This photodiode detector, the Extreme Ultraviolet Photodiode, has an aluminum film coating approximately 1500 Angstroms thick over the active area of the detector and is a phosphorus diffused (n on p) silicon photodiode. The photodiode wafer is fixed to a ceramic substrate and mounted to an aluminum mask. Near normal incidence solar photons enter an aperture stop that limits the field of view. A thin film filter is positioned directly behind the aperture, and its mount is slotted for atmospheric pumpout. A field stop mask with a circular cross section is placed directly in front of the coated wafer.