Infographics / Fluoroscopy

Output phosphor characteristics

Cross-section of an image intensifier output screen. The large accelerated electron image converges onto a small output stack made of a thin aluminium backing, a thin silver-activated zinc cadmium sulphide (ZnCdS:Ag) phosphor and a thick glass output window. The phosphor converts electrons to green light, which passes forward through the glass and optical coupling to the camera; the aluminium backing blocks light returning to the photocathode.

Image intensifier output screen (cross-section) Cross-section of an image intensifier output screen. The large accelerated electron image converges onto a small output stack made of a thin aluminium backing, a thin silver-activated zinc cadmium sulphide (ZnCdS:Ag) phosphor and a thick glass output window. The phosphor converts electrons to green light, which passes forward through the glass and optical coupling to the camera; the aluminium backing blocks light returning to the photocathode. Image intensifier output screen — cross-section from photocathode side accelerated, focused electrons green light optical coupling camera (TV / CCD) aluminium backing ZnCdS:Ag phosphor (thin, a few µm) thick output glass window output screen ø 25–35 mm Anode (+25 to +35 kV) accelerates electrons onto the phosphor → light (scintillation). Phosphor: ZnCdS:Ag, thin (few µm), green (~520–560 nm); small ø → minification gain ≈ (D_in/D_out)². Aluminium backing reflects light forward and blocks feedback to the photocathode (veiling glare). Thick glass window limits electron backscatter (halo); output is bright enough to view / record.
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