In order to reduce and prevent effects of haze weather on people’s life and health

haze detecting equipment is studied

propose a design of PM 2.5 detecting sensor.This design according to principle of photoelectric sensor

uses correlation type detection way use semiconductor laser

with wavelength of 650 nm

power of 10 mW as light source

use avalanche photodiode with the gain

good sensitivity as receiver.After the processing of conditioning circuit that is composed by the I / V conversion

voltage amplifier and voltage follower which has low bias voltage

low temperature drift and high performance voltage follower

to complete design of particle detecting sensor.Experimental results show that the sensor is accurate

fast response

small error and provide a hardware foundation for accurately measure concentration of particulate matter.