Application of Photolithography to Development of Photocathodes for Electron Optical Imaging Devices

Photolithography was used for the replication of high resolution patterns from flat master masks to curved quartz substrates. Special Mylar photomasks were developed for contact printing of the patterns on the curved substrates, The contrast of the Chromium-Gold mask on Mylar was determined by micro-densitometry. This was followed by the deposition of thin films of gold on the patterned surface to obtain the photocathodes.This paper describes the methodology of the experimental techniques employed for such photocathode processing. The most important use of patterned gold photocathodes is in studying the electron-optical characteristics of high resolution electron devices like image tubes. A brief description of such studies carried out on an electron-optical bench is given.