Focusing properties of microspheres containing multiconcentric metallic rings

摘要

We fabricated multiconcentric metallic rings on a polystyrene microbead by using a focused ion beam. We found this type of structure possesses good focusing properties unlike planar multiconcentric metallic rings, which require varying the width of each ring. In addition, we found that we can change the shape of the bead by heating it, after which we then fabricated multiconcentric metallic rings around it. Our results showed that the focal distance of the structure as well as the size of the focal spot increased as the heating time increased. These kinds of structures have good potential for application to optical imaging and photolithography.