Optical design of diffraction-limited x-ray telescopes.

Area of Science:

• Astronomy and Astrophysics
• X-ray Optics
• Telescope Design

Background:

• Micro-arcsecond (µas) angular resolution in astronomical imaging promises significant scientific breakthroughs.
• Existing µas x-ray imager designs, primarily interferometers, suffer from limited effective collecting areas.

Purpose of the Study:

• To describe novel x-ray telescope designs capable of diffraction-limited performance with large effective areas.
• To present compact nested-shell Wolter Type 2 grazing-incidence telescope designs for high-resolution x-ray imaging.

Main Methods:

• Utilizing a nested-shell architecture with grazing-incidence mirrors to achieve diffraction-limited imaging.
• Matching optical path lengths between all mirror shells to minimize aberrations.
• Investigating and mitigating chromatic and off-axis aberrations through path length adjustments.

Main Results:

• A micro-arcsecond telescope design with 14 µas resolution and 2.9 m² effective area at 5 keV.
• A milli-arcsecond telescope design with 525 µas resolution and 645 cm² effective area at 1 keV.
• Demonstrated mitigation of chromatic aberration and identified field curvature as the primary off-axis aberration.

Conclusions:

• The proposed telescope designs present a viable path towards achieving diffraction-limited x-ray imaging.
• While demanding, the required mirror surface and alignment tolerances are considered achievable in the future.
• A 1 arc second field of view is feasible with a flat detector, despite formation flying requirements.