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Particle Scattering
The principle of particle scattering
When light passes through particles, scattering occurs. The intensity distribution, polarization, and spectral characteristics of the scattered light are all closely tied to the properties of the scattering object. By measuring the scattered light, it’s possible to gather a wealth of information about the structure and nature of the scatterer. Building on the principles of light scattering theory, technologies such as micro-particle measurement techniques, spectroscopy, rainbow refractometry, and phase Doppler technology have been developed. These methods find critical applications in micro-particle measurement systems—like particle size analyzers— Raman spectroscopy 、 Brillouin Scattering It has wide-ranging applications in fields such as multiphase flow and optical diagnostics of combustion processes.
Typical scatterers: biological cells, nanoparticles, and fuel particles
Principle and Components of Laser Particle Size Analyzers
The principle is that as the laser propagates, its wavefront becomes constrained by apertures or particles comparable in size to the wavelength. This constraint causes each elementary wave emanating from the restricted wavefront to interfere spatially, leading to diffraction and scattering. The spatial (angular) distribution of the diffracted and scattered light energy depends on both the wavelength of the light wave and the dimensions of the apertures or particles involved. Particle ensemble The diffraction, where the abundance of each particle size determines the intensity obtained at the corresponding specific angles. Light energy The size and the proportion of each specific angular light energy relative to the total light energy should reflect the abundance distribution of each particle size class. Following this approach, a characterization method can be established. Granularity level Abundance and the mathematical representation of light energy captured at each specific angular position Physics model , subsequently developing instruments to measure light energy. By comparing the light energy detected at a specific angle with the total light energy, it becomes possible to determine the abundance ratio of particles corresponding to each size class within the particle population. This process relies on the MIE scattering principle. Laser Particle Size Analyzer Assuming the particles being measured are perfectly spherical—making it impossible to assess their actual morphology—they are typically analyzed using offline particle size analyzers. These instruments can accurately determine particle size and distribution, covering a wide range of scales from millimeters down to sub-micron and even nanometer levels.
Laser particle size analyzers are categorized into wet testing instruments, dry testing instruments, and integrated dry-wet testing instruments based on their dispersion systems. Additionally, there are specialized models, such as spray-type laser particle size analyzers and online laser particle size analyzers, among others.
The main components of a laser particle size analyzer
1. Laser light source
Typically, lasers with good monochromaticity are used, Ultra-narrow linewidth single-frequency laser It's the top choice.
2. Optical System
Beam expander : Expand the laser beam into parallel light, ensuring a uniform spot on the sample.
Lens assembly: Includes a Fourier lens or focusing lens, designed to collect scattered light and project it onto the detector.
3. Sample Dispersion System
Wet dispersion: Achieves uniform distribution of particles in a liquid using a circulation pump, an ultrasonic disperser (to prevent particle agglomeration), and a sample cell.
Dry dispersion: Uses compressed air or a vibration device to disperse dry powders.
4. Scattered Light Detector
Annular or multi-ring array detectors (such as photodiode arrays) are used to capture scattered light signals from different angles.
Forward small-angle detectors (for measuring large particles) and side/backward detectors (for measuring small particles).
5. Signal Processing and Control Systems
The optical-to-electrical converter transforms light signals into electrical signals, which are then amplified and transmitted to the computer.
The software calculates the particle size distribution using algorithms such as Mie theory or the Fraunhofer diffraction model.
6. Data Processing Software
Displays the distribution of scattered light energy in real time and fits a particle size distribution curve (typically expressed as volume percentages).
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Principle of Laser Particle Size Analyzer |
Laser for laser particle size analyzer
Lasers used in laser particle size analyzers typically require high power stability (<0.3%), wavelength stability (<±0.1 nm), and ultra-low noise levels (<0.1% over 4 hours). . Regarding performance Repeatability and beam quality (TEM) 00 ) Also has very high requirements, while also demanding strong environmental adaptability and robust structural integrity. Compact Stability with Ensure long-term Hot Stability and mechanical stability , the shorter the wavelength, the higher the measurement accuracy. Commonly used is Narrow-line-width and single-frequency lasers , wavelengths include 405 nm, 532 nm, 633 nm (which can replace the helium-neon laser), as well as 671 nm, 780 nm, 830 nm, and more.
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Fiber-coupled output laser | Low-noise, High-Stability Single-Frequency Laser |
Changchun New Industries Optoelectronics Technology Co., Ltd.
Address: No. 888 Jinhu Road, High-Tech Zone, Changchun, 130103, P.R.China
International Tel:+86-431-85603799
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