Chinese scientists have shown off a laser that can create ghostly Chinese characters out of thin air. Lasers have already been used to create a range of optical illusions, but previously they needed dust or clouds as a medium.

The researchers behind the new device say it can draw patterns anywhere by using ultra-short laser pulses to strip the electrons off air molecules and turn them into light, creating a ghostly image floating in mid air.

In one demonstration earlier this week at the Hongtuo Joint Laboratory of Ultra-Fast Laser in Wuhan’s optics valley, researchers created characters that were visible from any angle and which researchers could “touch” with their hands.

“With the brand new device, we can draw in the air without using paper and ink”, said Cao Xiangdong, lead scientist at the laboratory. 

The device works by focusing high-intensity laser pulses in the air to create plasma, or ionised gas, which emits energy in light form. To “light” the air, lasers need to reach an energy density of 100 terawatts (a trillion watt) per square centimetre.

The researchers hope that the technology will one day have a practical use in fields such as high-precision manufacturing, brain imaging, medical instruments and quantum computing.

Last year, another femtosecond laser based device produced by the lab, a disinfection machine, was validated by Wuhan University’s National Laboratory of Viruses for use in killing viruses and bacteria, including the coronavirus.

Source: South China Morning Post