Numerous detection applications rely on the optical properties of atmospheric transparency windows around 1.6 and 2.3 µm. Thanks to advances in laser source technology, a large range of illumination techniques is now available to actively probe various scenes and objects, sometimes very far from the observer (applications to telemetry or identification by long range imaging) or screened by partially absorbing or diffusing media on the optical path (applications to biology and remote spectroscopy). Yet, the corresponding optical signal analysis generally suffers from the sensitivity of infrared detection devices. Following promising preliminary results recently obtained by the two partners, Thales Research & Technology (TRT) and the laboratoire Kastler-Brossel (LKB), the COSMIC project revisits the idea of frequency converting the multimode infrared signals of interest to shorter wavelengths by sum frequency generation with a secondary pump source. This makes infrared detection around 1.5 or 2.5 µm possible with all the technological and economic advantages of silicon based detectors. COSMIC stakes thus cover two aspects. Concerning modelling tools (derived from quantum metrology and applied to the specific case of imaging with classical noise), we need a trustworthy evaluation of the potential of multimode approaches for sum frequency detection, either to simulate active imaging systems (conversion efficiency, influence of pump laser design) or to study fundamental limits (parameter estimation by modal decomposition with applications to the separation of close incoherent sources and to detection at low light levels or through diffusing media). Experimentally, the partners also intend to exploit and secure their advance compared to competing European teams, following two complementary tracks. In the first part of the project, LKB will implement a modal sorter without frequency conversion and TRT will build an active imager around 2 µm based on multimode sum frequency generation on a CMOS camera and suited to the study of outdoor scenes at short range, resolved or not. The key point that will guide its design is the possibility to use the same pulsed fiber laser for both illumination and pumping of the frequency conversion stage. This advantage will be decisive to ensure a successful insertion in future systems. Those experiments will be merged in the second part of the project to study the mutual benefits of multimode frequency conversion and spatial mode selection in the case of weak and complex infrared signals at the core of COSMIC motivations. Those theoretical and experimental developments will be evaluated during the project with a constant goal of valorization toward detection applications. The partners have already identified a network of academic and industrial contacts able to feed the project with reliable specifications of practical cases, leading to an efficient selection of maturation paths for the COSMIC concept.