There are two methods of operation described in the literature . In one, the fringe orders were used, and in the other one, the separation distances of the maximas were used of the profile. A helium-neon laser was used and was passed through a density filter to avoid the phenomena of saturation of the CCD camera. The beam was first split using a beam splitter, and one of the beams passed through the diffusion cell. Both the beams were then recombined using a second beam splitter. A lens was used to project the image of the cell on a screen on which the camera was focused. Interference images of both methods have been provided below. The images obtained were digitally subtracted from each other using image processing software, and the diffusion coefficient was related using Fick's laws .