Production of polymer diffractive optical elements by contact printing

We present the fabrication of phase only diffractive optical elements (DOEs) by contact prints using a novel technique. Phase only DOEs consist of a transparent slide with a surface profile that modulates the phase of an incident laser beam in the desired manner. This surface profile can be exploited to split or to shape the laser beam. In our process a Perspex sheet (PMMA) is exposed through a chrome-on-quartz mask that carries the DOE pattern. The UV light used in the exposure is generated by an ArF excimer laser (λ=193nm). The high energy radiation causes photomodification and the phase pattern of the DOE is transferred to the PMMA. While the primary investigations concentrate on binary DOEs, which require one exposure only, we have also attempted to produce multilevel designs which need mask alignment and tighter control of the exposure. At the moment, we study the capability of the method to produce relatively large structures but it might also be possible to use it to manufacture finer structures.