Application of Semiconductor Lasers in PM2.5 Dust Sensing Technology

Dust detection technology was first born in the 1950s, with the developed countries represented by the UK, US, Japan and Germany taking the lead in relevant research and applying it to industrial and mining dust monitoring and other scenarios for controlling and preventing various occupational diseases caused by respirable dust. After decades of development, dust detection technology with light scattering principle as the core has also gradually entered the civil field such as air purifiers. since the 21st century, with the acceleration of China's industrialization process, the environmental pollution problem as a by-product has also become increasingly prominent, and the respiratory health of urban residents has been affected by the haze problem, so the "PM2.5 " as the representative of the particulate matter pollution detection technology also entered the public eye for the first time, becoming a key topic of widespread social concern, PM2.5 sensors have also gradually become an important tool for indoor, car and public places air quality detection.
Early dust sensors, mainly using infrared LEDs as the light source, generate heat through resistance to obtain hot air flow. When there are particles in the air through, scattering occurs after contacting the LED light source, which is received by the photosensitive detector to generate electrical signals of different sizes, and the detection results are obtained after amplification and arithmetic. In this technology, due to the low intensity of LED scattered light, heating resistance to produce a weak airflow, usually only effective for larger particles greater than 1μm in diameter, and only through the duty cycle of the electrical signal to characterize the change of particulate matter in the air, the measurement value error is larger, and can not adapt to the dust source changes in the environment, it is difficult to achieve real-time monitoring of PM2.5 and other particulate matter.
Dust detection technology was first born in the 1950s, with the United Kingdom, the United States, Japan, Germany as the representative of the developed countries to take the lead in relevant research, and its application in industrial and mining dust monitoring and other scenarios, for the control and prevention of various occupational diseases caused by respirable dust. After decades of development, dust detection technology with light scattering principle as the core has also gradually entered the civil field such as air purifiers. since the 21st century, with the acceleration of China's industrialization process, the environmental pollution problem as a by-product has also become increasingly prominent, and the respiratory health of urban residents has been affected by the haze problem, so the "PM2.5 " as the representative of the particulate matter pollution detection technology also entered the public eye for the first time, becoming a key topic of widespread social concern, PM2.5 sensors have also gradually become an important tool for indoor, car and public places air quality detection.
Early dust sensors, mainly using infrared LEDs as the light source, generate heat through resistance to obtain hot air flow. When there are particles in the air through, scattering occurs after contacting the LED light source, which is received by the photosensitive detector to generate electrical signals of different sizes, and the detection results are obtained after amplification and arithmetic. In this technology, due to the low intensity of LED scattered light, heating resistance to produce a weak airflow, usually only effective for larger particles greater than 1μm in diameter, and only through the duty cycle of the electrical signal to characterize the change of particulate matter in the air, the measurement value error is larger, and can not adapt to the dust source changes in the environment, it is difficult to achieve real-time monitoring of PM2.5 and other particulate matter.
In addition to indoor appliances, the demand for PM2.5 detection in cars and outdoor environments is also growing. In the face of more complex environments, the low-power semiconductor laser used in the sensor is required to have a stable light power, and can also work for a long time in a wide range of ambient temperature changes, so the overall reliability of the laser has put forward higher requirements. Early PM2.5 sensors mostly use imported brands, but in recent years many domestic companies have made key technological breakthroughs in the development of semiconductor lasers, the high reliability of epitaxial structure design and growth, high quality cavity surface coating process, automatic gold-tin eutectic process, automatic aging and test staging and other advanced technologies into the field of small power semiconductor laser manufacturing, to 650nm, 790nm as the representative of the small power semiconductor laser products, can be used in the field of laser manufacturing. The small power semiconductor laser products, represented by 650nm and 790nm, can work stably under the harsh environment from -40℃ to 85℃, and have been recognized by leading companies and many customers in the field of PM2.5 detection, and have been used in indoor and outdoor and vehicle PM2.5 sensors on a large scale for many years.