Development of a video trigger for ultra high-speed video camera

An ultra high-speed video camera whose frame rate is 1 million frames/second was developed by a cooperative R and D project of Kinki University and Shimadzu Corporation in September, 2001. In this ultra high-speed video camera, the continuous overwriting system is used. Number of recorded frame is 103. In case of high-speed image capturing, a method of sending a trigger signal for stopping continuous overwriting becomes important. Currently available trigger systems are mainly a trigger by sound and a trigger by laser. In the case of image capturing of a bursting balloon, we can use the sound and/or laser trigger. However, it is difficult to capture images at an ultra-high frame rate under a microscope. A video trigger system, which can be applied to microscopic ultra high-speed image capturing, is under development. In this paper, an algorithm for detection of a sudden change of brightness in an image is presented.