The spaceplate is a nanotechnology-based optical element that manipulates light rays based not on its position, but on its angle. A beam incident on the spaceplate at a particular angle will emerge at that same angle but be transversely translated by a certain length. The result is that spaceplate acts to effectively compress the space required for the light to travel before it hits the image sensor, thus reducing the length of the lens barrel. In the illustration above, the space depicted in yellow has been compressed by the spaceplate, resulting in a much shorter lens.
Adding a spaceplate to an imaging system such as a standard camera with a fixed lens will shorten the camera thickness. Added to a lens, it will shorten the length of the lens barrel (and therefore its weight). An ultrathin monolithic imaging system can be formed by integrating a metalens and a spaceplate directly onto a sensor (thus removing any lens “bump”) on a cellphone.