Systems and methods for measuring particle size in tissue and turbid media

A method for determining a size of scattering particles in a sample comprising:

• illuminating the sample with a polarized light;
• capturing backscattered light from the sample to form a speckle pattern;
• analyzing the speckle pattern to determine attributes that include at least one of a ratio of intensities at orthogonal polarization states, a circularity measure, or a decorrelation rate ratio of speckle intensity modulations at parallel and orthogonal polarization states;
• applying the attributes to a model to determine an absorption coefficient or reduced absorption coefficient;
• using the absorption coefficient or reduced absorption coefficient to determine a cluster centroid and a size prediction model;
• and
• estimating the size of the scattering particles based on the cluster centroid and the attributes.

A system for determining a size of scattering particles in a sample, the system comprising:

• a light source configured to emit a polarized light beam;
• a sample stage for positioning the sample in a path of the polarized light beam;
• at least one camera positioned to capture backscattered light from the sample and form a speckle pattern;
• and
• a processing unit configured to:
• analyze polarization-dependent attributes of the speckle pattern to extract a set of attributes from the speckle pattern that include at least one of a ratio of intensities along a short and long axis of parallel polarized back-scattered light, a circularity of an intensity envelope at orthogonal polarization states, a decorrelation rate ratio, or a radial extend of the intensity envelope;
• use an absorption coefficient or reduced absorption coefficient to determine a centroid coordinates and a size prediction model;
• and
• estimate the size of the scattering particles based on a cluster centroid and the extracted attributes.

A method for determining the size of scattering particles in a sample comprising:

• illuminating the sample with a polarized light;
• capturing backscattered light from the sample to form a speckle pattern;
• analyzing the speckle pattern to determine attributes that include at least one of a ratio of intensities along the long and short axes of intensity envelope at the parallel polarization state, a circularity of the intensity envelope at orthogonal polarization states, a decorrelation rate ratio of speckle intensity modulations at parallel and orthogonal polarization states, or a radial extent of the intensity envelope at orthogonal polarization states;
• applying the attributes to a clustering approach that assigns the four-tupled attribute vector to one of five clusters;
• and
• estimating the size of the particles based on a regression model of the said cluster, without the need to estimate or know the optical properties.