The Molecular-Beam-Deposition-LEED is an instrument for the in-situ observation of thin film growth during the evaporation process. It combines 3 miniature Knudsen cells with the SPECTALEED for simultaneous and independent evaporation of up to three different materials. The Knudsen cells are integrated into the LEED optics so as to cause minimum reduction of the LEED viewing area and no disturbance of the LEED pattern.

Low light emission is maintained even at the maximum evaporation temperature of approx. 700°C. The quartz glass crucibles are prealigned onto the sample and are easily exchanged and refilled. The design geometry prevents contamination of the LEED grids by the evaporant.