![]() This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Analytics". The cookies is used to store the user consent for the cookies in the category "Advertisement". These cookies do not store any personal information. This category only includes cookies that ensures basic functionalities and security features of the website. Necessary cookies are absolutely essential for the website to function properly. The following figure shows an example of a volume-related particle size distribution of a calcium carbonate powder – measured with a Bettersizer S3 Plus. This theory is applicable for particles of all sizes. The knowledge of the complex refractive index of the particles and the liquid as well is necessary. In contrast, the Mie theory uses the hypothesis of virtually translucent and spherical particles, meaning that the light permeates the matter and is scattered elastically at the atoms of the particle. However, this theory is only suitable for mean particle sizes from approx. Therefore no additional optical input constants of the material are necessary for this calculation. The Fraunhofer theory is based on the hypothesis of opaque and spherical particles: the scattered pattern corresponds to a thin opaque two-dimensional plate – diffraction only occurs at the edges. To calculate the particle size distribution from the measured scattering spectra, the theory of either Fraunhofer or Mie is applied. Therefore, neither the suitable lenses for the corresponding particle size measurement range have to be selected prior to the measurement (in comparison to the Fourier optics), nor do measurement inaccuracies result from different particle to detector distances, if not all particles lie in one plane (in comparison to the inverse Fourier optics). Thanks to DLOIOS technology, the problems of conventional measurement setups can also be avoided. This offers the advantage that the scattered light can also be detected at very large angles (in backward scattering direction) and thus even very small particles can be measured precisely. The particles will interact with the light within a parallel laser beam. This is achieved by means of a so-called double lens design and oblique incidence optical system ( DLOIOS technology): Fourier lenses (collective lens) are positioned between the laser and particles as well as between particles and detectors. in forward, side and backward direction. ![]() State-of-the-art laser diffraction systems such as the Bettersizer S3 Plus guarantee the determination of scattering intensities in a continuous angular range of 0.02 – 165°, i. The scattering intensity is determined by stationary detectors depending on the angle (light scattering intensity distribution). ![]() State-of-the-art laser diffraction devices such as the Bettersizer S3 Plus solve these tasks by an innovative design of the optical bench for the detection of backscattered light of very small particles and by detecting large particles by an integrated high-speed CCD camera or the combination of static light scattering and dynamic image analysis. Particularly the precise and reproducible detection of particles with sizes close to the measuring range limits as well as the simultaneous determination of particle sizes of very small particles (nanometer range) as well as large particles (lower millimeter range) for the characterization of polymodally or very broadly distributed samples provides a challenge. The range of applications is increasing permanently and hence the requirements on the measurement methods regarding size range, measuring time and reproducibility. Examples are construction material (sands, cements), lime stones, ceramics, colored pigments, fertilizers, emulsions and may more. The particle size distribution as a parameter to specify a powder or dispersion plays a central role in many applications. Particle size measurement using static light scattering
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