Institut für Automatisierungstechnik

Optical Correlator Testbed for High Resolution Imaging from Geostationary Orbit

05/2013 - 04/2017 
Prof. Dr. techn. K. Janschek 
Dr.-Ing. V. Chernykh, Dr.-Ing. S. Dyblenko, M.Sc. S. Grzelak 
Astrofein GmbH (Berlin, Germany)
CSE (Zurich, Switzerland)
Fraunhofer IPMS (Dresden, Germany) 

Earth observation from the geostationary orbit (GEO) offers a number of advantages with respect to the Low Earth Orbit (LEO) imaging missions (short revisit time, continuous data downlink, possibility of real time observation; optimal using of clouds clearance, etc.). The disadvantages are the necessity to use a telescope with an approximately 45 times larger focal length to provide the same ground resolution at nadir as achieved with a LEO satellite(due to 45 times larger orbit altitude). Besides the difficulty of the large optics realization, it results also in 45 times larger sensitivity to telescope pointing instability. For the high resolution GEO observations (few meters ground sampling distance), an ultra-high pointing stability during integration (well below 0.1 arc second) will be required to avoid motion blur and MTF degradation.

The project is devoted to an analysis of a group of alternative solutions for pointing instability compensation based on the precise real time measuring of pointing vector during integration time with onboard optical correlator. For each scene a sequence of short-exposed sub images will be taken, they will be mutually registered and stacked; thus the mechanical pointing error will be compensated. Using this technology the requirements for the satellite attitude stability can be significantly relaxed, what is particular essential for high resolution GEO imaging mission.

The project makes use of the hardware model of the Optical Correlator (OCOR Model), developed and manufactured within the frame of previous activity (Optical Correlator for Push-Broom Imagers, funded by ESA / GSTP programm).

In particular, the project activity will include:

  • Development of the concept of imaging system with optical correlator for a geo-stationary high resolution imaging mission.
  • Development and validation of a testbed for real-time testing of an optical correlator for high-resolution imaging from geostationary orbit. The testbed will include a Test Image Generator to simulate scene images like they will be acquired by optical imagers in GEO orbit, hardware OCOR Model to perform mutual registration of the sub-images, and Image Processing Unit to integrate the sub-images.
  • Development of the System Performance Model.
  • Conceptual design of a vacuum compatible electronic assembly for OCOR Model.
  • Vibration tests on the OCOR Model hardware.
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