Heads up! Novel Technology Redefining Holographic Windshield Displays

A German-Scottish-US partnership has jointly developed technology that advances holographic transparent displays on vehicle windshields.

Head-up displays, known as HUDs, project useful information such as speed, safety alerts and turn-by-turn directions on the lower part of the windshield, where drivers can see it without taking their eyes off the road. The information can be projected transparently on the glass, allowing a clear line of sight beyond the information being displayed.

“We have been working closely with global OEMs for years and are now at a tipping point for adoption and scaling of this display technology,” said Andy Travers, CEO of Livingston, Scotland-based Ceres Holographics. “This is being driven by a combination of a desire for more safety-oriented and intuitive information display features, pressure from safety regulators to reduce driver distractions, and the accelerated pace of innovation and associated need for differentiation among a new generation of car makers.”

Ceres collaborated with Kingsport, Tenn.-based Eastman Chemical Co., benefiting from the firm’s Saflex-brand interlayer solutions and encapsulation know-how, together with Leverkusen, Germany-based materials giant Covestro AG. The parties combined Covestro’s expertise in photopolymer films, Ceres’ digital mastering and HoloFlekt^® roll-to-roll replication system, which produces finished films up to 1,200 mm wide, and Eastman’s technique to encapsulate functional films into automotive-approved laminates.

They found a way to incorporate multiple custom-designed holographic optical elements (HOEs) into a single sheet of Covestro’s Bayfol HX® film, which is then laminated with Eastman’s newly developed interlayer stack, to achieve the industry's largest field of view HUD.

Günther Walze, Covestro’s head of holographic lightguiding, said the photopolymeric coating can be tailored with varying properties and thicknesses and applied on different flexible substrates, depending on the customer’s specification. “And in this coating you can write and record optical functions, and that is the key to all those applications we were talking about.”

The partners have signed a memorandum of understanding (MOU) to explore commercial production of the cutting-edge Holographic In-Plane Transparent Display (HIPTD) product. That, they explained, is a laminated hologram solution that allows multiple head-up transparent displays in a single fully laminated windshield, with each display area measuring up to 400 by 300 mm.

In a joint statement, the firms said the MOU builds on years of collaboration, leveraging each company’s technologies to manufacture holographic-enabled transparent HUDs for the automotive market. It enables them “to look into the remaining steps needed to set up and establish the required facilities and manufacturing capacity, ensuring an efficient, market-ready supply chain to meet the planned production timelines of OEMs wishing to adopt the technology for new driver and passenger experiences.”

In doing so, the partnership aims to accelerate the commercialization of the HUD solution, with Eastman leveraging its relationships with automotive OEMs and Tier One automotive glazing suppliers.

A development team from Ford Motor Co. presented the results of their evaluation of the Ceres/Eastman/Covestro solution at an industry conference in the Fall of 2024.

Ceres Engineering Director Dr. Andrew Grant explained in an interview that his firm can program “about a million holographic pixels per A4-sized area, and every pixel is programmed to send the light from the projector back toward your eyes, and only toward your eyes.”

Does it raise distracted driving concerns? Grant contends it is just the opposite. The technology enables bringing information up from, say, the cluster or from a center stack, and displays it transparently on the windscreen below  the driver’s line of vision. So this actually helps to minimize distractions, he claims. And because each display can only been seen by the intended viewer, it allows personalized experiences for drivers and passengers, further reducing distractions brought on by “look down’ shared center console displays.

Walze said, “Our Bayfol® HX photopolymer enables next-generation, truly transparent projection displays for windshields while meeting the high automotive safety requirements. With the necessary establishment of hologram mastering and scalable mass-production replication equipment by Ceres, combined with Eastman’s windshield lamination technology, this innovation is ready for deployment to end customers.”

This photopolymer film is commercially available, he notes, while acknowledging it is not yet being used in commercial applications for vehicle windshields. Automakers have long development and approval timelines, so he expects the technology for that application to launch in a vehicle in 2027 or 2028.

“Actually,” Walze explained in an interview, “we're not necessarily trying to replace a standard head-up display. This is sometimes a misconception, which is easy to make, because we bring a display in the windshield. But the main idea is to find another place for all the screens that are in the dashboard now with the new cars.”

Many new car models have a screen for the driver, a second screen in the middle, and a third screen for the passenger. “All those screens in the dashboard can be moved to the bottom or the sides of the windshield, and that is the main target application,” Walze said. “So you can also argue that by moving all those screens in the windshield, there is also an overall cost-saving potential.”

This technology offers flexibility, says Grant. “You can use the same technology in a whole range of cars. We've done it for heavy-goods vehicles, 18-wheelers. We've done it tractors, trains, that sort of stuff.”

Ceres takes the design of the windscreen into account –– its curvature, its rake, etc. –– “and we program those millions of pixels to take all that into account so that when you redirect the light towards your eyes you get a  very bright, private, easy-to-package, functionalized windscreen display.” The same display solution can be used on other glass surfaces in the car, such as the rear windows, to provide additional entertainment options for passengers.