All imaging systems consist of two main components: lenses and the spaces between them. The distances between lenses are just as critical to image formation as the lenses themselves. They can easily be greater than the summed thicknesses of the lenses. Now researchers have developed an optic called spaceplate to address this dominant contribution to the size of many optical systems.
The spaceplate, an optical element, can replace the distances between lenses. This element would occupy a physical thickness while propagating light for an effective length greater than the thickness, where the ratio between these two quantities is the compression factor of the plate.
Some metamaterials, such as those based on transformation optics, already feature the compression of electromagnetic fields. Though compression of propagation distance can be implicit in these works, this compression has not been an aim unto itself, particularly for reducing the length of imaging systems. Many optical devices implicitly use imaging or spatially manipulate light using its propagation in integrated optics. These devices (e.g., grating spectrometers or multimode interferometers) could be shortened through a spaceplate, leading to significant practical advantages.