ESA plans to launch its FLEX mission in 2025. The aim is to collect data on the Earth's vegetation from space. For the spectrometer on board the satellite, researchers from the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena have developed and manufactured a double-slit assembly with exceptional accuracy as well as two high-precision mirrors. The double slit will be presented at SPIE Photonics West in San Francisco from January 30 to February 1.