Predicting micropore optic performance based on pore wall surface measurements

Le résumé fourni par la source

Micropore optics (MPOs) are a style of grazing incidence optics used in astrophysics and heliophysics applications for imaging X-rays over a large field of view. They are composed of an array of high aspect ratio square channels tens of microns in width, which are then slumped into a spherical curvature. This unusual geometry makes predicting their performance as optical components challenging. The point spread function (PSF) of an ideal MPO is well understood, but the way in which manufacturing defects and inconsistencies such as surface roughness contribute to overall image quality is not well known. In this work, a laser confocal microscope is used to measure the surface profiles of the pores of two modern MPOs from different manufacturers, with measurement methodology presented in detail. A mathematical model is developed to calculate realistic geometric optics-based angle perturbations from these real surface profiles, which modify the trajectory of photons in a Monte Carlo ray tracing simulation. This model is then used to predict the performance of MPOs based on their surface profiles. The full width at half maximum (FWHM) values of the simulated PSFs of these optics are compared with the actual FWHM of the two optics as determined experimentally through incident photons. The experimentally measured FWHM values are similar to, but slightly lower than, what the model predicts. One explanation for this is that the surface quality of pores on the exterior of an MPO may be degraded relative to the majority of pores on the interior. Measurements of the interior and exterior pores of a diced optic provide support for this explanation. Based on the collected data, the slope distributions of profiles in an optic’s pores are good metrics for predicting image quality.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.