Ghost Imaging Captures Clear Reconstructions of Moving Objects

Researchers at the National University of Defense Technology (NUDT) have used ghost imaging to capture an image of a moving object. The new method, which creates clear reconstructions by combining information found in the blurry images of a moving object with details about the object’s location, could expand applications for ghost imaging in the areas of biomedical imaging, security, and video compression and storage.

The need for a large number of samplings limits the performance of ghost imaging for moving objects. It takes a long time to project the sequence of light patterns onto an object that is necessary to construct a ghost image. This causes images of a moving object to appear blurry, and it’s why ghost imaging has been used primarily for stationary objects.

In conventional systems, the tracking and imaging of the moving object are done independently; thus, sequential clear images of the moving target during its evolution are required. To apply ghost imaging to moving objects, the NUDT researchers used a small number of light patterns to capture the position and trajectory of the object and developed an algorithm to cross-correlate this positional information with sequential blurred images captured at different positions. This approach allowed a high-quality image of the moving object to be gradually formed. The researchers said that their method works well for translating and rotating objects.

“This approach relaxes the requirement for fast imaging, and because the algorithm is linear, it doesn’t require a large amount of computing power,” professor Wei-Tao Liu said. “The method can be performed with a typical ghost imaging system without any additional devices and allows the image to be reconstructed in a timely manner.”

The researchers demonstrated their new method using a typical ghost imaging system, in which a random light field generated by a rotating diffuser was divided into two beams. One beam was recorded by a CCD camera, while the other beam illuminated a moving object created by the researchers using a digital micromirror device. The light coming from the moving object was collected by a single-pixel detector.

Researchers used ghost imaging to capture images of the translating and rotating object in the first row. They used information in the blurry images (middle row) to create the reconstructed images in the bottom row. Courtesy of Wei-Tao Liu, National University of Defense Technology.

“We demonstrated that our method captured the trajectory of the image and formed a high-quality image,” Liu said. “With these same experimental conditions, traditional ghost imaging approaches would have lost most of the object information due to blurring from movement.”

The researchers are improving the performance of their approach so that it will work for objects moving at higher speeds. They also want to further reduce the amount of light needed to use their approach.

The research was published in Optics Letters, a publication of The Optical Society (OSA) (www.doi.org/10.1364/OL.44.005594).