Defence group Chemring, which makes anti-aircraft and roadside bomb counter-measures, has bought sub-surface imaging company 3d-Radar for $3m. Norway-based 3d-Radar, part of Curtiss-Wright Corporation, develops commercial three-dimensional ground-penetrating radar (GPR) technology which can speed up and improve the accuracy of 3D imaging of underground structures. 3d-Radar's patented GPR technology has already been successfully tested and used for sub-surface imaging in road and railway maintenance and airport runway inspection. Chemring plans to fund the deal from cash resources. Chemring Chief Executive Mark Papworth said the deal would allow it to improve its roadside bomb detection products and exploit commercial opportunities."This small but strategically important acquisition consolidates Chemring's position as a world leader in GPR technologies."Chemring's shares fell 3.25p or 1.5% to 217p at 09:28 in London.PW