In this paper, we observed optical responses of Erioglaucine (acid blue 9) with several techniques in different concentrations. Experimental Setups are similar to standard z-scan: close and open setups were employed to determine the nonlinear refraction and nonlinear absorption coefficients, respectively. It is interesting during the experiments, every concentration has various behaviors. As the phase shift in some concentrations is greater than pi, then z-can equations are not valid: therefore, we indicated the nonlinear responses by beam radius variations for pi < vertical bar Delta phi(0)vertical bar < 2 pi, and then compared some numerical Calculations and diffraction patterns observed in far-field for vertical bar Delta phi(0)vertical bar >= 2 pi. (C) 2008 Elsevier B.V. All rights reserved.