Jürgen Bischoff, a 49-year-old executive who worked previously for the RWE power company, is taking over this month the management of Carl Zeiss' consumer optics division. His predecessor, 44-year-old Klaus Weissenberger, has decided to leave the company next Aug. 31 after 3 years in the job. A major reorganization program initiated by Weissenberger has apparently paid off. Sales of the division, which doesn't include photo lenses anymore, grew by 16 percent to 391 million DM (e200m-$182m) in the 6 months ended last March 31.