X-ray ghost imaging

In its basic form, ghost imaging is a technique that indirectly produces a likeness of an object by combining the information from two light detectors—one that views the object and one that doesn’t. By splitting a speckled laser beam so that two beams strike spatially separated locations on a CCD camera screen and by placing an object in one of the beams, as shown here, researchers can calculate the intensity correlations between the two signals as the beams are scanned in synchrony and construct the object’s ghost image. Demonstrated in 2002 using visible light, the technique holds promise for remote atmospheric sensing because of its insensitivity to turbulence. Two research groups have now extended ghost imaging to the hard x-ray regime. Daniele Pelliccia (RMIT University in Australia) and his colleagues passed an x-ray beam produced by the European Synchrotron source through a diffracting silicon crystal grating oriented to transmit...