g. ESA Sentinels II and III [7], the evaluated Explorers FLEX (Fluorescent Explorer) [8] and TRAQ (Tropospheric Composition and Air Quality) [9], the German national initiative ENMAP (Advanced Hyperspectral Mission) [10], and the South African MSMI (Multi Sensor Micro satellite Imager) [11] among others.2.?Sensor overviewThe APEX instrument consists of several sub-units (Figure leave a message 1). The optical sub-unit (OSU) is the Inhibitors,Modulators,Libraries core element of the instrument including the sensitive optics, properly interfaced with customized front-end Inhibitors,Modulators,Libraries electronic (FEE) boards. The OSU is operated on a stabilized platform (STP) in order to dampen all the externally induced vibrations and ensure stable vertical measurements.
The platform is controlled by the navigation system, which receives orientation information from an inertial measurement unit (IMU) implemented on the OSU and position signals from a GPS receiver.
The orientation and position information are Inhibitors,Modulators,Libraries then synchronized with the image data Inhibitors,Modulators,Libraries by the control and storage unit (CSU). Each data frame is thus time and day tagged and stored on a hard disk array. This information is finally transferred to the processing Inhibitors,Modulators,Libraries and archiving facility (PAF), either over a Gigabit Ethernet or via storage tapes.Figure 1.Overview APEX subsystems.The instrument is temperature and pressure stabilized. The opto-mechnical unit (OMU) is enclosed by the environmental thermal control box (ETC). The thermal control unit (TCU) controls the temperature of the OMU cooling circuits and of the ETC box atmosphere.
The SWIR (Short Wavelength) detector is directly linked with a dedicated cooling system that keeps its temperature at about -100 ��C, thus drastically reducing the thermal noise. The main units are illustrated in Figure 1.A custom aircraft Drug_discovery interface (A/C-I/F) allows the Dornier Do-228 Inhibitors,Modulators,Libraries airplane to carry and operate the instrument during the mission phases.A detailed representation of the optical subunit (OSU) is given in Figure 2. This subsystem is composed of the following elements (see Figure 2):An entrance window, located underneath the folding mirror.One folding mirror, guiding the entering light towards the ground imager.A removable polarization scrambler that reduces the polarization sensitivity of the instrument.
A filter wheel, containing a series of neutral density filters in order to avoid saturation and a series of bandpass filters Inhibitors,Modulators,Libraries used in connection with the in-flight calibration facility (IFC).A ground imager that images the ground inhibitor supplier section on the spectrometer rectangular slit, whose dimensions are 0.04 mm �� 40 mm.A spectrometer section that decomposes the incoming light into its spectral components and re-images the slit image onto two array detectors.Figure 2.Main elements of the Optical Unit System of Cilengitide now the APEX sensor.