A patent rotated a screen to fill a dome with light

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What the patent documents, dated to the day

On 29 April 2003, the US Patent and Trademark Office granted US Patent 6,554,430, 'Volumetric three-dimensional display system', to Actuality Systems, the company Gregg Favalora co-founded. The patent describes a specific, concrete mechanism, not an abstract concept: a circular projection screen spinning inside a transparent dome, with the image-generating optics kept stationary below the platform, outside the viewer's line of sight, so only the rotating screen itself is visible through the dome.

What creates the image, and the viewing conditions it needs

A stationary projector updates the image on the spinning screen continuously; the patent states the system projects updated two-dimensional image slices onto the screen 'at least 4,000 times per second'. The patent's own explanation of why this looks solid rather than a blur is direct: 'persistence of the human visual system integrates these two-dimensional image slices into a three-dimensional volume-filling image'. Because the screen genuinely sweeps through the whole enclosed volume and the image is redrawn at every angle as it spins, the resulting volumetric image can be viewed from any position around the dome, by multiple viewers simultaneously, with no glasses, headset or head tracking required. This is a real, physically distinct point in space emitting light, unlike a projected illusion reflected off a flat surface.

What later documentation confirms and what it does not

Two years after the patent granted, Favalora's own 2005 survey in IEEE Computer situates this exact product, marketed as Perspecta, within the wider field of volumetric displays, alongside competing static-volume approaches. A current manufacturer, Voxon, describes its own product on its website, as retrieved 16 September 2026, in near-identical mechanical terms: 'swept-volume LED technology: a high-speed surface sweeps a 2D image through 3D space so fast that persistence of vision builds a true, walk-around voxel cloud'. What none of these documents establishes is true mutual occlusion between objects within the volume; a rotating-screen display, like the static-volume alternative, draws each slice independently, so one voxel does not automatically block light from a voxel behind it the way a solid object would. That constraint belongs to the swept-volume class generally, not to any single implementation.

Questions to bring to a demo

• What is the actual screen rotation speed and image update rate, and how does that limit achievable voxel resolution?
• Does a foreground object in the volume visibly and correctly block objects positioned behind it?
• Is the enclosure a sealed, transparent dome, and does the moving screen restrict where viewers can safely stand?

The 2003 patent's spinning-screen mechanism, verified in its own claims and echoed almost exactly in a current manufacturer's own description two decades later, set the durable template for swept-volume volumetric displays: sweep a surface fast enough, and persistence of vision does the rest of the work.