Researchers create first layered holographic display using a smartphone

A true holographic display that can be used in every day devices has been a holy grail for decades. Now researchers have created the first layered holographic display with the help of a smartphone.

Okay, first off, yes there have been so-called 'holographic' displays created with smartphones before, the most infamous example of which was the ill-fated RED Hydrogen smartphone. As far back as 2015, some innovative DIY types were creating a projection effect of their own. However, unlike those, which were often homemade jobs made using some sellotape and clear plastic, this new attempt from Tokyo University is a layered display and uses actual, you know, real science and stuff.

In a paper titled "Computer-generated holography with ordinary display", the researchers from the University of Tokyo outline a breakthrough new method of creating a holographic display that eschews the use of lasers and could make such displays more practical for a wider variety of devices.

Reducing the complexity and cost of holographic displays

Using laser for holographic displays is complex and expensive, making practical take-up and development difficult. Rather than using two spacial light modulators (SLM), which control the wavefronts of the light and is the method used in previous non-laser systems, the Tokyo University researchers have developed a system that only requires only a single SLM in combination with software algorithms.

An experimental simulation demonstrating an image of a mandrill, showing the continuous transition between two layers to create the 3D effect. Image: Ryoichi Horisaki, The University of Tokyo.

Reducing the complexity in this way means that existing displays, such as those found on smartphones, can now be used to create a holographic image. Otoya Shigematsu, one of the research team explains, “We compute holograms by modeling incoherent light emitted from the mobile phone screen and display the holograms on an iPhone and a spatial light modulator, respectively.”

So, how does it all work? Simply, light from the smartphone screen passes through the SLM to create the multiple levels of the 3D image. By modelling the incoherent light propagation from the screen, the data can be used to create an algorithm that coordinates the light emitting from the LCD screen with the SLM.

With the numerical simulations done with an image of a pepper and a mandrill, the team than moved onto a real world test to see if the method would work as hoped. Shegematsu said, "...we were worried about whether the reproduction of the two layers would work well in actual optical experiments, so we were delighted when the mandrill made eye contact with us,”

Holographic displays are a technology that could offer real world uses in industries such as medicine, weather forecasting, and the military, as well as the creative industries. The fact that real progress has now been made that can drastically reduce the complexity and cost means that maybe now development can accelerate away from the apparent development stagnation that has currently set in.