates; measuring the speckle contrast

First claim

1 . A speckle contrast optical spectroscopy system for discriminating photons based on their path length in a sample, the system comprising:
a coherent pulsed light source for producing light pulses; a time-gated detector; a means for synchronizing the time between the source and the time gated detector; an optical means for directing the light pulses towards a sample; an optical means for collecting the light once it has travelled the sample and directing it towards the time-gated detector; and a computer means for calculating the speckle contrast from the collected photons and for resolving the photons in time.

2 . The speckle contrast optical spectroscopy system according to claim 1 wherein the means for producing a synchronized signal are a beam splitter and a photodiode, a laser or a clock.

3 . The speckle contrast optical spectroscopy system according to claim 1 wherein the detection means are adapted to be turned on and off at a time-scale that allows to accept or to reject predefined photon path lengths.

4 . The speckle contrast optical spectroscopy system according to claim 1 wherein the time-gated detector is a free running detector element with a time-tagging electronics, or a fast-gated detector element, or a fast-gated detector provided with a time-tagging electronics.

5 . A method for discriminating photons based on their path length in tissue, the method comprising the steps of:
directing light from a pulsed light source into a sample by optical elements; synchronizing the time between the pulse injection to sample and the detection unit; collecting the photons that have travelled through the sample by optics, and conveying the photons of a single or a limited number of speckles from the sample to one or more detection elements; time-tagging photons by the synchronization of the detector element and/or the time-tagging electronics with the laser pulse emission; estimating each photon time-of-flight by the difference between its time tag and the laser pulse emission; categorizing the detected photons based on the value of the time-of-flight in a certain number of time gates; measuring the speckle contrast for each categorized set of recorded photons intensity at the detector; and comparing measured speckle contrast iteratively to a modeled speckle contrast, which has the scatterer dynamics as free parameter.

6 . The speckle contrast optical spectroscopy system according to claim 2 wherein the detection means are adapted to be turned on and off at a time-scale that allows to accept or to reject predefined photon path lengths.

7 . The speckle contrast optical spectroscopy system according to claim 2 wherein the time-gated detector is a free running detector element with a time-tagging electronics, or a fast-gated detector element, or a fast-gated detector provided with a time-tagging electronics.

8 . The speckle contrast optical spectroscopy system according to claim 3 wherein the time-gated detector is a free running detector element with a time-tagging electronics, or a fast-gated detector element, or a fast-gated detector provided with a time-tagging electronics.

9 . The speckle contrast optical spectroscopy system according to claim 6 wherein the time-gated detector is a free running detector element with a time-tagging electronics, or a fast-gated detector element, or a fast-gated detector provided with a time-tagging electronics.

Assignees

• Fundacio Inst De Ciencies Fotòniques
• Inst Catalana Recerca Estudis Avancats

Inventors

• Durduran Turgut
• Vidal Rosas Ernesto
• Pagliazzi Marco

Classifications

• A61B5/0059 Primary

  using light, e.g. diagnosis by transillumination, diascopy, fluorescence (photoacoustic A61B5/0093; optical measurement of heart rate A61B5/02416; optical measurement of blood flow A61B5/0261; optical measurement of analytes A61B5/1455) · CPC title

• G01N2021/479

  Speckle · CPC title

• A61B5/0075

  by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence) · CPC title

• A61B5/0261

  using optical means, e.g. infrared light · CPC title

• G01J3/027 Primary

  Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation · CPC title