Laser Imaging System Achieves Millimeter-Scale Text Reading Over a Kilometer Using Intensity Interferometry

Researchers at the University of Science and Technology of China, in collaboration with international colleagues, have developed a groundbreaking laser-based imaging system capable of reading text just a few millimeters tall from a distance of over 1.3 kilometers. The technology leverages active intensity interferometry (AII), a method traditionally used in astronomy to measure tiny angular distances by analyzing the correlation of light intensities from multiple detectors. Unlike conventional imaging, which depends on pristine lenses to collect clear light waves, this new approach uses eight phase-independent laser emitters to create pseudothermal illumination. The reflected light from a distant target is captured by two or more telescopes, and advanced algorithms reconstruct the image with remarkable precision.

In a practical demonstration, the team carved the letters ‘USTC’ into blackened aluminum sheets covered in retroreflective material and placed them 1.36 kilometers away. The system successfully resolved these millimeter-scale letters, achieving a resolution of 3 millimeters—14 times finer than the diffraction limit of a single telescope at that distance. This breakthrough allows the device to cut through atmospheric turbulence and overcome optical flaws, making it ideal for long-range, high-resolution imaging in challenging environments. While the technology remains in the research phase, its potential applications include surveillance, remote sensing, and disaster monitoring. The findings were published in Physical Review Letters.