The ability of an optical security device to provide a highly attractive overt image yet contain variable behaviour, so end-users can easily authenticate, is why secure optical technology remains prevalent. Even as digital and electronic security becomes more dominant, optical security for on-product and physical items remains key. Over time the technology has evolved to allow for absolute control of optical structure shapes using laser and Ebeam lithography. This combined with advanced optical modelling, used to predict behaviours, has enabled a plethora of novel effects from micro reflective, diffractive, and sub-wavelength scale devices, which were simply not feasible a few years ago. Diffraction and reflection have been augmented using plasmonics and sub-wavelength interactions widening the available toolkit of optical phenomena. Furthermore, state of the art equipment now allows these structures to be originated together, further enhancing security and creating significant new barriers to counterfeiters. Mass production of such nano and microstructures is still effective and commercially viable, this is enhanced by advances in on web laser processing to embed unique identifiers within such state-of-the-art OVDs rather than printing on a fixed image which is easier to replicate. These unique OVDs can then interact effectively with mobile authentication for item level traceability, making unique in production OVDs a reality.