Texture analysis of phosphor screens

Describes a method using the optical Fourier transform to test cathodo- and photoluminescent screens. The transmittance spectrum is obtained and studied. Screen texture can be either uniform or clustered. From results on cathodoluminescent electrophoretic screens good performance of uniformly textured screens is related to a monotonically decreasing spectrum in the spatial frequency domain. Screens showing grain clusters can be easily identified during manufacture by their Fourier spectrum instead of by microscope observation. The consequences of a clustered structure in screens operating either by electron or X-ray excitation are briefly discussed. When the average cluster dimension must belong to a determined range the optical Fourier transform enables an automatic sorting system to be implemented.