1. A pattern of electric charges on an insulating plate, with the magnitude of the charge at each point being proportional to the brightness of the corresponding point in an optical image.
2. A representation of an object formed by a beam of electrons focused by an electron optical system.
3. An image formed in a stream of electrons.

The electron density in a cross section of the stream is at each point proportional to the brightness of the corresponding point in an optical image.

1. A tool which projects an optical image generated by electromagnetic radiation from a photosensitive surface onto a fluorescent screen.
2. An electron tube which reproduces on its fluorescent screen an image of the optical image or other irradiation pattern arriving at or striking its photosensitive surface.
3. A cathode-ray tube that has a photoemissive mosaic upon which an optical image is projected, and an electron gun to scan the mosaic and to convert the optical image into a corresponding electrical current.