Volkseigener Betrieb
In 1955, Hartmann founded and became the director of the "Volkseigener Betrieb Vakutronik Dresden" (VEB Dresden, Dresden Vakutronik People's Enterprise); later, it became the "Volkseigener Betrieb Rundfunk-und-Fernmeldewesen Meßelektronik Dresden" ("VEB RFT Meßelektronik Dresden", Dresden Radio and Telecommunications Technology Measurements Electronics People's Enterprise).