In summary, innovations in excitation light resources have transformed fluorescence imaging and enabled new insights in to cellular and molecular procedures. These types of techniques have improved spatial resolution and reduced phototoxicity, enabling deeper imaging of living organisms. As new technologies continue to emerge, fluorescence imaging will probably remain at forefront of biological and medical search.Single molecule imaging is a powerful technique it allows researchers towards visualize plus learn their behavior of individual molecules as part of complex biological systems. One critical component of the method is the excitation light source, which is used to stimulate fluorescence in target molecule. In recent years, advances in this technology have opened upwards new possibilities for one molecule imaging, enabling researchers to imagine as well as study complex biological