Description: The mechanical shutter, invented by Pat Keller, et al., at China Lake in the 1980s, helped freeze the action and eliminate ghosting. This was a mechanical shutter similar to the one used in high-speed film camerasˇŞa disk with a wedge removed. The opening was synchronized to the frame rate, and the size of the opening was proportional to the integration or shutter time. By making the opening very small, the motion could be stopped.Despite the resulting improvements in image quality, these systems were still limited to 60 frame/s.