A lens coupled CCD camera showing single electron sensitivity has been built for TEM applications. The design is illustrated in Fig. 1. The bottom flange of a JEM-4000EX microscope is replaced by a special flange which carries a large rectangular leaded glass window, 22 mm thick. A 20 μm thick layer of red phosphor is coated on the window, and the entire window is sputter-coated with a thin layer of Au/Pt. A two-lens relay system is used to provide efficient coupling between the image on the phosphor scintillator and the CCD imager. An f1.0 lens (Goerz optical) with front focal length 71.6 mm is used as the collector. A mirror prism, of the Amici type, is used to "bend" the optical path by 90° to prevent X-rays which may penetrate the leaded glass from hitting the CCD detector. Images may be relayed directly to the camera (1:1) or demagnified by a factor of up to 3:1 by moving the lens assembly.
