As of 2012, ARL scientists developed a diffraction-free light beam, also called Bessel beam illumination. In a paper published February 10, 2012, the team outlined their feasibility study of virtual ghost imaging using the Bessel beam, to address adverse conditions with limited visibility, such as cloudy water, jungle foliage, or around corners. Bessel beams produce concentric-circle patterns. When the beam is blocked or obscured along its trajectory, the original pattern eventually reforms to create a clear picture.