A figure of merit for the assessment of image intensifier systems

Abstract A dimensionless figure of merit (F), which combines key aspects of the performance of image intensifier systems, is derived. This figure is ideally independent of input air kerma rate and field size and relates to the fundamental characteristics of the image reception chain. In practice it is calculated from measurements of the threshold contrast (noise) and limiting resolution using the Leeds test objects and the input air kerma rate. Several practical examples illustrate its usefulness in simple performance assessment and quality assurance procedures. A comparison is made with the use of detection index diagrams.