System and methods estimation of mechanical properties and size of light-scattering particles in materials
System and method for determining a viscoelastic modulus of a sample with the use of optical data and an average size of light-scattering particles, of such sample, that has been derived from the optical data in reliance of angular dependence of a radiant flux profile determined from laser speckles formed by the sample and, in required, on a refractive index mismatch between light-scattering particles and sample medium hosting such particles. The determination is optionally carried out by taking into account at least one of absorption coefficient and reduced scattering coefficient of the sample, which are also determined from the same optical data. Laser speckle may be formed for different combinations of polarization states of sample-illuminating light and detected light and/or different wavelengths to account for polydisperse nature of the sample.
1. A system for use in determining a viscoelastic modulus of a sample, the system comprising:
an optical illumination portion comprising at least one light source configured to deliver light to the sample;
an optical data acquisition portion including an optical detector configured to receive light, that has been delivered to the sample by the optical illumination portion and that has interacted with the sample, to acquire optical data representing scattering of said light by multiple light-scattering events within the sample; and
a processor operably cooperated with said optical data acquisition portion and programmed to:
determine a diffuse remittance profile (DRP) derived from the optical data,
determine a pattern of the DRP as a function of angle in a plane of an optical detector,
determine an average size of the light-scattering particles causing the multiple light-scattering events within the sample by comparing a first value with a map of second values,
the first value defined by a distribution of light irradiance in said pattern, and
the second values characterizing distributions of light irradiance across radiant flux profiles that have been theoretically calculated as functions of (i) a first variable representing average sizes of light-scattering particles and (ii) a second variable representing refractive index mismatch between the light-scattering particles and a medium containing said particles,
calculate a mean square displacement (MSD) value for said light-scattering particles and a mechanical property of the sample from the optical data, and
determine a viscoelastic modulus based on the size of the light-scattering particles and the MSD value for the light-scattering particles.
2. A system according to claim 1 , wherein the optical illumination portion includes a first optical polarizer unit; wherein the optical data acquisition portion includes a second optical polarizer unit, at least one of the first and second optical polarizer units variably defining respectively corresponding first and second polarization states of light transmitted therethrough, the first and second optical polarizer units disposed in optical communication such that light that has passed through the first optical polarizer unit interacts with the sample and then passes through the second optical polarizer unit towards the optical detector unit.
3. A system according to claim 2 , wherein at least one of the first and second optical polarizer units is configured to vary a polarization state of light propagating therethrough in response to an input applied to the at least one of the first and second optical polarizer units.
4. A system according to claim 3 , wherein the at least one of the first and second optical polarizer units includes at least one of an electro-optical material, a photo-elastic material, and a liquid-crystal material.
5. A system according to claim 2 , wherein the first optical polarizer unit defines a first state of polarization of light transmitted therethrough towards the sample, the second optical polarizer unit defines a second state of polarization of light transmitted therethrough towards the optical detector, the first and second states of polarization being equal.
6. A system according to claim 5 , wherein the first and second states of polarization include linear polarizations having corresponding vectors that are collinear, as viewed along a direction of propagation of light through the first and second optical polarizer units.
7. A system according to claim 5 , wherein the first and second states of polarization include linear polarizations having corresponding vectors that are transverse to one another, as viewed along a direction of propagation of light through the first and second optical polarizer units.
8. A system according to claim 1 , wherein a first optical axis of the optical illumination portion forms a first angle with respect to a surface of the sample, and a second optical axis defined by the optical data acquisition portion forms a second angle with respect to the surface, the first and second angles being different.
9. A system according to claim 1 , wherein the optical illumination portion includes at least one light source is configured to generate light at at least one wavelength.
10. A system according to claim 9 , wherein the at least one light source includes a wavelength-tunable laser source.
11. A system according to claim 9 , wherein the at least one light source includes a source of incoherent light.
12. A system according to claim 9 , wherein the at least one light source includes a broadband source of light.
13. A system according to claim 1 , wherein the optical illumination portion is configured to irradiate sample with light at multiple wavelengths, and wherein the DRP and the radiant flux profiles have been determined as functions of (iii) a third variable representing a wavelength of said light.
14. A system according to claim 13 , further comprising a tangible, non-transitory storage medium containing reference data representing said map of second values as a function of at least one of the first, second, and third variables.
15. A system according to claim 1 , wherein the first value is defined by first and second normalized irradiances determined, respectively, at first and second angles from said pattern.
16. A system according to claim 15 , wherein the first value is a ratio of said first and second normalized irradiances.
17. A system according to claim 1 , wherein the processor is further programmed to define a shape metric of said pattern, said shape metric including at least one of a shape of a pattern lobe, a pattern lobe width, an angle between lobes of the pattern, a number of pattern lobes, and a separation of a lobe peak from a center of said pattern.
18. A system according to claim 1 , wherein the processor is further programmed to calculate a value of the viscoelastic modulus of said sample from data that represents mean square displacements of the light-scattering particles of the sample.
19. A system according to claim 1 , wherein the processor is further programmed to derive from the optical data, when the sample includes blood, parameters of a blood coagulation cascade that include clotting time (CT) and at least one of total coagulation time, clot formation time (CFT), maximum clot firmness (MCF), maximum lysis (ML), percentage of lost clot stability at a selected point in time, rate of clotting, fibrinolysis time, clot compliance, and clot viscosity.
20. A system according to claim 1 , wherein the processor is further programmed to calculate at least one of an absorption coefficient and a reduced scattering coefficient of the sample based at least on the DRP determined from the optical data that have been averaged over time.
21. A method for determining a viscoelastic modulus of a sample with the use of an optical system, the method comprising:
acquiring, with an optical detector, optical data representing time evolution of a speckle associated with light-scattering particles of the sample irradiated with light from a light source;
determining an average size of said light-scattering particles based on an angle-dependent pattern of a diffuse remittance profile (DRP) derived from acquired optical data;
calculating, with a programmable processor, a value of mean square displacement (MSD) of the light-scattering particles and a mechanical property of the sample from the acquired optical data, said MSD being a function of said size; and
estimating, with the programmable processor and from said angle-dependent pattern, an experimentally-determined value of a ratio of a first normalized irradiance to a second normalized irradiance, the first and second normalized irradiances being defined by said angle-dependent pattern at first and second values of an angle, respectively.
22. A method according to claim 21 , further comprising determining an optical property of the sample based, in part, on the radiant flux profile determined from acquired optical data.
23. A method according to claim 22 , wherein determining an optical property includes calculating at least one of an absorption coefficient and a reduced scattering coefficient of the sample based at least on the radiant flux profile determined from the optical data that have been averaged over time.
24. A method according to claim 21 , further comprising determining a frequency-dependent value of viscoelastic modulus characterizing the sample based on said size and said MSD.
25. A method according to claim 21 , wherein said acquiring includes detecting light from a irradiance distribution formed at the optical detector by said light, that has interacted with the sample, by varying at least one of i) polarization state and ii) wavelength of said light, and said determining includes determining an averaged size of light-scattering particles of the sample.
26. A method according to claim 21 , further comprising defining an average size of said light-scattering particles based on comparison of the experimentally-determined value of ratio with a reference map, the reference map representing dependencies of values of said ratio theoretically-calculated as a function of average sizes for different values of a refractive index mismatch between a material of light-scattering particles and a material of the sample's medium in which said light-scattering particles are contained.
27. A method according to claim 26 , wherein said reference map represents dependencies of values of said ratio theoretically-calculated as a function of average sizes, said values of the refractive index mismatch, and optical wavelengths.
28. A method according to claim 21 , further comprising defining the first and second angles to maximize a change of the experimental value of a ratio per unit of a change in size of light-scattering particles.
29. A method according to claim 21 , wherein said acquiring includes detecting light in a sequence of images of the speckle, and further comprising calculating a value of the viscoelastic modulus from data that represents frequency-dependent MSD of said light-scattering particles and that is determined with the use of autocorrelation analysis from a sequence of speckle images, wherein said calculating includes accounting for said size.
30. A method according to claim 21 , wherein said acquiring includes detecting light from a laser speckle formed by light-scattering particles of a sample containing blood, and further comprising deriving from said optical data, with a programmed processor operably cooperated with said optical data acquisition system, parameters of a blood coagulation cascade, said parameters including clotting time (CT) and at least one of total coagulation time, clot formation time (CFT), maximum clot firmness (MCF), maximum lysis (ML), percentage of lost clot stability at a selected point in time, rate of clotting, fibrinolysis time, clot compliance, and clot viscosity.
31. A method according to claim 21 , further comprising varying at least one of a wavelength of light delivered to the sample and a polarization state of light propagating through the optical system.
32. A method according to claim 31 , wherein said varying includes changing an operational status of at least one of i) a polarizer of an illumination portion of the optical system and ii) an analyzer of the optical detection portion of the optical system.
33. A method according to claim 21 , further comprising calculating at least one of an absorption coefficient and a reduced scattering coefficient of the sample based at least on the DRP determined from the optical data that have been averaged over time.
34. A system for use in determining a viscoelastic modulus of a sample, the system comprising:
an optical illumination portion comprising a light source configured to deliver light to the sample;
an optical data acquisition portion including an optical detector to receive light that has been delivered to the sample by the optical illumination portion and that has interacted with the sample, and to acquire optical data representing scattering of said light by multiple light-scattering events within the sample; and
a processor operably cooperated with said optical data acquisition portion and programmed to:
determine an average size of said light-scattering particles causing the multiple light-scattering events based on an angle-dependent pattern of a diffuse remittance profile (DRP) based on the optical data,
calculate a mean square displacement (MSD) value for said light-scattering particles and a mechanical property of the sample from the optical data,
the MSD being a function of the size, and
estimate, from the angle-dependent pattern, an experimentally-determined value of a ratio of a first normalized irradiance to a second normalized irradiance,
the first and second normalized irradiances being defined by said angle-dependent pattern at first and second values of an angle, respectively.