Page "Image intensifier" Paragraph 9

A photographic comparison between a first generation cascade tube and a second generation wafer tube, both using electrostatic inversion, a 25mm photocathode of the same material and the same F2. 2 55mm lens.

The first generation cascade tube exhibits pincushion distortion while the second generation tube is distortion corrected.

All inverter type tubes, including third generation versions, suffer some distortion.