PREEXPOSURE FOR 2D GRATINGS IN PHOTORESIST

The applications and fabrication of two dimensional holographic gratin gs, recorded perpendicularly into UV-active positive photoresist are d iscussed. A new photoresist mixture with which it is easy to control t he coating layer thickness is presented and characterised. Three diffe rent exposure processes including sequential nonholographic and hologr aphic stages which allow greater control of the mediums response and t hreshold are investigated.