Large-area contrast of a fiber-optic coupled x-ray image intensifier

Large-area contrast measurements have been made upon a fiber-optic x-ray image intensifier with an external input phosphor. Both photometric and photographic techniques were used. For a shadowed area of 10% of the input window area, a contrast ratio in excess of 150 was determined. This is a factor of 5 higher than previously reported for any x-ray image intensifier. The improved contrast in the device is attributed to (1) reduced effect of x-ray Compton scattering in the input window; (2) less cross-chord light at the photocathode; and (3) greatly reduced light scattering and reflecting in output phosphor and window.