150 mm Image Intensifier

Photek have built a prototype 150 mm diameter zoom image intensifier believed to be the biggest visible light image intensifier ever made. The bialkali photocathode is formed on the curved inside surface of a fibre optic plate that is flat on the outside surface to enable super efficient optical coupling to, for example, an X-Ray scintillator screen or to arrays of scintillating fibre optic.

The photo electrons from the photocathode are focused onto the input surface of a 40 mm microchannel plate electron multiplier and phosphor screen assembly. Consequently each input photon over the entire 150 mm input surface produces, on average, 1 million visible photons that can subsequently be mapped onto a CCD camera. Each input photon is therefore amplified to an extent that the signal induced in the CCD is well above the noise even in uncooled, fast frame, rate cameras. Photon counting digital techniques can be used to enhance the resolution and signal to noise ratio of the subsequent image.

The new tube is expected to be used in nuclear particle physics, X-Ray crystallography and many other applications where light collection efficiency from large objects is at a premium.