Study the Effect of Concentration on the Evolution of Far-Field Diffraction Patterns of Bromocresol Purple and Congo Red Solution

Abstract

Experimental evolution of the diffraction pattern of Bromocresol Purple (BCP) and Congo Red (COGR) Solutions, by diffraction ring technique under CW laser illumination is present. The two azo dyes, COGR dye and COGR dye, were studied for their absorbance spectra, as well as the diffraction rings experimental. The measurement rings were performed when the incident beam propagates through a quartz cell containing dye. Many diffraction rings were observed on the sensitive screen. Among the results we obtained are the diffraction rings at 0.07mM concentration, where the number of rings was 4 at the power of the 50 mW laser beam for the Bromocresol dye and three rings in the congo red dye. The nonlinear refractive index for the Bromocresol dye and congo red dye are found to be in the order of 0.11×10−8 cm2/Watt, 3.093×10−8 cm2/Watt, respectively.The efficiency of the ring pattern was found to depend on the concentration of the dye and the power of the laser.