Fabrication of holographic diffractive optical elements for enhancing light collection from fluorescence-based biochips

An approach to enhancing the light collection from fluorescence emitters bound on the surface of a biochip is presented. It is based on the integration of diffractive optical elements on the underside of the chip that are essentially thick volume holograms written into a layer of photopolymer recording material. The high diffractive efficiency and angular selectivity of these types of diffractive elements make them very effective collectors of the spatially anisotropic light emitted by surface-bound fluorophores. The holographic lithography setup used to fabricate the diffractive elements is described. Results obtained using both a focused laser and light from a fluorescence spot to characterize the performance of the diffractive optical elements are presented.