Nucleation-film/Electron-beam recorder: Near-real-time display system

A direct electron-beam recorder (EBR) for nucleation film has been built and tested. This recorder overcomes many of the disadvantages of CRT-on-film recorders by providing a high-resolution black-on-white image that is available for viewing 1 s after recording. Immediate viewing of the film record eliminates the need for a CRT display with storage for viewing images from line-scan reconnaissance sensors. Nucleation film is developed by the selective condensation of zinc vapor on nucleation sites produced by electron exposure. It is developed in vacuum, adjacent to the recording electron beam. The image has a contrast of 8:1 for an exposure of 2 × 10¹¹electrons/cm². This EBR display uses 70-mm film at speeds of 0.08 to 8.3 cm/s to record a video image from a line-scan reconnaissance sensor. This contrasts with a previously described nucleation film/EBR that recorded high-resolution television images at 60 fields/s on 35-mm-wide film transported at 43 cm/s. The present recorder/display has an image viewing area 6 cm wide by 22 cm high where the 70-mm-wide film moves from top to bottom. The video bandwidth is 5 MHz and the horizontal resolution is 2400 lines. A major accomplishment of the work reported here was the design of a zinc vapor source with uniform flux for development of the 70-mm-wide nucleation film in a 0.5-cm space adjacent to the recording electron beam.