One possible history of the Optima brand of derailleurs is that it was produced by a company called VEB Optima Büromaschinenwerk in Erfurt in what was then East Germany.
This company had a long and varied history. It started out in 1862 as the Königlich Preußische Gewehrfabrik (the Royal Prussian Rifle Factory), which was moved from Saarn, in the Ruhr, to Erfurt. After the First World War, the Versaille Treaty meant that this factory had to be converted to produce products with peaceful uses - and so it became a typewriter factory. In 1923 AEG bought 50% and then in 1929, acquired 100% of the company and produced various typewriters that seem to warm the hearts of people lonely enough to care about such things (imagine what nerds! - nothing like us derailleur fanatics at all...).
In 1936, the factory produced a model called the ‘Olympia’ in honour of the Berlin Olympic games of that year. This was a success and, in a fit of what now seems like unsavoury enthusiasm, the business was renamed Olympia Büromaschinenwerk AG (Olympia Office Machine Factory).
After the Second World War the factory was initially under Soviet control, but in 1950 was made into a VEB (‘Volkseigener Betrieb’ or ‘organisation owned by the people’, the standard form of state owned business in the DDR). It adopted the name VEB Optima Büromaschinenwerk, because of a dispute with another company which was also using the ‘Olympia’ name.
In the 1960’s the company had 6,900 employees and apparently exported its typewriters all over the world. In 1978 it became part of a conglomerate with the fine name of Robotron. In 1991, after the reunification of Germany, Robotron Optima GmbH was formed from the old VEB, and the Treuhandanstalt vainly tried to privatise it. Various bits of the company were kept alive by management buy-outs, but I believe that exactly none of it exists today.
In terms of derailleurs, the story goes that Optima produced various cycle parts during the 1950s and 1960s including front and rear derailleurs, shift levers and brakes. However this story does not quite answer all my questions about Optima. For example, I have a shift lever which is branded as ‘Optima’ on the lever itself and ‘Renak’ on the pivot cover plate. It is possible that this was put together by someone from the parts of two different levers but...
The most likely explanation would appear to be that there was some cross over between Optima and Renak, with parts sub-contracted out from Optima to Renak and possibly vice versa.