This striking derailleur is a derivative of a Sachs Quartz branded as Stronglight. Stronglight called this model 'Rockstrong'.
As the French bicycle component industry fell apart in the 1990’s both the Stronglight brand and the old Sachs (and before that Huret) factory ended up owned by the same company - called IRCOS. I think this derailleur is one of the results of this benighted coming together.
None of this is terribly exciting - but what is exciting is the fantastically French colour scheme of this prototype (unfortunately this colour scheme never made it into production). Yes, the blue does glow like that, and yes, those red pulley wheels are original. You can’t look at it without thinking that le jour de gloire est arrivée.