II output to TV optical coupling and image distributor
The small bright image-intensifier output phosphor sits at the focal plane of a primary (collimating) lens, producing a parallel light beam. In this collimated region between the lenses are a variable circular iris (light proportional to aperture diameter squared), a semi-transparent beam-splitting mirror that diverts part of the light to a cine/photospot camera on a second port, and an electronic light sensor for automatic brightness control. A secondary relay/TV lens then focuses the beam onto the TV/CCD sensor. Some light is lost at the coupling; fibre-optic coupling is an alternative.
Practice the Physics paper
FRCRX is a Part 1 Physics question bank: true/false items with explanations, timed mocks and topic analytics.