Laser-induced fluorescence-dip spectroscopy is considerably modified by using a special broad band dye laser. With a linewidth of the laser of 1 nm, it is possible to detect a wide spectrum of the relevant Stark shifts in order to measure the weak electric fields in plasmas. Depending on the selection of the Rydberg level, the measuring range extends from about 100 V/cm to a few kV/cm. The main advantage of the newly developed method is the possibility to obtain the complete image of the field distribution in a wide spatial area over a few cm within one measurement step at a given time. This allows reliable electric field measurements for phenomena with poor pulse-to-pulse reproducibility on the microscale. The basics of the method and first experimental test results are presented in detail.