Distortion-Free Microchannel Plate Mercury Atomic Resonance Ionization Image Detector

Abstract

An atomic mercury resonance image detector with microchannel plate amplification and charge-coupled device (CCD) detection is evaluated. A thin Pt film on the surface of the input window of the resonance ionization image detector (RIID) eliminated the surface charge on the input window. Image spatial resolution of better than 120 μm was achieved. The linearity of the image intensity vs. imaging signal energy is currently limited by the linearity of the CCD. In addition, the image quality (spatial resolution and dynamic range) is improved by using a microchannel plate (MCP) in front of the input window of the RIID. The RIID has a much improved contrast ratio. Several noises, including multiphoton photoionization noise, noise due to parasitic luminescence of the phospher screen, and MCP noise, were minimized. The main noise source was the photoelectric effect of the metal input electrode of the CCD when illuminated by 254 nm radiation.