Method and apparatus for OCT-based viscometry
First Claim
1. A method for ascertaining a relative viscosity characterizing a fluid sample, the method comprising:
- a. illuminating the fluid sample through a scattering membrane adjacent to the fluid with broadband radiation having a fraction bandwidth, at half-maximum, of at least 10%;
b. detecting scattering from scattering particles within the fluid sample, the scattering particles characterized by a distribution of characteristic dimensions spanning at least two orders of magnitude;
c. generating a wavelength-resolved detector signal for deriving coherent scatter as a function of depth relative to a specified surface of the scattering membrane at a plurality of temporal delays;
d. interferometrically deriving at least one of amplitude, phase and intensity of a scattered optical field for a plurality of depths relative to the specified surface;
e. calculating a mean cross-correlation function for each depth;
f. fitting the mean cross-correlation function for the plurality of depths to obtain a diffusion coefficient; and
g. deriving the relative viscosity characterizing the fluid based on the diffusion coefficient.
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Abstract
Methods and apparatus for ascertaining a relative viscosity characterizing a fluid sample. The fluid sample is illuminated through a scattering membrane adjacent to the fluid with broadband radiation. Scattering from particles within the fluid sample characterized by a distribution of characteristic dimensions spanning at least two orders of magnitude is detected, generating a detector signal as a function of depth relative to a specified surface of the scattering membrane at a plurality of temporal delays. A cross-correlation function of at least one of amplitude, phase and intensity of a scattered optical field is derived for a plurality of depths relative to the specified surface. A mean cross-correlation function is then derived for each depth and fit to obtain a diffusion coefficient, from which a relative viscosity characterizing the fluid is derived.
18 Citations
6 Claims
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1. A method for ascertaining a relative viscosity characterizing a fluid sample, the method comprising:
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a. illuminating the fluid sample through a scattering membrane adjacent to the fluid with broadband radiation having a fraction bandwidth, at half-maximum, of at least 10%; b. detecting scattering from scattering particles within the fluid sample, the scattering particles characterized by a distribution of characteristic dimensions spanning at least two orders of magnitude; c. generating a wavelength-resolved detector signal for deriving coherent scatter as a function of depth relative to a specified surface of the scattering membrane at a plurality of temporal delays; d. interferometrically deriving at least one of amplitude, phase and intensity of a scattered optical field for a plurality of depths relative to the specified surface; e. calculating a mean cross-correlation function for each depth; f. fitting the mean cross-correlation function for the plurality of depths to obtain a diffusion coefficient; and g. deriving the relative viscosity characterizing the fluid based on the diffusion coefficient. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification