Imaging of large-area microchannel plates using phosphor screens

A testing system was built, using UV illumination at 254 nm and a cathodoluminescent phosphor screen, to measure the gain uniformity of large area (20 × 20 cm²) microchannel plates. The phosphor screen image is captured with a wide-angle CMOS digital camera (4032 × 3024 pixels) and analyzed. First a reference MCP is illuminated and the generated phosphor screen image is captured with a CCD camera. In a second step, another image is captured with the MCP under test inserted between the reference MCP and the phosphor screen. The ratio of the two images is analyzed and provides a quantitative measure of the relative gain uniformity of the MCP under test