To investigate the influence of a single vortex ring to turbulence, Laser Rayleigh scattering(LRS) method was setup. LRS method, which is able to measure the mole fraction in a flow field, was used to show the diffusion condition of the fluid mechanics. A certification on the possible adaptation of LRS method to the single vortex ring was carried out in the turbulent circular jet using point measuring technique by Ar-Ion laser with PMT and 2-dimensional measuring technique by Nd:Yag laser with ICCD of LRS method. A calculation or image processing was performed for the data of mole fraction from the scattering signal or the scattering image. Images of the single vortex ring were obtained by 2-D LRS method. Dimensionless parameters are used to explain the circulation of single vortex ring. When the vortex rolls up, in case of Mie scattering image, the fuel and air seemed to rotate by layered feature but in case of LRS image, the layered feature was not appeared but the mixture of the fuel and air was observed. When the diffusion condition is needed to explain, the LRS method is compatible, not the Mie scattering method using particles.
