With the sound of piercing, "Hongtuo", "five pointed star" and other Chinese characters and graphics are displayed in the air, which can be seen with the naked eye and touched with both hands. On July 19, the reporter witnessed this sci-fi scene in Hongtuo ultrafast laser Joint Laboratory of Wuhan East Lake high tech Zone. "Without paper and ink, a beam of light can paint out of thin air." Caoxiangdong, director of the laboratory, said that the team's newly developed high-energy, high peak power femtosecond laser, with a peak power density of megawatts, gathers a "fastest light" and "lights up" the air. Breakthrough in laser display from "0" to "1". At present, most 3D display technologies use binocular vision differences and human brain virtual synthesis to present "Pseudo 3D images" on the screen. The latest 3D display technology uses the three-dimensional physical space to render graphics. Each voxel (corresponding to the pixels in the plane display) emits light or reflects light through the laser, and arranges images in the three-dimensional space, so that the audience can watch the 3D image from all angles without dead angles. The 3D image formed by femtosecond laser penetrating the air is real. Cao Xiangdong introduced that this real 3D display technology based on femtosecond laser-induced plasma focuses the femtosecond laser with high peak power, reaches 100 terawatts per square centimeter, and then breaks through the air to induce the formation of luminous plasma. The 3D scanner is used to scan the laser beam, arrange and combine the luminous lattice, and form various words or patterns in the air. Compared with traditional laser display, femtosecond laser display technology has obvious advantages. Its display medium is air, which does not need a screen, water mist, etc., and can present 3D images directly in the air. At the same time, femtosecond laser has shorter pulse duration than nanosecond laser (1 nanosecond is 1 billionth of a second, 1 femtosecond is 1 millionth of a nanosecond), lower energy required, shorter single point residence time and higher safety. What is the difficulty of femtosecond laser display technology? "Today's appearance comes from more than ten years of painstaking research behind the light and shadow." Cao Xiangdong said that femtosecond laser was once known as one of the four great inventions of Optics Valley. He and his team were committed to the research and development of core cutting-edge technologies and application technology in the ultrafast laser industry, and all key core technologies were localized to achieve complete independence. Breakdown of air requires an energy density of 100 terawatts per square centimeter, that is, femtosecond laser can achieve 100 terawatts of energy output in the area of the nail cap, and ionize air is released in femtosecond time scale. "Lighting up" the air reflects the comprehensive technical level of femtosecond laser. While relying on strong peak power, the average power is only dozens of watts. "Our in-flight imaging femtosecond laser technology has achieved a leading level of display brightness. The customer compared the products of many companies at home and abroad, and finally chose us." Cao Xiangdong said. According to Cao Xiangdong, the team adopts the self-developed advanced femtosecond laser technology. In the future, it will further upgrade the femtosecond laser power and realize the real 3D display in the air with a large format by complex editing and controlling the temporal and spatial distribution of femtosecond laser pulses, accurately adjusting the characteristic parameters such as the brightness, color and duration of voxels. (Xinhua News Agency)