Impressed by an Ancient Light Trick, “Flat Magic Window” Technology Could Help a New Kind of 3D Screen

Scientists Produce Flat Magic Window With Liquid Crystals

For the initial time, experts empolyed liquid crystals to construct a flat magic window — a transparent device that produces a concealed graphic when light shines on it. The technological innovation represents a novel twist on a very old light-weight trick.

Countless numbers of decades in the past, artisans in China and Japan produced bronze mirrors that looked like frequent flat mirrors when viewing one’s reflection but generated one more picture when illuminated by immediate sunlight. It took experts right until the early 20th century to figure out that these gadgets operate because an image forged into the back of the mirror makes little floor versions that trigger the image to kind – and it took engineers until now to implement the very same basic principle to liquid crystals for substantial-tech displays.

“The magic window we developed seems perfectly flat to the bare eye but, in simple fact, has slight variants that generate an graphic in reaction to light-weight,” mentioned investigate crew leader Felix Hufnagel from the College of Ottawa. “By creating the window to be reasonably sleek, the graphic that is produced can be witnessed above a substantial range of distances from the window.”

In Optica, Optica Publishing Group’s journal for higher-influence exploration, Hufnagel and colleagues describe the procedure they produced for building clear liquid crystal magic windows that can produce any wanted impression. The system can also be utilised to build magic mirrors that replicate, alternatively than transmit, mild to create an image.

“Using liquid crystals to make magic home windows or mirrors could a person day make it possible to build a reconfigurable model for generating dynamic creative magic home windows or movies,” stated Hufnagel. “The means to get a extensive depth of target could also make the technique practical for 3D displays that create steady 3D photographs even when considered from unique distances.”

Generating magic with liquid crystals

Whilst scientists have recognized for many years that the historical bronze magic mirrors formed visuals as a end result of little area variants, it was not right until 2005 that Michael Berry, a mathematical physicist at the

Stable images over multiple distances

“On a conceptual level, the theory developed by Berry was instrumental in determining how these liquid crystals must be oriented to create an image that is stable over a large distance,” said Hufnagel. “Our use of flat optical elements and a liquid crystal pattern with gentle variations prescribed by Berry’s Laplacian image theory allows the magic windows to appear normal, or flat, when one looks through them.”

After fabricating a magic mirror and window, the researchers used a camera to measure the light intensity patterns produced by both devices. When illuminated with a laser beam, both the mirror and window produced a visible image that remained stable even as the distance between the camera and the mirror or window changed. The researchers also showed that the devices created images when illuminated with an LED light source, which would be more practical to use in real-life applications.

The researchers are now working to use their fabrication approach to create quantum magic plates. For example, two of these plates could create entangled images which one could use to study new quantum imaging protocols. They are also exploring the possibility of fabricating magic windows using approaches other than liquid crystals. For instance, using dielectric metasurfaces to make a magic window device could reduce its footprint while increasing bandwidth.

Reference: “Flat Magic Window” by Felix Hufnagel, Alessio D’Errico, Hugo Larocque, Fatimah Alsaiari, Jeremy Upham and Ebrahim Karimi, 5 May 2022, Optica.
DOI: 10.1364/OPTICA.454293