The optical laboratories are dedicated to optical calibration, verification and validation tasks in the spectral, radiometric and geometric domain. The focus is on high-resolution spatial, radiometric and spectral systems. In addition to complete systems also subsystems such as focal plane units and single optical components (e.g. transmitting / reflective optics) are characterized. Optical systems are examined in the whole spectral range from Ultraviolet (UV) to the Thermal infrared (TIR). The optical laboratories are located in an ISO 8 clean room. The usage of a localized ISO 5 clean room condition is possible.
The main objective is the radiometric and geometric calibration of optical sensors. The measured parameters (e.g. Signale Nois Ratio (SNR) and Modulation Transfer Function (MTF)) provide information on the image quality of the sensor. The radiometric calibration allows the conversion of digital values of the optical system into physical units of radiance. By means of the geometric calibration the viewing angle in the object space is determined for each pixel. The equipment, the measurement setups and the employed methods allow a traceable calibration.
The optical laboratories consist of three parts: geometric laboratories, radiometric laboratories and spectral laboratories. The following equipment is available:
Mehrere Ulbricht Kugeln (inkl. photometrischer Überwachung, thermostatische Einrichtung)
Several integrating spheres (incl. photometric monitoring, thermostatic set up)
Several Lambertian radiators (Spectralon, Barium sulfide, matted quartz halogen filament)
Blackbody IR Light Sources with 1” and 4” aperture, temperature up to 1470°C
UV/VIS/NIR spectrometer Lambda 950S (spectral range 0.19 – 3.3 µm)
Two gimbal mounts and hexapods for instruments under test (2 rotational, 3 translational degrees of freedom)
Theodolites and levelling laser
Mirror collimator (off-axis paraboloid, 1200/8, spectral range 0.23 to 15 µm)
Lens collimator (1200/8)
VIS/NIR monochromator (spectral range 0.35 – 2.5 µm)
VIS/IR monochromator (spectral range: 0.4 to 15 µm)
Calibrated reference detectors for VIS/IR
MTF test bench for transmittive optical equipment (VIS to LW-IR, finite, infinite, afocal)
IR test bench
Gimbal-Mount for instrument under test (2 rot)
Collimator (f = 1778 mm)
The laboratories are also used for optical alignment and integration of space instruments and components. Additionally, a small transportable thermal vacuum chamber is available. The optical equipment in this room allows the calibration of instruments for deep space missions (e.g. MERTIS, CHEOPS).
During last years the geometric calibration was extended by dynamic geometric measurement configurations. So, the laboratories support a dynamic scene generation: For VIS wavelengths a sophisticated measuring station was build for characterization of high-speed Time delay integration (TDI)- sensors. A special testbench is used for the characterization of dynamic effects of Infrared detectors.
