Method and system for measuring porosity of particles

Patent metadata

Field	Value
Publication number	US-2017191920-A1
Application number	US-201615376274-A
Country	US
Kind code	A1
Filing date	Dec 12, 2016
Priority date	Nov 5, 2010
Publication date	Jul 6, 2017
Grant date	—

Abstract

A method for analyzing porosity of a particle and a medium disposed in the porosity of the particle. A video-holographic microscope is provided to analyze interference patterns produced by providing a laser source to output a collimated beam, scattering the collimated beam off a particle and interacting with an unscattered beam to generate the interference pattern for analyzation to determine the refractive index of the particle and a medium disposed in the porosity of the particle to measure porosity and the medium.

First claim

1 . A method of analyzing characteristics of a particle in suspension, comprising the steps of:
providing a particle in a suspension medium; providing a video holographic microscope; providing a laser source for producing a collimated output beam; scattering the collimated output beam off the particle to generate a scattered beam and a combination of the scattered beam and an unscattered portion of the output beam to generate an interference pattern; recording intensity of the interference pattern for analysis; analyzing the interference pattern to determine refractive index of the particle; and comparing characteristics of an average of a bulk form of the material composing the particle to the particle refractive index to characterize parameters of the particle and the suspension medium.

2 . The method as defined in claim 1 wherein the step of analyzing comprises determining the refractive index and then performing the comparing step to establish at least one of porosity of the particle and character of the suspension medium disposed in pores of the particle.

3 . The method as defined in claim 1 wherein the step of analyzing the interference pattern comprises applying a Lorenz-Mie formalism to determine the refractive index of the particle.

4 . The method as defined in claim 1 further including the step of analyzing the interference pattern during growth of the particle, thereby enabling characterization of development of porosity in the particle.

5 . The method as defined in claim 3 wherein the Lorenz-Mie formalism comprises,
I ( r )=| E 0 ( r )+ E 0 ( r p ) f s ( k ( r−r p ))| 2 ,
where I(r) is intensity of the interference pattern recorded at position r, E 0 (r) is the electric field of the output laser at position r, r p is the position of the particle, k is the wavenumber of the light, and f s (kr) is the Lorenz-Mie scattering function that describes scattering of light by the particle and wherein the Lorenz-Mie scattering function depends on radius of the particle, a p , effective refractive index n p of the particle.

6 . The method as defined in claim 5 where the effective refractive index n p of the particle depends on refractive index n 1 of the material from which the particle is composed, porosity p of the particle, and refractive index n 2 of the medium that fills the pores within the particle.

7 . The method as defined in claim 6 where the porosity p of the particle is related to the effective refractive index of the particle, n p , the refractive index n 1 of the bulk material from which the particle is composed and the refractive index n 2 of the material filling the particle's pores according to

p
=

f


(

n
p

)

-

f


(

n
2

)

f


(

n
1

)

-

f


(

n
2

)

,

where

f


(
n
)

=

n
2

-
1

n
2

+
2

.

8 . The method as defined in claim 1 further including a computer system for executing computer software to carry out the steps of analyzing the interference pattern and comparing the refractive index of the bulk to the refractive index of the particle.

9 . A method of analyzing a medium disposed in a particle in suspension, comprising the steps of:
providing a video holographic microscope; providing a laser source for producing a collimated output beam; scattering the collimated output beam off the particle to generate a scattered beam and a combination of the scattered beam and an unscattered portion of the output beam to generate an interference pattern; recording intensity of the interference pattern for analysis; analyzing the interference pattern to determine refractive index of the particle; and comparing refractive index of an average of a bulk form of the particle to the refractive index of the particle in the suspension to determine a measure of the medium disposed in porosity of the particle.

10 . The method as defined in claim 9 wherein the step of analyzing the interference pattern comprises applying a Lorenz-Mie formalism to determine the refractive index of the particle containing the medium.

11 . The method as defined in claim 9 further including the step of analyzing the interference pattern during growth of the particle, thereby enabling characterization of development of the medium disposed in the porosity in the particle.

12 . The method as defined in claim 10 wherein the Lorenz-Mie formalism comprises,
I ( r )=| E 0 ( r )+ E 0 ( r p ) f s ( k ( r−r p ))| 2 .
where I(r) is intensity of the interference pattern recorded at position r, E 0 (r) is the electric field of the output laser at position r, r p is the position of the particle, n m is the refractive index of the medium disposed in the porosity of the particle, k is the wavenumber of the light, and f s (kr) is the Lorenz-Mie scattering function that describes scattering of light by the particle, wherein the Lorenz-Mie scattering function depends on radius of the particle, a p , effective refractive index n p of the particle.

13 . The method as defined in claim 9 further including a computer system for executing computer software to carry out the steps of analyzing the interference pattern and comparing the refractive index of the bulk to the refractive index of the particle with the medium disposed in the porosity.

14 . The method as defined in claim 12 wherein n m is selected from the group consisting of the refractive index of a suspension fluid wetting the particle and n m =1 wherein the

Assignees

• Univ New York
• Nat Science Found

Inventors

• Cheong Fook Chiong
• Xiao Ke
• Pine David
• Grier David G

Classifications

• G01N15/1463

  Physics · mapped topic

• G01N21/453

  Holographic interferometry (for dimensional measurements G01B9/021 - G01B9/029) · CPC title

• G01N15/088 Primary

  Investigating volume, surface area, size or distribution of pores; Porosimetry · CPC title

• G02B21/367

  providing an output produced by processing a plurality of individual source images, e.g. image tiling, montage, composite images, depth sectioning, image comparison · CPC title

• G01N2015/0846

  by use of radiation, e.g. transmitted or reflected light · CPC title