Speckle correlation methods applied to ballistics and explosives

Image correlation techniques developed for speckle metrology have recently been applied to a wide range of ballistics and explosives studies at the Cavendish Laboratory. White-light image correlation applied to quasi-static testing of explosives, at a range of magnifications, is discussed. High-speed ballistic measurements were performed using Digital Speckle Radiography (DSR): a combination of image correlation with flash X-rays to study the movement of a plane of X-ray opaque filings within a sample. DSR operates by capturing one image before and a second during the event, allowing the displacements on the plane to be measured to sub-mm accuracy. Varying the delay time and the depth of the seeded plane gives a full three-dimensional. flow field in the sample. The use of two X-ray heads stereoscopically increases accuracy by allowing all three components of displacement to be determined. Measurements at velocities ranging from 100 in s(-1) to 6 km s(-1) have been achieved using this technique.