Apparatus for measuring particle size distribution and method for analyzing particle size distribution

A method for measuring a particle size distribution, said method comprising the steps of:

• directing a laser light to particles which are dispersed into a solvent and which exhibit Brownian motion;
• converting an interference light caused by Doppler-shifted scattered light by the particles into an electric detection signal;
• processing the detected signal to obtain an interim function, followed by inversely operating the interim function to calculate a particle size distribution, wherein said method further comprising the steps of:
• selecting data from all data regions in the interim function at appropriate intervals;
• creating a data table used in the inverse problem;
• and
• obtaining the particle size distribution from the table.

A method for analyzing a particle size distribution, said method comprising the steps of:

• directing a laser light to particles which are dispersed into a solvent and which exhibit Brownian motion;
• converting an interference light caused by Doppler-shifted scattered light by the particles into an electric detection signal;
• subjecting the intermediate function to an inverse problem and thereby calculating a particle size distribution, wherein said method further comprising the steps of:
• while presetting an assumed particle size distribution, calculating frequency characteristics of the detection signal and setting the frequency characteristics as measured frequency characteristics;
• calculating the frequency characteristics of a Lorenzian function having a half-width obtained by a Stokes-Einstein expression from measurement conditions in accordance with particle sizes and setting the frequency characteristics of the Lorenzian function as operation frequency characteristics;
• calculating a response function indicating a light intensity with respect to a particle size based on the operation frequency characteristics for every frequency;
• calculating the frequency characteristics based on assumed values in the assumed particle size distribution for every frequency using the response function as a weight;
• correcting the assumed particle size distribution in accordance with a rate of a difference between the frequency characteristics based on the assumed values and the measured frequency characteristics;
• repeating said processing steps using the corrected assumed particle size distribution;
• determining, as a true particle size distribution, the assumed particle size distribution when the rate of the difference between the frequency characteristics based on the assumed values and the measured frequency characteristics falls within a predetermined range.

A method for analyzing a particle size distribution, said method comprising the steps of:

• directing a laser light to particles which are dispersed into a solvent and which exhibit Brownian motion;
• converting an interference light caused by Doppler-shifted scattered light by the particles into an electric detection signal;
• subjecting the intermediate function to an inverse problem and thereby calculating a particle size distribution, wherein said method further comprising the steps of:
• while presetting an assumed particle size distribution, calculating an autocorrelation function of the detection signal and setting the autocorrelation function as a measured autocorrelation function;
• calculating an autocorrelation function of an exponential function having a time constant obtained by a Stokes-Einstein expression from measurement conditions in accordance with a particle size and setting the autocorrelation function as an operation autocorrelation function;
• calculating a response function indicating a light intensity with respect to a particle size based on the operation autocorrelation function for every delay time;
• calculating the autocorrelation function based on assumed values in the assumed particle size distribution for every delay time using the response function as a weight;
• correcting the assumed particle size distribution in accordance with a rate of a difference between the autocorrelation function based on the assumed values and the measured autocorrelation function;
• repeating said processing steps using the corrected assumed particle size distribution;
• determining, as a true particle size distribution, the assumed particle size distribution when the rate of the difference between the autocorrelation function based on the assumed values and the measured autocorrelation function falls within a predetermined range.