Luminit showed both an AR-HUD and a reflective in-plane HUD at the Vehicle Displays and Interfaces conference in Detroit. Both are based on their holographic mastering and replication technology.
In this transcript, Chris Chinnock interviews Anthony Silvestris at the Luminit booth, exploring advanced holographic optical elements (HOE) for automotive windshields.
AR Head-Up Display (Laser Projector)
Luminit is showcasing an augmented reality (AR) HUD that overlays digital data onto the road using laser projection.
- Holographic Recording: The system uses a holographic optical element recorded to match specific projector wavelengths.
- Optical Path: A laser projector images onto an under-dash diffuser, which then reflects off the HOE in the windshield.
- Virtual Depth: The relationship between the diffuser, projector, and HOE dictates the field of view and virtual image distance.
- Laser Characteristics: While laser projectors offer high brightness, they can introduce a “speckly” appearance that the system must manage.
Solar Flare Mitigation
One major challenge with diffractive optics in windshields is “solar flare,” where sunlight creates distracting rainbows.
- Patented Solution: Luminit has a patent for a system that traps collimated sunlight.
- Light Guiding: Instead of reaching the driver’s eyes, stray sunlight is guided to the edge of the substrate.
- Proof of Concept: A successful “sanity check” demo was delivered to an OEM to prove the physics work.
Future Production & Scalability
Luminit aims to move from manual prototypes to fully integrated, mass-produced windshields by 2028–2030.
- Lamination: For production, the holographic film must be laminated between layers of safety glass.
- Pillar-to-Pillar Displays: Future versions could feature one large substrate with multiple recorded zones for AR and “in-plane” HUDs.
- Cost Efficiency: They are exploring “switchable Bragg gratings” to allow a single laser source to power multiple projectors.
In-Plane HUD & Mastering
The “lower” or in-plane display works differently, acting more like a transparent screen on the glass itself.
- Mastering Process: Luminit uses its 20-year legacy in Light Shaping Diffusers to record a diffractive version of a physical microstructure.
- Precision Engineering: The master is recorded using an analog process, which is then mass-produced via a roll-to-roll copy method.
- Customization: By tuning the “diffuser prescription,” they can precisely define the eyebox and field of view for the driver or passenger.
