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Engineers at the University of California, Los Angeles have developed a “lying mirror” that can reflect an image completely different from the object actually positioned in front of it. The experimental technology could eventually be used to disguise sensitive equipment by making it appear as something ordinary.
Unlike a conventional mirror, which reflects incoming light in a way that preserves the appearance of the scene, the new device manipulates that light to produce a predetermined image. The current system is only a proof of concept, but researchers believe the approach could eventually enable a new form of optical camouflage.
The technology was developed using a structured surface containing microscopic features that alter the phase of reflected light. Deep-learning techniques were used during development to determine how the surface should be structured to transform different incoming images into a specific visual output.
In computer simulations, researchers designed mirrors that could transform images of clothing into a bag, different handwritten numbers into the number 8, and simple drawings into a panda face. The systems also produced recognizable decoy images when presented with pictures they had not encountered during training.
The team then built a physical version designed to transform handwritten numbers into an image of the number 8. The experimental setup used an array of tiny mirrors and successfully operated using separate red, green and blue wavelengths, as well as all three together. Another design demonstrated operation across a broader range of visible wavelengths.
The concept resembles a hologram in that it carefully manipulates the phase of light to create a desired image. However, instead of simply displaying a stored picture, the lying mirror transforms the visual information arriving from the scene into a predetermined output.
The biggest challenge is making the technology work outside controlled laboratory conditions. The demonstration relied on coherent light and precise optical alignment, while sunlight and ordinary environmental lighting are generally incoherent.
A practical version could therefore require multiple layers of optical structures capable of collecting and combining light arriving from different directions. Researchers say such a system could potentially be used for security, defense and entertainment.
One possible application is camouflage. Rather than physically concealing an object, a future lying mirror could make sensitive equipment appear to be an ordinary, unremarkable object, potentially preventing observers from realizing that anything valuable is present.
The researchers emphasize that substantial engineering work remains before such a device could operate in everyday environments. For now, the lying mirror is an intriguing demonstration of how engineered surfaces and machine learning can manipulate light in ways that make a familiar optical device appear to “lie.”
