Air particle counter is an instrument used to detect the quantity and particle size distribution of particles in the air, widely used in clean room environmental monitoring, air quality detection, pharmaceuticals, semiconductor manufacturing, food production and other fields. Its main function is to collect air samples, measure the concentration and particle size of suspended particles in the air, and evaluate the cleanliness of the air.

1、 Working principle

　　airborne particle counterThe working principle mainly includes three steps: particle collection, particle detection, and data processing. Its core technology usually relies on the principles of light scattering, laser scattering, optical sensors, etc.

1. Particle collection

Firstly, air is drawn into the instrument through a fan, and larger particles are removed through a specialized filtration system to ensure that only tiny particles suspended in the air are detected. The detection range of these particles varies depending on the equipment used.

2. Particle detection

After entering the detection area, particles usually pass through an area illuminated by a laser or light source. Using optical sensors or laser beams to irradiate particles in the air, detecting the presence and size of particles by utilizing scattered light signals generated by the interaction between particles and light sources. The intensity of scattered light is directly proportional to the size and number of particles. By measuring the intensity and variation of scattered light, the size and concentration of particles can be identified. Particles of different sizes will produce varying levels of scattered light intensity, allowing for the estimation of particle size based on the strength of the scattered light.

3. Data processing

After the scattered signals of particles are collected, they enter the data processing system and are processed based on the intensity and time of the scattered signals, ultimately calculating the number of particles in different particle size ranges in the air. The results are usually expressed in terms of the number of particles per cubic meter, and particles of different sizes are counted separately to form a particle size distribution curve, reflecting the overall condition of air quality.

2、 Precision analysis

Accuracy is an important indicator for evaluating the performance of air particle counters, which directly affects the reliability of measurement results. The accuracy is mainly affected by the following aspects:

1. Accuracy of particle counting

Its accuracy depends on the sensitivity and resolution of the particle detection system. The higher the sensitivity, the smaller particles can be detected; The higher the resolution, the more accurately particles of different sizes can be distinguished. Usually, particles larger than 0.1 microns can be detected, but for smaller particles, measurement errors may increase, resulting in poor counting accuracy for ultrafine particles.

2. The influence of optical systems

Optical systems, such as lasers, light sources, detectors, etc., have a significant impact on measurement accuracy. The measurement accuracy of laser scattering method is related to the wavelength of the light source, the sensitivity of the detector, and the angle distribution. The stability of the light source, calibration of the detector, and noise level of the system can all affect the accuracy of particle detection. The higher the resolution of the optical system, the more accurate the instrument can count smaller particles.

3. The shape and refractive index of particles

It is generally assumed that particles are spherical, but in reality, particles in the air may have irregular shapes, which can result in different patterns of light scattering from spherical particles, thereby affecting the accuracy of measurements. In addition, particles of different materials have different refractive indices, and particles with higher refractive indices may scatter stronger light signals, leading to their misjudgment as larger particles. Therefore, the shape and refractive index of particles can also affect accuracy.

The air particle counter is an important tool for evaluating air quality, monitoring clean room environments, and detecting air pollution in industrial production. Its working principle relies on light scattering technology, which determines the number and size of particles by detecting the scattering intensity of light by particles. Accuracy analysis shows that its accuracy is influenced by various factors, including the design of the optical system, airflow velocity, particle morphology, and environmental conditions.