A novel 4 wavelength laser/BDU set-up for R&D in utrasound testing of aircraft components. A multi-pivoted arm ending in galvo scanner positions a CO2 TEA laser beam spot with precise dimensions and azimuth control over the scan field. A Nd-YAG probe beam is positioned anywhere on the perimeter of a circle of selected diameter centered on the CO2 spot. Both spots locations are indicated by different colour diode laser markers.