New invention transforms any smartphone or TV display into a holographic projector

Researchers have created holograms using the light emitted from an ordinary smartphone screen — effectively turning an iPhone into a holographic projector.

Using a device called a spatial light modulator (SLM), scientists transformed a 2D image displayed on an iPhone 14 Pro into a 3D hologram. They detailed their findings in a study published April 2 in the journal Optics Letters.

The researchers employed a technique they called a "cascade of holograms," whereby the light from a static image is repeatedly modified to create a multi-layered, 3D image.

In the study, the cascade began with a static color image shown on an iPhone. Light waves emitted from it were refined through the SLM — a device used to control and adjust the phase (timing), amplitude (strength or brightness) and polarization (direction) of light waves. Using the SLM, scientists progressively refined and layered the light waves to build up the 3D image step-by-step.

To achieve the holographic effect, the scientists had to determine the specific adjustments of light needed to create the 3D hologram from the image displayed on the iPhone's screen.

This involved working backwards from the desired output to determine the specific adjustments needed in the light's phase and amplitude at each step of the journey, from the iPhone display through the SLM, to recreate the hologram accurately.

They captured images at two key points using a color image sensor. The first point was at the focal point of a Fourier transform lens (FTL) — a special type of optical lens designed to precisely focus light into clear images.