Principle of operation The QT-1 laser particle size analyzer uses Mie scattering theory to measure particle size, considering the refractive index of the particles and dispersion medium. According to Mies theory, a particle will scatter light at an angle determined by that particles size. A collection of particles will produce a pattern of scattered light defined by intensity and angle that can be transformed into a particle size distribution result. The data of particle test can be calculated in two ways: unconstrained fitting inversion and constrained fitting inversion. The constrained fitting inversion is a relatively simple way. The particle size distribution is inverted with the assumption that there is a certain distribution pattern in particles. However, the deviation exists between the assumption and the reality. Therefore, the tested results through the constrained fitting inversion cannot truly reflect the real size distribution of the particles. In unconstrained fitting inversion, no distribution pattern of particles is assumed before the test, and the size distribution of the particles is directly and precisely calculated from the light intensity. In this way, the instrument requires reasonable sensor design and size grading to ensure its high performance. The particle size distribution can be precisely calculated with QT-1 Laser particle size analyzer which uses the optimized non-uniform cross 3D fan-shaped sensor array and the reasonable size grading.
