Alexander Lippert, a chemist at Southern Methodist University in Dallas, has developed a new low-cost technology that uses photoswitch molecules to create 3D light structures. It could have uses in biomedical imaging, education, entertainment and engineering.
“Our idea was to use chemistry and special photoswitch molecules to make a 3-D display that delivers a 360-degree view," Lippert said. "It's not a hologram, it's really three-dimensionally structured light."
Unlike current methods of 3D viewing, which trick the eyes into perceiving depth, Lippert’s technology creates structures of light with genuine depth. "Our display is not tricking your brain,” said Lippert. “We've used chemistry to structure light in three actual dimensions, so no tricks, just a real three-dimensional light structure. We call it a 3-D digital light photoactivatable dye display, or 3-D Light Pad for short, and it's much more like what we see in real life.”
It works using a molecule that switches between being fluorescent and non-fluorescent when exposed to ultraviolet light. However, once these molecules have been activated, they normally take minutes or hours to return to their original state.
Lippert’s team discovered that by adding a substance called trimethylamine, they could create photoswitch molecules that could switch on and off at will. “We wanted the rate of reaction with UV light to be very fast, making it switch on,” he said. We also wanted the off-rate to be very fast so the image doesn't bleed.”
The researchers created a 50mm cube of quartz glass containing the new molecules, and placed it at the intersection of two beams of light – one UV and one green. This allowed them to create three-dimensional images and animations like the ones Lippert had seen in Star Wars as a child.
“As a kid I kept trying to think of a way to invent this," Lippert said. "Then once I got a background in chemistry molecules that interact with light, and an understanding of photoswitches, it finally dawned on me that I could take two beams of light and use chemistry to manipulate the emission of light.”
The technology could be used across a number of industries. Manufacturing companies could render their products in real 3D to tweak them and discuss the designs. It could be used for 3D video calling, or reconstructing landscapes for mapping or military purpose.
There are potential medical applications too. “With real 3-D results of an MRI, radiologists could more readily recognise abnormalities such as cancer,” Lippert said.
He says the system is much cheaper than other technology because it has fewer moving parts. “For a really modest investment we've done something that can compete with more expensive $100,000 systems," Lippert said. "We think we can optimise this and get it down to a couple thousand dollars or even lower.”
The next steps are to increase the resolution of the system, as well as adding more colours – it is currently monochrome. Lippert also hopes to create bigger, table-top displays and optimise the projector technology. He is even exploring the possibility of creating aerosols containing the photoswitch molecules for screens you can spray into the air.