Method of Aerosol Absorption Detection with Photothermal Interferometry

AbstractThe photothermal interferometry method with higher accuracy and lower uncertainty can directly measure the absorption coefficient of atmospheric aerosols and be unaffected by scattered light. With Jones matrix expression, the math expression of a special polarization interferometer is described. This paper using folded Jamin interferometer, which overcomes the influence of vibration on measuring system. Interference come from light polarization beam with two orthogonal and then combine to one beam, finally aerosol absorption induced refractive index changes can be gotten with four beam of phase orthogonal light. These kinds of styles really improve the stability of system and resolution of the system. Four-channel detections interact with interference fringes, to reduce the light intensity ‘zero drift’ effect on the system. In the laboratory, this device can be sensitivity to the refractive index of air, which have close relation with aerosol absorption index; it shows that the result principally agrees with actual value. This kind of instrument will be used to monitor ambient aerosol absorption and also be sensible for chemical component of suspended particulate matter