This is a microchannel plate array from an interim version of the X-ray detector intended for the Advanced X-ray Astrophysics Facilty (AXAF). The Einstein X-ray telescope satellite (HEAO-2), launched in 1978, was the first to be equipped with a high resolution imager (HRI) to visualize the structure of astronomical X-sources. The overall detector included this microchannel plate backed by a cross-grid detector. The plate converted incident X-ray photons to electrons and amplified them by orders of magnitude. The signal was picked up by the cross grid detector and its strength and location used to build an image of the source. The X-Ray Astronomy group at the Smithsonian Astrophysical Observatory designed and built this scaled-up version of the HRI on the way to building the imager that was installed on the final version of the AXAF which was named Chandra just before its launch. This microchannel plate is a model closely related to those used in military night vision devices. SAO transferred it to NASM in 2002.