The ESA EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key spatial context providing instrument within the payload suite of 4 instruments is the Multi- Spectral Imager (MSI). This paper discusses the test program developed and implemented at SSTL for the formal qualification of the COTS micro-bolometer detectors for the TIR camera of the MSI. The comprehensive test campaign for the qualification of the detectors covered full electro-optical characterisation, life tests, environmental testing (thermal and mechanical), Particle Impact Noise Detection (PIND) tests, destructive physical analysis (DPA) and radiation tolerance assessment. Testing was undertaken at the specialist detector test facilities at SSTL. External facilities were called on for aspects of the programme. We describe the microbolometer arrays tested, the test benches developed for the program, test facilities, the test procedures and a summary of the test results. The qualification programme was completed in May 2014.
The EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key
spatial context providing instrument within the payload suite of 4 instruments is the Multi-Spectral Imager (MSI).The
MSI will take data at 500m ground sample distance (GSD) over a swath width of 150 km via pushbroom imaging. One
part of the MSI instrument will be a thermal IR optical unit (TIROU). We describe the design of the focal plane array for
the TIROU, its time-delay and integration readout scheme and present results derived from its associated simulator.
A test programme for infrared detectors in support of the EarthCARE mission is discussed. Commercially available
linear InGaAs arrays from XenICs, Belgium (cut-off wavelengths 1.7, 2.2 and 2.5 μm), 384 x 288 amorphous silicon
microbolometer arrays from ULIS, France and un-windowed single element lithium tantalate pyroelectric detectors from
Infratec, Germany have been studied in detail to assess their suitability for EarthCARE and to provide performance data
to aid in the design of the flight instruments. Tests included radiation resistance (cobalt60 and 60 MeV protons plus a
heavy ion latch-up test for the InGaAs and microbolometer arrays), dark signal, noise, output stability, linearity,
crosstalk and spectral response. In addition, the pyroelectric detectors were tested for low microphony.
The development and application of a three-dimensional finite-difference time-domain (FDTD) model for a traveling-wave heterojunction phototransistor (TW-HPT) are presented. The model is enhanced using effective permittivity schemes at the dielectric interfaces and special techniques for the treatment of very thin material sheets. The 3D full-wave electgromagnetic model allows the numerical calculation of the output photocurrent, electrical characteristic impedance, light absorption, microwave losses as well as microwave and optical dispersion. Run in a fast, parallel processing, machine the simulation herein allowed (for the first time, to the best of the authors' knowledge) the simultaneous investigation of the optical and microwave characteristics of the traveling-wave structure. This is in contrast to the approach followed by other researchers in the past, as well as by popular simulation packages, based on which results only for the microwave property can be obtained. Snapshots of the field propagation inside the device provide valuable insight into its passive behavior and clearly demonstrate the device's velocity mismatch between the optical signal and the photogenerated electrical pulse. Numerical results for the effective refractive indices of the optical and electrical wave quantify the difference in the velocities of the two waves.