Holography in public transport: the future of passenger information
The HÜBNER Group and ZEISS Microoptics are bringing holographic displays to buses and trains: passenger information is projected directly onto the windows.
Passenger information holographically projected onto the window Photo: ZEISS Microoptics
Despite the widespread use of travel apps, availability of real-time information in public transport remains a decisive factor for passenger satisfaction. In 2022, the Fraunhofer Institute IESE found that around 63 per cent of passengers rated the flow of information on public transport as inadequate. Manufacturers and operators face the challenge of providing reliable, clearly visible travel information directly in vehicles.
Transparent holographic displays are used to project passenger information directly into the passenger’s field of vision. Window and door systems serve as carriers for holographic films, which have a transparency of over 90 per cent. Comparable OLED systems only achieve around 40 per cent transparency. This high level of transparency enables a largely unrestricted view to the outside, while route information is displayed at the same time. In addition, information about topics such as places of interest or shopping facilities can be displayed along the route. The positioning and design of the projection surfaces can be flexibly adapted to different requirements.
A major advantage of this technology is a considerable saving of space inside the vehicle. By using the holographic films, a projector in the ceiling area transforms the window into a display. The projector already has the supply power and information to be displayed, so that integration is simple and space saving. In contrast to conventional solutions, there is no need for complex cabling and separate attachments, thus also reducing maintenance costs. Integration into window panes protects the equipment from external influences. The display quality remains high and the view to the outside is not impaired.
ZEISS uses tuneable lasers from HÜBNER Photonics to produce the holographic optical elements. T he finished holographic films are integrated directly into the window panes. The system makes real-time information in vehicles visible at all times and thus fulfils the requirements for availability and currentness of information during operation. The holographic applications can be integrated into both existing and new vehicle concepts.