Microns to Measure offers two techniques for
	particle size determination, covering the micron and
	sub-micron size ranges. Both techniques rely on the
	observation of light scattering from particles in 
	suspension to provide an absolute measure of 
	particle size.

	Sieves (Endecott) are used to determine particle size
	in the range above 1mm.

Principle:

The angular distribution of the light scattered from fine particles depends on their size (and other properties). From measurements of the scattering pattern we can calculate the size distribution.

Very fine particles in suspension are subject to Brownian motion and this random movement affects the intensity of light scattered from them. By measuring the rate of variation we can calculate the size distribution.

Sample Presentation:

The material is dispersed as a dilute suspension, usually in water. Other fluids or air can also be used.

The material is dispersed as a very dilute suspension in water or other fluids.

Data Analysis:

The size distribution is calculated using an optical model which describes the physics of the scattering process. Mie theory models require knowledge of the optical properties of the sample material. The simpler Fraunhofer model can be used with larger particles.

The size distribution which best fits the observations is determined mathematically. The Contin procedure is most commonly used.

Reports:

The size distribution can be reported in terms of particle number, area or volume; the latter, equivalent to mass, is most common.
Distributions may be presented as graphs and/or tables.
Various statistics may be calculated, including mean, median, CV, specific surface area.
Reports can be customised to the client's needs.

Typical Applications:

minerals, powders, suspensions, food products, emulsions, etc.

latex, paints, pigments, pharmaceuticals, fine emulsions, colloids.