Tracking and characterizing particles with holographic video microscopy
First Claim
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1. A method for characterizing a specimen, comprising:
- providing a holographic microscope;
selecting multiple wavelengths for a laser;
scattering the laser'"'"'s beam off the specimen to generate a scattered portion;
generating an interference pattern from an unscattered portion of the collimated laser beam and the scattered portion;
recording the interference pattern for subsequent analysis;
applying a Lorenz-Mie scattering function to calculate a hologram and fitting the recorded interference pattern to the calculated hologram; and
determining an estimate of the specimen'"'"'s refractive index and radius from the fitted calculated hologram;
wherein the determining of the refractive index of the specimen comprises measuring refractive indices of the specimen at each of the multiple wavelengths.
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Abstract
In-line holography to create images of a specimen, such as one or more particles dispersed in a transparent medium. Analyzing these images with results from light scattering theory yields the particles'"'"' sizes with nanometer resolution, their refractive indexes to within one part in a thousand, and their three dimensional positions with nanometer resolution. This procedure can rapidly and directly characterize mechanical, optical and chemical properties of the specimen and its medium.
30 Citations
14 Claims
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1. A method for characterizing a specimen, comprising:
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providing a holographic microscope; selecting multiple wavelengths for a laser; scattering the laser'"'"'s beam off the specimen to generate a scattered portion; generating an interference pattern from an unscattered portion of the collimated laser beam and the scattered portion; recording the interference pattern for subsequent analysis; applying a Lorenz-Mie scattering function to calculate a hologram and fitting the recorded interference pattern to the calculated hologram; and determining an estimate of the specimen'"'"'s refractive index and radius from the fitted calculated hologram; wherein the determining of the refractive index of the specimen comprises measuring refractive indices of the specimen at each of the multiple wavelengths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer implemented system comprising:
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a holographic microscope apparatus comprising a coherent light source with multiple discrete concurrent wavelengths of coherent light beams'"'"' a specimen stage, an objective lens, and an image collection device; a computer module in communication with the holographic microscope apparatus and including a processor and memory, the memory receiving image data from the image collection device and further having a set of instructions for; selecting multiple wavelengths for a laser; scattering the laser'"'"'s beam off the specimen to generate a scattered portion; generating an interference pattern from an unscattered portion of the collimated laser beam and the scattered portion; recording the interference pattern for subsequent analysis; applying a scattering function to analyze the recorded interference pattern wherein the scattering function comprises a Lorenz-Mie function; normalizing the interference pattern by dividing the interference pattern by a background form of interference pattern; fitting a calculated hologram to the interference pattern; and determining an estimate of the specimen'"'"'s refractive index and radius from the fitted calculated hologram; wherein the determining of the refractive index of the specimen comprises measuring refractive indices of the specimen at each of the multiple wavelengths. - View Dependent Claims (12, 13, 14)
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Specification