A concept for the X-ray telescope system with an angular-resolution booster

TL;DR

This paper proposes a novel X-ray telescope system that combines a slightly out-of-focus detector setup with multi-grid masks to significantly enhance angular resolution while maintaining high throughput, suitable for high-energy astronomy.

Contribution

It introduces a new concept of using coded aperture masks with a focusing mirror to boost angular resolution beyond conventional limits in X-ray telescopes.

Findings

Achieves 4" and 0.4" angular resolution at 7 keV with specific mask separations.

Maintains high effective area and throughput in the proposed design.

Potential to reach diffraction-limited resolution in high-energy X-ray observations.

Abstract

We present a concept of the X-ray imaging system with high angular-resolution and moderate sensitivity. In this concept, a two-dimensional detector, i.e., imager, is put at a slightly out-of-focused position of the focusing mirror, rather than just at the mirror focus as in the standard optics, to capture the miniature image of objects. In addition, a set of multi-grid masks (or a modulation collimator) is installed in front of the telescope. We find that the masks work as a coded aperture camera and that they boost the angular resolution of the focusing optics. The major advantage of this concept is that a much better angular resolution an order of 2--3 or more than in the conventional optics is achievable, while a high throughput (large effective area) is maintained, which is crucial in photon-limited high-energy astronomy, because any type of mirrors, including light-weight reflective mirrors, can be employed in our concept. If the signal-to-noise ratio is sufficiently high, we estimate that angular resolutions at the diffraction limit of 4" and 0"4 at about 7 keV can be achieved with a pair of masks at separations of 1~m and 100~m, respectively, at the diffraction limit.