Laser diffraction is the established and most efficient light scattering method for particle size analysis covering a wide range from submicron to millimetre scale. In the early 1980s, Sympatec introduced a breakthrough innovation which was leading laser diffraction to another dimension: dry powder dispersion for even the finest, cohesive powders came true with RODOS. And with the R series of our laser diffraction sensor HELOS new benchmarks for precision and accuracy have been achieved. Latest improvements comprise enhanced application of parameter-free Fraunhofer evaluation down to the submicron regime (below 1 µm), the greatest measuring signal frequency for best resolution with range combination technology and more powerful evaluation modes (Fraunhofer & Mie). Laser diffraction is now even closer to absolute standards. Continually, industrial requirements and limits are considerably outmatched.
Our solution with HELOS and MYTOS
Within our laser diffraction systems the primary physical diffraction set-up is realised deploying a parallel laser beam. This yields the purest optical alignment for analysis of extended special arrangements of particle collectives which allows for size characterization beyond limiting assumptions and constraint.
Following the premise of Fraunhofer diffraction scattered light of absorbing particles is measured under low angles in forward direction only. In contrast to Mie theory only the Fraunhofer model does not require knowledge of optical properties. Hence, solely Fraunhofer is applicable to mixtures of different materials and shapes. With laser diffraction the determined particle size always refers to the equivalent diameter of a sphere sharing the same diffraction pattern.
Within the past twenty years laser diffraction has become the dominating technique in particle sizing. In earlier days off-line particle size analysers have been adapted by sampler couplers to process pipes. Today you will also find the MYTOS family with in-line, on-line and at-line laser diffraction systems in our instruments portfolio especially adapted to the process.