Movie 1.

Video illustrating the principle of the experimental setup using a defocused thermal imaging camera. When the camera is defocused at the start of the video, the background plate is not resolved by the imaging system and the moving pendulum target cannot be distinguished from the background because it is the same temperature as the average background temperature. When the camera is focused, the patterning of the background is resolved as a series of warmer and cooler areas, and the moving pendulum target is seen more clearly.