1838. That was the year when, according to a fascinating AR/VR infographic from HistoryDegree.net and reposted to Techrepublic.com, AR got started. In 1838, Charles Wheatstone, a professor of experimental philosophy, invented the stereoscope, a device for viewing images in 3D. Since then, there has been a range of ocular devices for education, entertainment, and business — the kinetoscope, flight simulators, the View-Master, the Telesphere Mask, NASA’s Virtual Interface Environment Workstation, and the Sword of Damocles — to name a few. For those not entirely clear on the differences, AR layers graphics or information, via a smartphone or spectacles, on top of one’s physical world. Head-up displays (HUDs) are visual overlays that project digital data on a screen or windshield; for example, to a pilot or driver. Mixed reality (MR) creates spaces that merge computer processing with input from human and physical worlds. And VR is a completely immersive experience that blocks out one’s physical surroundings. Those who work with each type of reality are aiming to not only improve user experience, but to meet a range of needs across commercial, industrial, corporate, medical, entertainment, or consumer markets. This translates into a tremendous amount of innovation, conversation, attention, investment, and curiosity in this space now. Recently, I came across a video of a man who experimented with living inside a VR headset for 168 hours — an entire week. Admittedly, it was hard to watch. While he seemed very glad at the end to emerge and get back to the natural world, he provided some interesting commentary throughout the experience: “Float above the Earth. Watch a Space X launch. Everything you do will be tracked. Time is a concept. The sun cannot be seen. You can find your digital tribe. VR menus will infiltrate your dreams. It is a new medium for human experience. Anyone can make their own environment. Everything is in the headset.” Based on the number of views — 16 million in a month! — he may be right: Everything is in the headset. To learn about holographic combiners and recent developments in optics for AR and HUDs, read Pierre-Alexandre Blanche’s feature. And, to find out more about the role of freeform and nontraditional optics in AR/VR, have a look at Farooq Ahmed’s article. Enjoy additional articles on characterizing quantum dots, multidimensional coherent spectroscopy, optical coatings, and imaging for quantum materials research. Warmly,