You may know them best for their original use in lighthouses, where they're famously recognised as "the invention that saved a million ships". Or perhaps you initially think of their employment in traffic light design, where they're used for the same inherent advantages. But, in recent years, Fresnel Lenses, and their unique characteristics, have been recognised and tapped into by a different sector – the virtual reality (VR) industry. Here, Knight Optical, a leading supplier of optical components and a trusted supplier of stock and custom-made Fresnel Lenses, looks back at the history of the optic, probes into its home in the world of VR and head-mounted displays (HMDs) and explores other sectors that employ its use. Let's begin with the basics: What Are Fresnel Lenses? As mentioned, Fresnel Lenses were initially intended for use in lighthouses. Their popularisation is thanks to French Physicist Augustin-Jean Fresnel, from whom the optic gets