Automated real-time particle characterization and three-dimensional velocimetry with holographic video microscopy
AssigneeNew York University
InventorsDavid G. Grier, Fook Chiong Cheong, Ke Xiao
Life of this patent
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Abstract
An in-line holographic microscope can be used to analyze on a frame-by-frame basis a video stream to track individual colloidal particles' three-dimensional motions. The system and method can provide real time nanometer resolution, and simultaneously measure particle sizes and refractive indexes. Through a combination of applying a combination of Lorenz-Mie analysis with selected hardware and software methods, this analysis can be carried out in near real time. An efficient particle identification methodology automates initial position estimation with sufficient accuracy to enable unattended holographic tracking and characterization.
Claims19
A method of characterizing a parameter of a sample by holographic microscopy, comprising the steps of:
- receiving holographic image data of the sample from a storage medium;
- determining a first estimate of the number of objects in the holographic image data, each object associated with a set of concentric bright and dark rings;
- determining, for each set of concentric bright and dark rings, by a voting algorithm, a centroid defined by an approximate x, y position in a plane, with each pixel of the image data voting for pixels in a transformed image that may be centroids;
- determining an estimate of the axial position (z) of each of the objects;
- determining by Lorenz-Mie analysis an estimate of each of the objects' radius and refractive index;
- using holographic image data from the sample to characterize properties of the sample and generate information characteristic of the parameters of the sample;
- and
- comparing the estimate of each object's radius with control holographic image data corresponding to a known radius of a control object.
A system for characterizing a parameter of a sample by holographic microscopy, comprising:
- a holographic microscope including a laser beam source and an objective lens, the laser beam scattering from the sample and interacting with an unscattered portion of the laser beam to provide a holographic scattering pattern;
- an image collection device for collecting image data characteristic of the scattering pattern from the holographic microscope;
- and
- a computer system including a processor and memory, the memory having stored thereon computer readable instructions, the computer readable instructions configured to:
- analyze the image data via computer software executed by the computer system, the computer software including a Lorenz-Mie methodology and executed by a graphical processing unit to provide substantially real time output of parameters characteristic of the sample;
- receive holographic image data of the sample;
- determine a first estimate of the number of objects in the holographic image data, each object associated with a set of concentric bright and dark rings;
- determine, for each set of concentric bright and dark rings, by a voting algorithm, a centroid defined by an approximate x, y position in a plane, with each pixel of the image data voting for pixels in a transformed image that may be centroids;
- determine an estimate of the axial position (z) of each of the objects;
- determine by Lorenz-Mie analysis an estimate of each of the objects' radius and refractive index;
- compare one of the radius and refractive index for each of the objects the same of radius or refractive index of a control uncoated sample;
- and
- determine for each one of the objects if that one object is coated.
A method of characterizing a parameter of a sample by holographic microscopy, comprising the steps of:
- receiving multicolor holographic image data of the sample from a storage medium;
- determining a first estimate of the number of objects in the holographic image data, each object associated with a set of concentric bright and dark rings;
- determining, for each set of concentric bright and dark rings, by a voting algorithm, a centroid defined by an approximate x, y position in a plane, with each pixel of the image data voting for pixels in a transformed image that may be centroids;
- determining an estimate of the axial position (z) of each of the objects;
- determining by Lorenz-Mie analysis an estimate of each of the objects' radius, refractive index;
- using holographic image data from the sample to characterize properties of the sample and generate information characteristic of the parameters of the sample;
- and
- analyzing the information characteristic of the sample parameters and determining in real time simultaneously size, position and refractive index of a particle of the sample.
Dependencies are inferred from the claim text.