Interpretation of the operating principle of the laser particle sizer

The working principle of the laser particle size analyzer is based on the theory of light scattering and the theory of diffraction.

When the beam of light is projected onto the dispersion system of the instrument, absorption, reflection, scattering and diffraction of light may occur.

When the frequency of incident light is the same as the natural frequency of the molecule, absorption of light occurs;

When the length wavelength of incident light light is smaller than the size of the scattered particles When the wavelength of the incident light is larger than the size of the particles of the dispersed phase, light scattering occurs.

Generally, for particles smaller than 0.1μm, the diffraction phenomenon disappears, and the scattering phenomenon mainly occurs;

Particles of 0.1 to 10 μm are mainly diffracted light. The particles will produce partial refraction and scattered light; for particles larger than 10 μm, scattering and refraction will disappear, and diffraction will dominate.

According to Fraunhofer\'s diffraction theory, for particles of 10μm, 0.1~10μm, the size of the diffraction angle is related to the particle size, and the intensity of the diffracted light is related to the number of particles. Determine the size and number of particles.

For particles smaller than 0.1 μm and 0.1-10 μm, according to Mie scattering theory, not only light diffraction, but also scattering and the refraction of light are taken into account, and according to the complete refractive index of the particles, the Calculate to find the size and size of the particles.

Tag: laser particle sizer