Fraunhofer Institute for Photonic Microsystems
Earth observation data is becoming increasingly important for our understanding of the planet and for overcoming socio-ecological challenges - for example in the area of environmental monitoring. Currently, the methods for data acquisition and processing from space are limited by long recording times (up to several days per measurement), a low spatial resolution (approx. 1 km) and the usable spectral range (especially in the visible range). Novel camera systems based on spatial light modulators can provide a remedy here, which were realized and tested for the first time within the EU project SURPRISE. Fraunhofer IPMS contributed to the project with its many years of expertise in the field of area light modulators and planned the development of the first space-qualified spatial light modulator that was manufactured entirely in Europe.
The special CS imaging technology used in the project for Earth observation requires special components. Spatial light modulators are the most suitable solution for this task because variable image patterns can be generated at high speed. These patterns are overlaid with the observation scene and recorded by single pixel detectors. The spatial light modulators developed by Fraunhofer IPMS consist of thousands – or even millions – of individual movable mirrors, each only a few micrometers in size. Fraunhofer IPMS uses its extensive experience in the development and manufacture of spatial light modulators in order to find the best solution for the specific requirements in the project. The biggest challenges here are the space capability of all components and the coverage of a broad spectral range from visible to mid-infrared. The main objective of the project was to develop a demonstrator. Core parameters: The spectrally broadband operating range - in the visible (VIS), near-infrared (NIR) and mid-infrared (MIR) - improved performance in terms of resolution on the ground as well as innovative data processing and encryption functionality on board.
The innovative Compressive Sensing (CS) technology was used for this. It makes it possible to capture a two-dimensional image using a single-pixel detector. This is particularly interesting for the mid-infrared, as there are no suitable 2D detectors available in this spectral range. At the same time, CS offers advantages when processing large amounts of data as well as native data encryption.
The special CS imaging technology used in the project for earth observation required special components. Spatial light modulators are the most suitable solution for this task, as variable image patterns can be generated at high speed. These patterns are superimposed on the observation scene and recorded by single pixel detectors. The spatial light modulators used at Fraunhofer IPMS consist of thousands or even millions of individual moving mirrors, each only a few micrometers in size. In order to find the best solution for the special requirements of the project, Fraunhofer IPMS used its more than 25 years of experience in the development and manufacture of spatial light modulators. The biggest challenges were the space suitability of all components and the coverage of a broad spectral range from visible to mid-infrared.
