Method and apparatus for combining measurements of particle characteristics using light scattering and optical imaging
The present invention comprises methods and apparatus for measuring light scattering from particles and images of particles, and for combining size distributions from the measurements to produce a single size distribution over a larger size range.
1. An apparatus which determines a particle size distribution from scattering measurements of particles and imaging of particles comprising:
a) at least one light source which illuminates particles,
b) at least one scatter detector which detects light scattered from particles over a range of scattering angles,
c) a plurality of imaging detectors which detect an image of each of a plurality of particles,
d) means which determines a first particle size distribution from said detection of scattered light from particles,
e) means which determines a second particle size distribution from said detection of images of particles,
f) combining means which combines said first particle size distribution and said second particle size distribution to create a third particle size distribution with larger size range, wherein said third particle size distribution comprises three size regions which comprise a small size region, a size overlap region, and a large size region, wherein said third particle size distribution, in said small size region, is derived from a portion of said first particle size distribution, wherein said third particle size distribution, in said large size region, is derived from a portion of said second particle size distribution, and wherein said third particle size distribution, in said size overlap region, is derived from said first particle size distribution and said second particle size distribution, comprising the following means,
g) means which places said first particle size distribution and said second particle size distribution onto the same scale and/or onto the same size distribution parameter, and
h) means which combines said first particle size distribution and said second particle size distribution in said size overlap region to create said third particle size distribution in said size overlap region by utilizing a generally monotonic function of particle size.
2. The apparatus of claim 1 , wherein said at least one scatter detector comprises a plurality of detectors to measure scattered light over a plurality of ranges of scattering angle.
3. The method of claim 1 wherein said generally monotonic function comprises a linear function.
4. A method which determines a particle size distribution from scattering measurements of particles and imaging of particles comprising:
a) illuminating particles,
b) detecting light scattered from particles over at least one range of scattering angle,
c) detecting an image of each of a plurality of particles,
d) determining a first particle size distribution from said detection of scattered light from particles,
e) determining a second particle size distribution from said detection of particle images,
f) combining said second particle size distribution and said first particle size distribution to create a third particle size distribution with larger size range, wherein said third particle size distribution comprises three size regions which comprise a small size region, a size overlap region, and a large size region, wherein said third particle size distribution, in said small size region, is derived from a portion of said first particle size distribution, wherein said third particle size distribution, in said large size region, is derived from a portion of said second particle size distribution, and wherein said third particle size distribution, in said size overlap region, is derived from said first particle size distribution and said second particle size distribution, comprising the following steps,
g) placing said first particle size distribution and said second particle size distribution onto the same scale and/or onto the same size distribution parameter, and
h) combining said first particle size distribution and said second particle size distribution in said size overlap region to create said third particle size distribution in said size overlap region by utilizing a generally monotonic function of particle size.
5. The method of claim 4 wherein said scattered light detecting utilizes a plurality of detectors to measure scattered light over a plurality of ranges of scattering angle.
6. The method of claim 4 wherein said generally monotonic function comprises a linear function.