Diffractive optical elements: A novel concept for automotive lighting.

Recent developments in automotive lighting are heading towards the use of laser based front and rear lights. While numerous work has been done for laser based front lights, less attention has been paid towards rear and brake lights. We present a simple and cost effective method to design and fabricate diffractive optical elements (DOEs) for projection of desired intensity distributions. The DOEs, i.e. a combination of several diffraction gratings, each of these gratings computed in MATLAB contribute to the desired pattern. The computed gratings are patterned onto the photoresist coated on silicon wafer to prepare stamps using a maskless lithography optical setup employing a digital mirror device and spatial light modulator for 2D and 3D structures, respectively. In the next step, PDMS (Polydimethylsiloxane) is coated onto the microstructured surfaces of silicon substrates to prepare soft stamps and then transfer the DOEs onto the PMMA (Polymethylmethacrylat) by hot embossing. The DOEs are characterized in terms of surface profile and diffraction efficiency. In future, this work will contribute to the production of cost effective DOEs for automotive lighting.