HEW simulations and quantification of the microroughness requirements for X-ray telescopes by means of numerical and analytical methods

TL;DR

This paper evaluates how microroughness affects X-ray telescope imaging quality across different energies using numerical and analytical methods, focusing on the SIMBOL-X telescope's performance.

Contribution

It introduces a combined numerical and analytical approach to quantify microroughness effects on HEW in X-ray telescopes, including figure errors.

Findings

Both methods provide consistent HEW estimates across energies.

Microroughness significantly impacts HEW at higher photon energies.

The approach aids in defining surface quality requirements for future telescopes.

Abstract

Future X-ray telescopes like SIMBOL-X will operate in a wide band of the X-ray spectrum (from 0.1 to 80 keV); these telescopes will extend the optical performances of the existing soft X-ray telescopes to the hard X-ray band, and in particular they will be characterized by a angular resolution (conveniently expressed in terms of HEW, Half-Energy- Width) less than 20 arcsec. However, it is well known that the microroughness of the reflecting surfaces of the optics causes the scattering of X-rays. As a consequence, the imaging quality can be severely degraded. Moreover, the X-ray scattering can be the dominant problem in hard X-rays because its relevance is an increasing function of the photon energy. In this work we consistently apply a numerical method and an analytical one to evaluate the X-ray scattering impact on the HEW of an X-ray optic, as a function of the photon energy: both methods can also include the effects of figure errors in determining the final HEW. A comparison of the results obtained with the two methods for the particular case of the SIMBOL-X X-ray telescope will be presented.