Laser particle size analyzerIt is based on the principle of particle scattering of light, that is, the interaction between light and particles, and the scattering law of particles on incident light (Mie scattering theory) to achieve particle size testing. In ordinary physics, light propagates in a straight line in a pure transparent medium, but when there are particles, droplets, or bubbles in the medium, the light beam will change its original propagation direction and scatter in all directions.

When a beam of parallel light shines on a screen with small holes, Airy spots will be generated behind the holes, and the distribution of Airy spots is closely related to the size of the holes. The bright rings of Airy spots generated by larger holes are close to the center, while the bright rings of Airy spots generated by smaller holes are far away from the center (Δ θ=1.22 λ/d). This is the theory of small hole diffraction - the Fraunhofer diffraction theory.

According to the Babkney principle, particles, droplets, or bubbles in the optical path are like small holes, which conforms to the Fraunhofer diffraction theory. However, the Fraunhofer diffraction theory is only an approximate solution of Mie scattering theory when the particle size is much larger than the wavelength of the incident light (d>>λ), while Mie theory is a strict mathematical solution to the boundary conditions of the Maxwell equation for an isotropic single medium sphere in a homogeneous medium under monochromatic parallel light irradiation. With the advancement of technology,Laser Particle Size AnalyzerWhether to adopt Mie scattering theory has become a sign. The HYL series laser particle size analyzer is developed based on Mie scattering theory.