Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB 
Short Description of the Project
The project aims to develop a novel quantum rangefinder that determines distances using entangled photons. Unlike conventional laser rangefinders, the system emits light that blends into the natural background and is virtually undetectable to third parties as active illumination. The useful signal can only be identified through the partner photons measured within the device. The central challenge lies in precisely filtering these extremely weak return signals out of the noise − even over long distances and under real-world environmental conditions − and integrating them into a mobile, robust, and miniaturizable measurement system.
Project Goals
The goal of the project is the development and experimental demonstration of a quantum rangefinder capable of precisely determining distances without being detectable due to its active illumination. To this end, a mobile prototype is being built at the IOSB, measurement and data processing are being further developed, and range measurements are being conducted initially in the laboratory and subsequently over distances ranging from 100 m to 1000 m. In addition, the system’s undetectability by infrared cameras will be experimentally verified, and the technology’s miniaturization potential, energy efficiency, and commercialization prospects will be evaluated, while laying the groundwork for intellectual property rights and follow-up applications.
Project Results
To date, the project has established the technological foundations for a mobile quantum rangefinder (QRF): The existing setup from quantum ghost imaging is being further developed into the QRF, detection is being improved using modern SPAD technology, and the measurement and evaluation software is being rebuilt. This paves the way for initial range demonstrations at night extending to the kilometer range and for the experimental verification of non-detectability. If this verification is successful, it will result in a highly relevant technological advantage with strong transfer potential for defense applications, intellectual property rights, follow-up projects, and, in the future, civilian mapping.