Diffraction phenomenon of light can beobserved when a laser beam passes through a diffraction slit. The intensitypattern can be determined using a pin photo detector with fine movement acrossthe diffraction pattern. In the present setup, the light intensity in the termsof current or voltage is noted at closed intervals by finely traversing thedetector movement and observing the light intensity on a digital multimeter.The intensity versus distance curve is plotted on a graph for calculations. Thedevice consists of one meter long optical bench with two transverse saddle forlaser and slit mount and one transverse saddle with micrometer for detector. Anumber of diffraction slits and gratings are provided with this setup.