Not to create further controversy, but yes, Voigtländer as an independent company died when they were merged with Zeiss a long time ago. Braunschweig kept up for a while within ZIV, but when the combined efforts had to give up in the face of Japanese competition, the Voigtländer name was sold on. As far as I have been able to ascertain, the copyright is held by Ringfoto. If you want the original, go to the collectors market.
Fortunately, current quality has not been sacrificed in order just to earn money on the name. Farming out the production to a dedicated and very capable company has kept their centuries old reputation afloat.
Further to company identity: "the proof of the pudding comes in the eating". Since (unlike the case of the self-owning Zeiss foundation) publicly listed shares can be bought by anyone, the "identity" of companies can change over time, so in a globalized world, do not trust the name, trust the product.
Land Rover for instance was swallowed by BLC when Rover died, then had German, American and Indian owners. Occasionally parent company parts, but always the same British factory. Jaguar had a more chequered career with the same sequence of owners. One model was a Ford in pimped up disguise, but (And like the original SS Swallow) the buyers were happy to get the presumably expensive trappings cheaply. One can no longer buy the XK engine but current needs differ from way back then. Again, the collectors market can supply the original stuff. Unlike for cameras, however, maintenance costs may give you cause to hesistate.
p.