The thin-layer plate is exposed to the phosphor imaging plate by direct contact in a sandwich configuration. The phosphor accumulates and stores energy from the decay of radioisotopes as a latent image. Subsequently, the stored energy within the phosphor is released by stimulation with visible light to produce a luminescence signal measured by a photo-multiplier tube. The phosphor imaging plate is scanned with a laserbeam in a dedicated instrument called a phosphorimager, for this purpose. In this way, the creation of an image of the chromatogram containing location and intensity information is obtained in a two-step process.