Using their technique, Zhu and his colleagues made small pictures of the Mona Lisa and a portrait of Danish physicist Niels Bohr, as well as a simple photograph of a woman and a bridge, each measuring about 1 inch (2.5 centimeters) across.
To mass produce this kind of printer, researchers would need to make laser technology smaller and might need a different material for the layers of sheets, the researchers said. That material would need to have a high refractive index, meaning it bends light a lot and absorbs light at the wavelength chosen for the laser, they added. In their experiments, the scientists chose green light for the wavelength and experimented with silicon for the material, which Zhu said doesn't absorb green laser light as efficiently.
Even germanium, though, is a possibility, because it isn't too expensive. "A few kilograms can cover a football [soccer] field," he said, noting that the germanium and polymer layers are only up to 50 nanometers thick. Germanium, though, isn't necessarily the best option, because it doesn't produce green colors well, Zhu said.