Various kinds of optical diagnosis for atmospheric pressure non-thermal plasma which the authors have examined experimentally, are explained. They are LIF of OH (248nm excitation), NO (226nm), TARIF of O (225nm), Sclieren image, ozone profile observation by the laser absorption, spectrum analysis of the plasma including NO-γ emission, and streamer propagation. The last can be controlled by the gated IICCD camera but others are controlled by the laser emission which makes possible to observe the time change after the plasma. Those data propose the O generation in the streamer region which produces the ozone or VOCs oxidation. O radical is now a very important parameter as the VOCs decomposition, especially, related with the catalyst effect.
As a diagnosis tool of the atmospheric pressure non-thermal plasma, some Laser-Induced Fluorescence (LIF) techniques are described. The observed radicals are OH and NO in the plasma region generated by the electric pulse discharge or DC corona. Time variations of 2 dimensional distribution of OH or NO were observed just after the pulse excitation. Precise OH or NO concentration changes with time were also recorded related with some contamination and other parameters. Ground-state OH density is maximum at 30 or 50 microseconds after the submicrosecond pulse discharge in arc mode but the OH density is largest just after the pulse discharge if the plasma is the non-thermal plasma. NO decomposition occurs just in the streamer, and decomposing area increases from that streamer area with time, if NO concentration is low.