Laser Diffraction

Laser Diffraction (also known as Static Light Scattering) is one of the most widely used particle sizing distribution techniques. Samples, which can be analyzed either as a liquid suspension or a dry dispersion, are passed through a laser beam, scattering the light. Detectors placed at fixed angles measure the intensity of light scattered at each position, and a mathematical model (Mie or Fraunhofer Theory) is then applied to generate a particle size distribution. The final result is reported on an Equivalent Spherical Diameter Volume basis.

Particle Size by Laser Diffraction is recognized by numerous standards and guidance agencies, including the ISO, ASTM, USP, EP and JP. This technique’s ability to perform dry or liquid dispersion analyses make it a good choice for general particle sizing applications, and its broad dynamic range (submicron to millimeters) has proven useful to industries including environmental, pharmaceutical, food, health, and beauty industries.

A wide variety of sample types can be analyzed by Laser Diffraction, including active pharmaceuticals (APIs), excipients, flyash, turbid wastewater, and environmental emission samples. Common applications include QA/QC batch testing, general survey screening measurements, and comparative studies.

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  • Widely used particle sizing distribution technique
  • Analyzed as liquid suspension or a dry suspension
  • Broad Dynamic Range; submicron to millimeters
  • Several laser diffractors onsite by multiple manufacturer to ensure best fit for material


  • Low resolution technique not a fit for analyzing low quantity outlier population
  • Not suitable for elongated or fiber-like material
  • Concentration dependent
  • Heterogenous material cannot be distinguished

Sample Requirements

Ideal sample amount is 5 to 10 grams for solid samples, especially for new material, to allow for the determination of adequate preparation and instrument settings.

For liquid samples, the preferred amount is 250 mL if the sample will be analyzed as received.

The above sample quantities are preferred. If sample availability is further limited, please contact us to share specifics about your sample and options for suitable sample quantities.

Detection Range

PTL’s Laser Diffraction Department can measure particulate from approximately 0.02 micrometers (um) up to 3500 micrometers (um) depending on the instrument model used. Detection range also varies with the dispersion method.  The wide analytical range allows for laser diffraction to be a popular option for general particle size determination.

Data Reported

While each data output may cosmetically look a little different, the general content of the reports is all the same. A comprehensive summary including the general graphical particle size distribution on a volume-weighted basis will be provided, as well as the most commonly requested parameters (10th, 50th and 90th percentiles, etc.). Information on specific sizes can be reported on request.


Particle Technology Labs has some of the top players in the industry, such as Malvern Panalytical, Beckman Coulter, and Sympatec to ensure we find the correct instrumentation for your material. This method has been used extensively in many industries including pharmaceutical, environmental, food, health, beauty and others. Sample material is passed through a laser beam resulting in the laser light scattered at a wide range of angles. Detectors measure the intensity of light scattered at that position. A mathematical model (Mie or Fraunhofer Theory) is applied to generate a particle size distribution. The final result is reported on an Equivalent Spherical Diameter Volume basis.

Malvern Panalytical Mastersizer 3000

Sympatec Helos

Beckman Coulter LS13 320

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