Entrance windows are used to protect the SDD sensor and maintain it in a controlled environment. In the soft X-ray region, below 1keV, the choice of window will significantly affect the transmission. Polymer windows (such as Moxtek AP3.3) provide improved low energy sensitivity compared to the thicker and more robust Beryllium windows.
Polymer light element windows require a support grid which limits transmission to the open area fraction (typically 80%) at higher energies.
Sensor area is a factor which influences the window choice. As larger areas are required, the window must be thicker in order to support the differential pressure.
For the ultimate low energy performance, RaySpec can offer detectors with windowless sensors and incorporate gate valves and bellows as required into the design.