is scanned across an image of the scene to be broadcast focused on a target. This generated a current that is dependent on the brightness of the image on the target at the scan point. The size of the striking ray is tiny compared to the size of the target, allowing 480-486 horizontal scan lines per image in the NTSC format, 576 lines in PAL, and as many as 1035 lines in Hi-Vision.

Cathode-ray tube