Which layer in the phosphor layer setup affects image resolution in an image intensifier?

In an image intensifier, the layer that most significantly affects image resolution is the thickness of the phosphor layer. The phosphor layer is responsible for converting incoming X-rays into visible light, and its thickness directly influences the sharpness and clarity of the resulting image. A thinner phosphor layer typically allows for better resolution because it reduces the scattering of light; the less light that scatters, the sharper the image that is produced.

When the phosphor layer is thicker, there is an increased likelihood of light photons diffusing before they reach the photocathode. This diffusion can lead to blurred images, as the precise location of the original X-ray event becomes less defined. Thus, controlling the thickness of this layer is critical in optimizing image quality, especially in applications where high detail is necessary for accurate diagnosis or procedural guidance.

Other layers, such as the aluminum base layer and the photocathode layer, play significant roles in the overall function of the image intensifier, but they do not directly impact the resolution to the same extent that the phosphor layer thickness does. The intermediate coupling layer serves to transfer the light produced by the phosphor layer to the photocathode but does not influence the resolution itself.