The PLATO detectors are CCDs provided by e2v, model CCD270, specifically developed for this mission. They are built with two separately connected sections to allow full frame (FF) or frame transfer (FT) readout modes. They are back-illuminated, back-thinned devices, non-inverted type (cf. CCD characteristics).
An antireflection coating on its sensitive surface provides for the highest quantum efficiency over a broad wavelength range. Only one readout register with two outputs is required for both the FF and FT devices. The detectors will work at a temperature lower than –65°C to minimise dark current and radiation damage.
Each Focal Plane Assembly structure supports 4 CCDs via quasi-static mount on a support plate, ensuring a very good planarity. The support plate is made in Titanium, attached to the telescope structure by 3 bipods, also in Titanium. It has the possibility to be adjusted in position (along the optical axis and around the camera transverse axes) by using 3 shims located at the interface between the FPA bipods and the telescope structure. It is electrically isolated from the telescope, and the thermal power dissipated at FPA level is evacuated to the telescope structure by means of 3 flexible thermal straps thermally connected to the CCD packages.
The flexi-cables connecting each CCD to the FEE have a free length of ~ 80 mm from the bottom of the FPA to the top of the FEE. The distance between FPA and FEE is limited to a nominal value of 65 mm to get slightly bended flexi-cables allowing small misalignments, displacements or rotations between them during AIT, and launch.
Extensive analysis has been performed to guarantee the PLATO FPA performances in terms of vibration robustness, flatness, CCD temperature, while remaining within mass and power budget. Finally, integration and verification procedures for the FPA have been defined and tested using a mock-up manufactured in Al.
The Focal Plane Array is under responsibility of Spain.
PLATO – Revealing habitable worlds around solar-like stars
Definition Study Report, ESA-SCI(2017)1, April 2017