How does a dust particle counter work?

How does a dust particle counter work? Dust particle counters are widely used in clean room testing in industries such as biopharmaceuticals, microelectronics manufacturing, laboratories, and microbiology. They can monitor the cleanliness and purification effect of clean rooms, dust-free workshops, and processing and manufacturing plants, ensuring the safety and quality of products. Below are some knowledge about dust particle counters.

1、 Working principle of dust particle counter
Particles in the air will scatter under the illumination of light, which is called light scattering. Light scattering is related to factors such as the volume of particles, the length of light waves, the refractive index of particles, and the absorption characteristics of particles towards light. The intensity of scattered light from particles increases with the surface area of the particles. The working principle of the dust particle counter is to focus the light from the light source into the measurement chamber through a lens group. When each particle in the air quickly passes through the measurement chamber, it scatters the incident light once, forming a light pulse signal. This optical signal is sent to the photodetector through a lens group, which is proportionally converted into an electrical pulse signal. After amplification and discrimination by the instrument's electronic circuit, the required signal is picked out and displayed through a counting system.
2、 Workflow of Dust Particle Counter
Firstly, the vacuum pump system in the cleanroom allows the gas to be detected to pass through the particle counter laser head at a specified flow rate. The dust particles in the gas scatter the laser signal in the particle counter, causing the optical sensor to receive and generate a pulse information signal. Then, the pulse signal is output and amplified, converted into a digital signal for processing, and compared with the particle signal to represent the comparison results with different parameters. The number of electrical pulses corresponds to the number of particles, and the amplitude of electrical pulses corresponds to the size of particles.