Researchers Build Flat Magic Window With Liquid Crystals
For the to start with time, researchers empolyed liquid crystals to assemble a flat magic window — a clear machine that produces a concealed graphic when light-weight shines on it. The technology represents a novel twist on a extremely old light trick.
Hundreds of a long time in the past, artisans in China and Japan manufactured bronze mirrors that seemed like standard flat mirrors although viewing one’s reflection but generated a different impression when illuminated by direct sunlight. It took researchers right until the early 20th century to figure out that these devices perform for the reason that an image forged into the again of the mirror makes small floor variations that result in the graphic to form – and it took engineers right up until now to use the identical basic principle to liquid crystals for high-tech displays.
“The magic window we created seems perfectly flat to the naked eye but, in truth, has slight variations that create an image in response to mild,” said exploration crew leader Felix Hufnagel from the University of Ottawa. “By developing the window to be rather sleek, the impression that is developed can be noticed in excess of a substantial selection of distances from the window.”
In Optica, Optica Publishing Group’s journal for high-impact investigation, Hufnagel and colleagues describe the method they created for producing transparent liquid crystal magic home windows that can make any wanted impression. The system can also be employed to make magic mirrors that reflect, relatively than transmit, gentle to make an image.
“Using liquid crystals to make magic windows or mirrors could just one day make it feasible to create a reconfigurable edition for manufacturing dynamic artistic magic windows or flicks,” explained Hufnagel. “The capability to receive a lengthy depth of emphasis could also make the solution helpful for 3D displays that develop steady 3D images even when considered from different distances.”
Creating magic with liquid crystals
While scientists have understood for many years that the ancient bronze magic mirrors formed photographs as a final result of little floor versions, it was not until finally 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.