Polymeric graded-index preforms

Polymeric graded-index preforms were produced in an ultracentrifuge in two steps. In the first step, the cladding monomer (tetrafluoropropyl methacrylate) is polymd. in a drum/vessel which is rotated horizontally at 5000 rpm. The resulting tube is subsequently filled with the core monomer (Me methacrylate) and rotated vertically at high velocities (>10000 rpm) around its center axis. A concn. gradient in radial direction is generated and fixated by homopolymn. of the core monomer in the ultracentrifuge at elevated temp. Interference microscopy and Raman spectroscopy measurements show that parabolic-like refractive index profiles can be obtained i.e. the described process provides graded-index preforms for the prodn. of graded-index optical fibers and lenses. Upon injecting a laser into the graded-index preforms, the expected light trajectory is obsd. indicating that the proper lens characteristics are obtained. One of the potential advantages of the process is that large diam. preforms can be produce