Two general techniques may be used for whole image detection by electronic means in the extreme ultraviolet (XUV). 1) The XUV image is converted to a visible image for further processing, and 2) the XUV image is detected via the photoelectrons it ejects from a photocathode. The first technique involves the use of a phosphor either as a conversion layer to be excited directly by the XUV photons, or as a luminescent detector of photoelectrons created by the XUV photons. The second technique may require that the number of photoelectrons be amplified while preserving the same spatial coordinates as the impinging XUV protons. After amplification, the spatial coordinates of the amplified photoelectrons can be determined using different electronic techniques. Alternatively the second technique makes use of electronic imaging systems wherein the photoelectrons created by an XUV image on a photocathode are focussed onto nuclear track emulsion to form a photographic record of the image. Representative examples of each type of imaging system will be discussed.
W. R. Hunter, W. R. Hunter,
"Electronic Imaging In The Extreme Ultraviolet Spectral Region", Proc. SPIE 0143, Applications of Electronic Imaging Systems, (15 September 1978); doi: 10.1117/12.956553; https://doi.org/10.1117/12.956553