The abbreviation “eXTP” represents the enhanced x-ray timing and polarimetry, which is a key science mission initiated by the Chinese scientists, designed to study the state of matter under extreme conditions of density, gravity and magnetism [1]. Various payloads would be on board of the satellite. The SFA, namely the spectroscopy focusing array, consisting of nine identical x-ray telescopes working in the energy range of 0.5-10 keV, will be the focus here [1]. SFA has a field-of-view of 12 arcmin for each and a collecting area of 900 cm² and 550 cm² for each at 2 keV and 6 keV respectively [1].

This paper starts with a brief introduction of the general optics, and then goes across some important design aspects. It covers contents from the structural and thermal designs to the CAE analyses as well as the current status. The large diameter and huge focal length of the optics will definitely bring big issues to the robustness of the carrying structure under the severe conditions given by the launcher.

According to the current design, the mirror assembly will have 3 feet and 24 spokes. Vibration tests were already performed on a few prototypes by IHEP, and a preliminary evaluation on the feasibility of the design has been achieved. It clearly stated that the current design with only a single spider can probably survive the vibration tests assuming a compromised test condition somewhere. CAE models were adjusted thereafter to match the test results, which could be used for further assessments in a near future.

Future high energy astrophysics missions will require high performance novel X-ray optics to explore the Universe beyond the limits of the currently operating Chandra and Newton observatories. Innovative optics technologies are therefore being developed and matured by the European Space Agency (ESA) in collaboration with research institutions and industry, enabling leading-edge future science missions.

Silicon Pore Optics (SPO) [1 to 21] and Slumped Glass Optics (SGO) [22 to 29] are lightweight high performance X-ray optics technologies being developed in Europe, driven by applications in observatory class high energy astrophysics missions, aiming at angular resolutions of 5” and providing effective areas of one or more square meters at a few keV.

This paper reports on the development activities led by ESA, and the status of the SPO and SGO technologies, including progress on high performance multilayer reflective coatings [30 to 35]. In addition, the progress with the X-ray test facilities and associated beam-lines is discussed [36].