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5 Minutes
Introduction: true 3D holograms you can touch
Researchers at the Public University of Navarra (UPNA) have unveiled a volumetric display system that produces authentic 3D graphics floating in mid‑air and—crucially—lets users reach in and manipulate those objects with their bare hands. Led by Dr. Elodie Bouzbib and principal investigator Asier Marzo, the multidisciplinary team developed FlexiVol, a prototype that combines high‑speed projection with elastic optical diffusers to enable safe, direct interaction with mid‑air holograms without headsets or AR glasses.
How FlexiVol works: optics, motion, and elastic diffusers
Volumetric displays create true 3D content by rapidly presenting many 2D image slices at different heights so that persistence of vision fuses them into a single volumetric object viewable from multiple angles. FlexiVol uses a projector capable of outputting thousands of frames per second synchronized to a fast‑oscillating sheet called a diffuser. Where conventional systems rely on rigid diffusers that can break or injure a user if touched, FlexiVol replaces them with elastic, deformable materials.
Elastic diffusers and real‑time correction
Elastic diffusers allow fingers and hands to safely deform the display surface and reach inside the rendered volume. Since the elastic material changes shape as it’s pushed, the team implemented on‑the‑fly image correction to compensate for mechanical deformation and optical distortion. The system characterizes the mechanical and visual properties of several diffuser materials, then adjusts the projected slices in real time so the hologram remains geometrically accurate even as the surface flexes.
Product features and technical highlights
- True 3D volumetric rendering visible without headsets or glasses.
- Elastic optical diffuser designed for safe, direct touch‑style interaction.
- High‑frame‑rate projection synchronized to diffuser motion to produce a continuous mid‑air volume.
- Real‑time deformation compensation to correct visual distortions caused by elastic materials.
- Interaction design space supporting natural gestures: grasping, dragging, docking, and tracing.
Comparisons: FlexiVol vs. existing volumetric displays
Commercial volumetric prototypes from companies such as Voxon Photonics and Brightvox produce compelling mid‑air visuals, but most do not support putting a hand into the display without risking damage to the optical surface. FlexiVol’s defining difference is interaction: by using compliant diffusers and dynamic image correction, it enables direct, touch‑like manipulations that feel natural—similar to dragging or pinching on a smartphone screen but in three dimensions.
Advantages and performance
The research team reports that direct interaction with FlexiVol offers faster and more precise completion of tasks like selection, docking, and tracing when compared with indirect input devices such as 3D mice. Natural manipulation leverages human stereoscopic vision and motor skills, improving spatial understanding and enabling intuitive control of virtual objects. Safety and durability are improved because elastic diffusers tolerate impacts and bending without catastrophic failure.
Use cases and market relevance
FlexiVol has broad potential across education, design, museum exhibits, collaborative workflows, and product visualization. In classrooms and technical training, students could disassemble and reassemble virtual engines or anatomical models by hand. Museums could deploy come‑and‑interact installations where visitors approach, grab, and examine artifacts rendered as 3D holograms. Collaborative engineering or medical teams might use shared mid‑air displays for group review without the need for VR headsets, enabling multi‑user interaction and natural gestural control.
Sample applications and interaction examples
The team demonstrated several prototype apps to showcase FlexiVol’s interaction affordances: a virtual pet that responds to being stroked and held, a landscape editor where users sculpt terrain with fingers, and object manipulation scenarios such as grasping a cube between thumb and index finger to move and rotate it. They also showed creative gestures like simulating walking legs using alternating fingers on a surface.
Why this matters for the future of display technology
Directly manipulable volumetric displays like FlexiVol bridge the gap between passive 3D visualizations and fully immersive VR systems. By removing the need for headsets while enabling natural touch interactions, these displays can accelerate adoption in public spaces, education, and professional contexts where shared, immediately accessible 3D information is valuable. FlexiVol highlights how material innovation paired with high‑speed projection and computational correction can unlock tangible, safe holographic interaction.
What’s next
Future work will refine material selection, increase resolution and brightness, and expand interaction techniques and software toolkits for developers. As the technology matures, expect improved commercial designs optimized for robustness, cost, and scalability—paving the way for real 3D holograms you can grab with your hands.
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