apparatus and method for forming an integral structure , such as a lens , on a fiber , such as an optical fiber , which includes a device which imparts centrifugal force to an end of the fiber while the end of the fiber is being heated . an arc or heat source which heats the end of the fiber can both rotate about the longitudinal axis of the fiber and move laterally with respect to the longitudinal axis of the fiber . the apparatus also includes a device for longitudinally moving the fiber relative to the arc . when a fiber is inserted into the apparatus , centrifugal force is exerted on the end of the fiber as the fiber is heated . the fiber is advanced longitudinally relative to the arc until a sphere of a predetermined size is formed . then , depending upon the shape or lens desired , the sphere may be allowed to cool and be removed from the apparatus , or other operations are performed .