Light needs space. A camera lens sits several centimeters from the sensor so the rays have room to focus. Now, that gap has been squeezed to the thickness of a sheet of paper, and light still behaves as if it had traveled its rightful centimeters. That's what 'spaceplates' do: flat elements that mimic free-space propagation.

Until now, these plates had an annoying flaw: the more you compress space, the narrower the field of view. It's like trying to see a room through a keyhole: you see far, but only a tiny sliver. A research group has now built a plate that overcomes this limitation. They stacked several layers of a metasurface — an artificial material patterned at subwavelength scale. Each layer nudges the light a bit, and together they create the illusion of a thick slab of glass. The physical thickness of the stack is about 80 micrometers (thinner than a human hair), but to an infrared beam it looks like 1.09 millimeters. The compression factor is roughly 14.

The secret is that the layers don't just repeat each other. Their thicknesses were tuned by a computer algorithm that sifts through millions of options until it finds a combination that perfectly mimics empty space. This approach was previously used for single metalenses, but it's the first time it's been applied to spaceplates. The result is a plate with a numerical aperture of 0.13 (a measure of the angle at which it collects light). Not a record angle, but enough for real devices.

Why does this matter? The thickness of a smartphone camera has long hit the limits of optics. A spaceplate lets you remove almost all the air gap between the lens and the sensor. The same logic applies to augmented reality glasses: you can project images directly into the lenses without adding thickness. A millimeter of compressed space is the first step toward optics that barely take up any room.