12 Jan. Nanostructures that promise better weather forecasts
On July 1, 2025, the European Space Agency (ESA) launched the MTG-S1 satellite from the third generation of the Meteosat series. The geostationary satellite is expected to significantly improve the accuracy of weather forecasts for Europe. MTG-S1 carries several scientific instruments, including the Copernicus Sentinel-4 spectrometer. According to the researchers in charge, this instrument collects detailed hourly data on the three-dimensional distribution of trace gases such as ozone, nitrogen dioxide, and sulfur dioxide, as well as aerosols in the atmosphere above Europe.
From USP laser to space spectrometer
An essential component of this spectrometer is a high-precision reflection grating from the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. “The technology used is originally based on gratings for compressing ultrashort laser pulses,” explains Dr. Falk Eilenberger, head of the department Micro- and Nanostructured Optics at Fraunhofer IOF. “Our goal was to develop extremely robust gratings with maximum reflectivity and, at the same time, high angular dispersion and low polarization dependence.”
The precision gratings are manufactured in several steps, explain the researchers. First, various dielectric layers are applied to a substrate, with the top layer consisting of silicon dioxide (SiO2). Next, a nanostructure is created using electron beam lithography and reactive ion etching. This is followed by lithographic coating with black chromium for the aperture before the component is cut into its hexagonal shape and assembled with an accuracy of a few micrometers.
A scanning electron microscope shows the custom nanostructure
of the NIR grating for the Sentinel-4 instrument. Image: Fraunhofer IOF
Space technology from Germany
The researchers at Fraunhofer IOF can draw on decades of experience and an extensive portfolio of space-certified technologies. Eilenberger: “Fraunhofer IOF’s multiple participation in various space missions is testament to the ongoing development of relevant expertise. Some of the processes were custom-developed and qualified for special missions. What sets us apart is that all the necessary process steps, from design and manufacturing to system integration, can be carried out right at Fraunhofer IOF.” For example, the institute developed a diamond beam splitter with a special anti-reflective nanostructure for the ESA’s Forum mission, which is planned for 2027. For the CO2M mission, also an ESA initiative, Fraunhofer IOF is supplying spectrometer optics, each consisting of a grating and two prisms. These components were joined using plasma-activated surfaces without an intermediate layer.
Source and image: www.iof.fraunhofer.de