A high-gain screen can be made as a sandwich of a hologram and a retroreflective screen material. When a hologram is used in front of the screen instead of the screen material alone, the position of high-brightness viewing can be moved to any desired angle rather than being directed back along the projection beam.

We revisit the doubly-layered sandwich detector con guration for single-shot dual-energy x-ray imaging. In order to understand its proper operation, we investigated the contrast-to-noise performance in terms of the x-ray beam setup using the Monte Carlo methods. Using a pair of active photodiode arrays coupled to phosphor screens, we have built a sandwich detector. For better spectral separatio...