Howard Winter wrote:

>  I'm not sure how they managed to get photosensitive valves 
> ("tubes") to read in the space available - 
 > I assume there was some sort of light pipe, but this predated fibre optics of
> course.

Lucite (clear plastic) pipes that were heat formed to fan out from the reader
head to a cluster of phototubes. The pipes yellowed with age requiring the
light level to be adjusted upward over time.

Robert
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