Pretty much answered by the original question: > Why aren't these more common? There's no economies of scale. Looking at the ad for these in https://www.lumi

Pretty much answered by the original question: > Why aren't these more common? There's no economies of scale. Looking at the ad for these in https://www.lumineq.com/technology https://www.lumineq.com/technology: "TFEL technology has proven its excellence in applications ranging from monitor and control instruments in deep-sea vessels to operational systems in orbital spacecraft."