Recently the mechanical parts for the spot-on test setup have arrived at Lens R&D. Under construction in frame of an ESA GSTP program to produce and quality extended temperature sunsensors, the setup is intended to allow temperature coefficient determination of 12 sunsensors simultaneously.
Because the temperature coefficient will have to be determined over a temperature range of -125°C to +125°C, this can only be done in vacuum while conductively cooling the sensors. A correct measurement however also entails using at least one reference sensor which is kept at room temperature throughout the process. Last but not least, the tests will be performed at the MiVaF facility at ESTEC which uses an arc discharge lamp to generate the sun illumination signal and consequently produces a lot of 100Hz flicker. These requirements have led to the construction of a dedicated setup.
The effect of the flicker will be minimised by using dedicated simultaneous sampling electronics which will allow to readout all 56 photodiode and 14 thermistor signals within a fraction of a microsecond.
The unique setup will provide more insights into the quality of the ESA setup (temporal and spatial flicker noise) and will allow to optimise the calibration strategy to be followed if multiple sensors are to be calibrated for use as a coarse sunsensor. (taking all four generated currents together thus providing a single measurement value per sensor).
Although never intended to be used as a coarse sunsensor, this mode of operation of the BiSon sunsensors is expected to give a higher accuracy than a single photodiode although with a slightly reduced field of view. Measuring 12 sensors at the same time will allow for a cost effective determination of the temperature coefficient which is needed to operate the sensors outside of the fine sunsensor mode and the simultaneous sampling will avoid long measurement times needed to take several thousands of measurements to average out the source flicker.
Another significant investment performed to get ahead of our competition in providing cost effective solutions for high reliability Sun sensing.