2.1. Vegetation illumination
Fig. 2 shows the layout of the plant discrimination unit and illustrates how laser beams are generated to illuminate the vegetation.
2.1.1. Beam generation
Each laser module uses three 4 mm collimated laser sources, two red (635 nm and 685 nm) lasers and one near-infrared (785 nm), with output power levels of 30 mW, 50 mW and
50 mW, respectively. Within a module, each laser is independently mounted onto an alignment stage using alignment screws, so that all laser beams are aligned along the same optical axis. Two fixed,