PM2 5 using laser diodes

5 sensor operates on the principle of light scattering. It consists of a LASER diode, a photodiode, a microcontroller, a low-noise amplifier and a suction fan. As air is drawn into this chamber, either by a small fan or through natural convection. Using laser scattering principle: Light scattering can be induced when particles go through the detecting area. The scattered light is transformed into electrical signals and these signals will be amplified and processed. [pdf]