The DLR Earth Sensing Imaging Spectrometer (DESIS) is a new space-based hyperspectral sensor developed and operated by a collaboration between the German Aerospace Center (DLR) and Teledyne Brown Engineering (TBE). DESIS will provide hyperspectral data in the visible to near-infrared range with high resolution and near-global coverage. TBE provides the platform and infrastructure for the operation on the International Space Station (ISS), DLR has developed the instrument. This paper gives an overview of the design of the DESIS instrument together with results from the optical on-ground calibration. In-flight calibration, stability of dark signal and rolling vs. global shutter analysis will be presented.
This paper focuses on the calibration and verification of the DESIS (DLR Earth Sensing Imaging Spectrometer) detector for the VIS/NIR (VNIR) spectral range. DESIS is a hyperspectral Instrument for the international space station, developed from the German Aerospace Center (DLR) and operate by Teledyne Brown Engineering (TBE). TBE provides the MUSES platform, on which the DESIS instrument will be mounted. The primary goal of DESIS is to measure and analyse quantitative diagnostic parameters describing key processes on the Earth surface. The main components of the sensor, the detector and the focal plane, were examined and verified. This allows predictions about the future data quality. The verification and validation of components and the entire system is an important and challenging task. The verification of the detectors is necessary to describe the characteristics of the detector according to predetermined specifications. The quantities to be examined are e.g. the quantum efficiency, the linearity of the detector, the pixel response non-uniformity (PRNU) and the dark current noise. For this purpose, specially calibrated integrated spheres are used that allow traceability of the measured data. With these information, the future performance of the sensor can be estimated using simulations.
Hyperspectral instruments are fundamental tools in remote sensing for environmental control and precision farming. For hyperspectral sensors often conventional optical designs based on grating or prism spectrometers are preferred. These instruments meet the system and mission requirements. From the provided data high quality information can be derived. However, more and more data is being offered by low-cost missions. This will establish new business models and data providers. This article is intended to provide an overview of current low cost sensors for hyperspectral applications.
The DLR Earth Sensing Imaging Spectrometer (DESIS) is a new space-based hyperspectral instrument developed by DLR and operated under collaboration between the German Aerospace Center (DLR) and Teledyne Brown Engineering (TBE). DESIS will be mounted on the International Space Station on the MUSES platform in 2018 and will provide hyperspectral Earth Observation in the wavelength range from visible to near-infrared with high resolution and near global coverage. TBE provides the platform and infrastructure on the ISS. DLR developed the instrument, while the optical system was fabricated and pre-aligned by the Fraunhofer Institut fur Angewandte Optik und Feinmechanik (IOF). This paper presents the on-ground adjustment, focusing and calibration approach for DESIS done at the optical lab of the Institut fur Optische Sensorsysteme (DLR). The optical lab set-up will be described in detail. Selected calibration results like detector Modulation Transfer Function (MTF) and linearity, optics MTF and wave front, focus position, smile and keystone measurement, instrument spatial and spectral MTF, and absolute radiometric calibration will be presented. The spectral and radiometric in- ight calibration approach of the DESIS calibration unit (CAL) based on stabilized Light Emitting Diode (LED) arrays will be demonstrated. In addition, the innovative pointing unit (POI) in front of the instrument and its pointing accuracy will be introduced. Finally imaging quality and accuracy of the sensor calibration will be evaluated with respect to foreseen applications.
The Institute of Optical Sensor Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center (DLR) has more than 30 years of experience with high-resolution imaging technology. This paper shows the institute’s scientific results of the leading-edge detector design in a BTDI (Bidirectional Time Delay and Integration) architecture. This project demonstrates an approved technological design for high or multi-spectral resolution spaceborne instruments. DLR OS and BAE Systems were driving the technology of new detectors and the FPA design for future projects, new manufacturing accuracy in order to keep pace with ambitious scientific and user requirements. Resulting from customer requirements and available technologies the current generation of space borne sensor systems is focusing on VIS/NIR high spectral resolution to meet the requirements on earth and planetary observation systems. The combination of large swath and high-spectral resolution with intelligent control applications and new focal plane concepts opens the door to new remote sensing and smart deep space instruments. The paper gives an overview of the detector development and verification program at DLR on detector module level and key parameters like SNR, linearity, spectral response, quantum efficiency, PRNU, DSNU and MTF.
We expect commercial high resolution imaging systems, which are able to provide data with 25cm ground sample distance (GSD) or better in the near future. For selling the data, it is necessary to re-sample it to 30cm. The situation is similar when swinging out the satellite perpendicular to his ight direction. The GSD is then variable with the angle to Nadir direction. In this paper a method is proposed that the resolution adjusts adaptively according to the requirements.
The Institute of Optical Sensor Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center
(DLR) has more than 30 years of experience with high-resolution imaging technology. This paper shows the institute’s
scientific results of the leading-edge detector design CMOS in a TDI (Time Delay and Integration) architecture. This
project includes the technological design of future high or multi-spectral resolution spaceborne instruments and the
possibility of higher integration. DLR OS and the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS) in
Duisburg were driving the technology of new detectors and the FPA design for future projects, new manufacturing
accuracy and on-chip processing capability in order to keep pace with the ambitious scientific and user requirements. In
combination with the engineering research, the current generation of space borne sensor systems is focusing on VIS/NIR
high spectral resolution to meet the requirements on earth and planetary observation systems. The combination of large-swath
and high-spectral resolution with intelligent synchronization control, fast-readout ADC (analog digital converter)
chains and new focal-plane concepts opens the door to new remote-sensing and smart deep-space instruments. The paper
gives an overview of the detector development status and verification program at DLR, as well as of new control
possibilities for CMOS-TDI detectors in synchronization control mode.
The facility Optical Information Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center (DLR) has more than 30 years of experience with high-resolution imaging technology. This paper shows the scientific results of the institute of leading edge instruments and focal plane designs for EnMAP VIS/NIR spectrograph. EnMAP (Environmental Mapping and Analysis Program) is one of the selected proposals for the national German Space Program. The EnMAP project includes the technological design of the hyper spectral space borne instrument and the algorithms development of the classification. The EnMAP project is a joint response of German Earth observation research institutions, value-added resellers and the German space industry like Kayser-Threde GmbH (KT) and others to the increasing demand on information about the status of our environment. The Geo Forschungs Zentrum (GFZ) Potsdam is the Principal Investigator of EnMAP. DLR OS and KT were driving the technology of new detectors and the FPA design for this project, new manufacturing accuracy and on-chip processing capability in order to keep pace with the ambitious scientific and user requirements. In combination with the engineering research, the current generations of space borne sensor systems are focusing on VIS/NIR high spectral resolution to meet the requirements on earth and planetary observation systems. The combination of large swath and high spectral resolution with intelligent synchronization control, fast-readout ADC chains and new focal-plane concepts open the door to new remote-sensing and smart deep space instruments. The paper gives an overview over the detector verification program at DLR on FPA level, new control possibilities for sCMOS detectors in global shutter mode and key parameters like PRNU, DSNU, MTF, SNR, Linearity, Spectral Response, Quantum Efficiency, Flatness and Radiation Tolerance will be discussed in detail.
At the German Aerospace Center (DLR), within the department Optical Information Systems, investigations are
currently being performed on time delay and integration charge coupled devices, with respect to their applicability on
satellites for earth observing missions. This paper contains first results of dynamic measurements of point spread
function and modulation transfer function of a sensor with 9000 pixels and 64 time delay integration steps. The influence
of a mismatch between the line synchronisation frequency and satellite ground speed, as well as the effect of angle
misalignment between satellite flight direction and the orientation of the sensor itself onto point spread function, and
modulation transfer function was investigated. The performance of the test equipment will also be presented.
Technology changes in detector development and the significant improvement of manufacturing accuracy in combination
with the permanent engineering research influences the spaceborne sensor systems, which are focused on Earth
observation and remote sensing. Developments in focal plane technology, e.g. the combination of large TDI lines,
intelligent synchronisation control, fast readable sensors and new focal plane and telescope concepts are the key
developments for new remote sensing instruments. This class of instruments disposes of high spatial and radiometric
resolution for the generation of data products for mapping and 3D GIS VR applications. Systemic approaches are
essential for the design of complex sensor systems based on dedicated tasks. The system-theoretical description of the
instrument inside and a simulated environment is the basic approach for the optimisation process of the optical,
mechanical and electrical designs and assembly. Single modules and the entire system have to be calibrated and verified.
The traceability of the performance-related parameters from the single sensor up to the flight readiness of the instrument
forms the main focus inside such complex systems. In the future it will also be possible to prove the sensor performance
on wafer level before assembly. This paper gives an overview about current technologies for performance measurements
on sensor, focal plane assembly (FPA) and instrument level without the optical performance of the telescope. The paper
proposes also a technology, which can be used for sensor performance measurements on wafer level.
Proc. SPIE. 6744, Sensors, Systems, and Next-Generation Satellites XI
KEYWORDS: Imaging systems, Sensors, Satellites, Remote sensing, Control systems, Charge-coupled devices, Microsoft Foundation Class Library, Modulation transfer functions, CCD image sensors, RGB color model
The department of Optical Information Systems (OS) at the Institute of Robotics and Mechatronics of the German Aerospace
Center (DLR) has more than 25 years experience with high-resolution imaging technology. The technology
changes in the development of detectors, as well as the significant change of the manufacturing accuracy in combination
with the engineering research define the next generation of spaceborne sensor systems focusing on Earth observation and
remote sensing. The combination of large TDI lines, intelligent synchronization control, fast-readable sensors and new
focal-plane concepts open the door to new remote-sensing instruments. This class of instruments is feasible for high-resolution
sensor systems regarding geometry and radiometry and their data products like 3D virtual reality. Systemic
approaches are essential for such designs of complex sensor systems for dedicated tasks. The system theory of the instrument
inside a simulated environment is the beginning of the optimization process for the optical, mechanical and
electrical designs. Single modules and the entire system have to be calibrated and verified. Suitable procedures must be
defined on component, module and system level for the assembly test and verification process. This kind of development
strategy allows the hardware-in-the-loop design. The paper gives an overview about the current activities at DLR in the
field of innovative sensor systems for photogrammetric and remote sensing purposes.
The Environmental Mapping and Analysis Program (EnMAP<sup>1,2</sup>) is a joint response of German Earth observation research institutions, value-adding (VA) resellers and space industry to the increasing demand on accurate, quantitative information about the evolution of terrestrial ecosystems. With its hyperspectral capabilities covering the visible, near- and short-wave infrared wavelengths, EnMAP will provide high quality, standardized, and consistent data on a timely and frequent basis. Its primary focus will be on the considerable improvement of already standardized products and the development of new quantitative and highly informative data and its derivatives. Only an imaging spectrometer, such as EnMAP, can resolve and detect biophysical, biochemical, and geochemical variables in distinct detail. This will tremendously increase our understanding of coupled biospheric and geospheric processes and thus, enable the management to ensure the sustainability of our vital resources.
After a successfully accomplished phase A, EnMAP has been approved by the German Aerospace Agency in the beginning of 2006. The instrument performance allows for a detailed monitoring, characterisation and parameter extraction of vegetation targets, rock/soils, and inland and coastal waters on a global scale. By the scientific lead of the GeoForschungsZentrum Potsdam (GFZ) and the industrial prime ship of Kayser-Threde, the ongoing planning aims towards an internationalisation of the mission approach.
The EnMAP instrument provides information based on 218 contiguous spectral bands in the wavelength range from 420 nm to 2450 nm. It is characterized by a SNR of > 500:1 in the VNIR and an SNR of >150:1 in the SWIR range at a ground resolution of 30 m x 30 m.
Recent developments in the fields of detectors on one hand and a significant change of national and international political and commercial constraints on the other hand led to a large number of proposals for spaceborne sensor systems focusing on Earth observation in the last months. Due to the commercial availability of TDI lines and fast readable CCD-Chips new sensor concepts are feasible for high resolution sensor systems regarding geometry and radiometry und their data products. Systemic approaches are essential for the design of complex sensor systems for dedicated tasks. Starting with system theory optically, mechanical and electrical components are designed and deployed. Single modules and the entire system have to be calibrated using suitable procedures. The paper gives an overview about current activities at German Aerospace Center on the field of innovative sensor systems for photogrammetry and remote sensing.
EnMAP (Environmental Mapping and Analysis Program) is one of the selected proposals for the national German Space Program. The EnMap project includes the technological design of the Hyperspectral Spaceborne Instrument and the algorithms development of the classification. EnMap will be developed to meet the requirements of the observation and investigation of ecosystem parameters for forestry, soil/geological environments and coastal zones/inland waters. It provides high-quality calibrated data and data products to be used as inputs for improved modelling and understanding of biospheric/geospheric processes, high-spectral resolution observations of biophysical, biochemical, and geochemical variables. This contribution describes some technological and theoretical aspects of the technical solution of the Hyperspectral Pushbroom Sensor working in the VNIR and SWIR spectral range. The Hyperspectral Pushbroom Imaging Spectrometer requires at least two different 2−dimensional detector array types, with one dimension for the spatial and the second dimension for the image information. The VNIR quantum detector will be sensitive from 420 nm up to 1030 nm and the SWIR detector from 950 nm up to 2450 nm. The VNIR modelling shows the difficulties of the SNR of the blue channels. Some measures will be discussed to improve this situation. The discussion will be lead to the requirements of the CCD, focal plane and to the data acquisition scenarios. The SWIR stability modelling gives an overview of the requirements to the detector and of some problems of the detector related system design.
During the last years the department of Optical Information Systems of the German Aerospace Center (DLR) developed a considerable number of imaging sensor systems for a wide field of applications.
Systems with a high geometric and radiometric resolution in dedicated spectral ranges of the electromagnetic spectrum were provided by developing and applying cutting edge technologies. Designed for photogrammetry and remote sensing, such systems play an important role for security and defence tasks. Complete system solutions were implemented considering theoretical framework, hardware design and deployment, overall system tests, calibration, sensor operation and data processing. Outstanding results were achieved with the airborne digital sensor ADS40 and the micro satellite BIRD and its infrared camera payload. Future activities will focus on intelligent cameras and sensor webs. The huge amount of data will force the issue of thematic multi-sensor data processing which is to be implemented in real time near the sensor. In dependence on well defined tasks, combinations of several sensors with special properties will be placed on spaceborne, airborne or terrestrial platforms. The paper gives an overview about finished and current projects and strategic goals.
The high-resolution imaging system ADS40 is a development to fulfill both photogrammetric and remote sensing requirements. The new sensor was introduced in mid 2000 and will close the digital chain for airborne photogrammetric data processing.
The Airborne Digital Sensor (ADS) a development to fulfil photogrammetric and remote sensing requirements. The new digital sensor is not only a camera for pretty nice pictures. It will be the next - full digital - generation as a measurement device for airborne photogrammetry and remote sensing. The high accuracy design of the focal plane system under flight and environmental conditions (pressure and temperature) will be presented. The ADS project will be introduced as a design of a modular customized CCD line scanner concept. It will be discussed on the ADS version with 4 multispectral CCD lines and 3 panchromatic CCD lines. The presentation will gives an overview of all dependencies and design constrains on the ADS Focal Pate Module (FPM). The ADS optical system has to support both photogrammetric accuracy and the requirement on the SNR for remote sensing applications. The principle to achieve good color pixel matching is described in relation to the customized CCD- and FPM- design. After a short description of the technical design and performances, some application examples are shown to demonstrate the main features of digital sensor: high accuracy, wide angle, high radiometric dynamics, high signal-to-noise-ratio, in-track stereo capability, multispectral capability.
Joint development work by DLR and LH Systems has produced a new camera concept called Airborne Digital Sensor which is using forward-, nadir- and backward-looking linear arrays on the focal plane. The camera system provides panchromatic and stereo information using three CCD lines and up to five more lines for multispectral imagery including two NIR channels. Each CCD array for panchromatic measurements has 24000 elements, resulting in a field of view of 64 degrees (across track FOV) by using a focal length of 62.5 mm. The sensitivity covers a dynamic range of 12 bit with a recording interval time of 1.2 ms per line. The performance of the camera allows a 3D and multispectral image with a ground sample distance of 25 cm for an area of 300 square miles within a flight time shorter than one hour.