The main aim of the activity is to develop and test large area optical filters for future soft X-ray instrumentation.

Future X-ray astronomy missions have identified a need for large area, optical filters with very high transmission in the soft X-ray portion of the electromagnetic spectrum. The filters require a diameter of order of 130 mm or larger, must be pin-hole free and with visible light attenuation of several orders of magnitude, while operating at cryogenic temperature.The objectives of the activity are to design, manufacture and characterise filters that meet the instrument requirements and to demonstrate a production process with a yield high enough to satisfy future mission development schedules.