Observation of microchannel plate multifibre structure in soft X-ray images

Abstract Flat-field images obtained during a microchannel plate X-ray detector calibration programme show low-contrast hexagonal structure correlated with multifibre boundaries within the microchannel matrix. In this letter, we show that these particular “chickenwire” patterns arise indirectly from a spatial variation of the detector gain and are not, as earlier hypothesised, the direct result of changes in channel open area, and, hence, in detector quantum efficiency, at the multifibre boundaries. Scanning electron micrographs of channel deformation at multifibre boundaries are presented. The use of a high-transmission mesh to collect photoelectrons from the interchannel web, while having no effect on the fixed-pattern noise, is shown, as predicted in an earlier paper, to be a significant source of image blur.