The Advanced X-ray Astrophysics Facility (AXAF) is a major NASA space observatory (launch 1998). One of its two focal plane detectors is the High Resolution Camera (HRC) assembly consisting of two microchannel plate (MCP) based detectors. Key components of the two HRC detectors are UV/Ion shields consisting of metalized sub-micron plastic membranes, designed to prevent UV light and positive ions from reaching the detectors' sensitive surfaces. We discuss the design issues and present results of recent measurements and tests. Soft X-ray/UV transmission measurements have been conducted at the Space Science Laboratory (SSL), University of California at Berkeley, and at the Osservatorio Astronomico di Palermo G.S. Vaiana, Italy, on sample films of different plastic materials under study, namely Lexan, Polyimide, Parylene-C, and VYNS. Acoustic tests of baseline design UV/Ion shields' samples have been conducted at the Marshall Space Flight Center (MSFC). Computer simulations have been conducted to estimate the HRC count rate due to diffuse UV background and Hot stars.