Role of mirror dynamics in determining the accuracy of framing rate in an ultra high speed rotating mirror camera

We investigated the occurrence of small but significant inaccuracies in the temporal integrity of a commercial high-speed [rotating mirror] imaging system (a Cordin 550-62 camera). Utilizing a relatively straightforward hardware addition, independent measurements of the actual frame rate at the point of camera triggering were conducted, and then compared to the Cordin system's self-reported frame rate values for each recording. The present data thus represents a follow-up to our earlier preliminary report on this instrument's performance, where we initially discovered that disparities between the true and reported values could arise(1). Interestingly, the data trends observed in the present report suggest a disparity, the nature of which is consistent with the Cordin camera reporting a frame rate that arises a short time before the trigger event, i.e. that the system's sampling algorithm senses the frame rate with a finite pre-trigger implemented, which runs counter to the procedure suggested by the manufacturer. As well as presenting the context, and supporting evidence for our own conclusions, we also developed an approach to reduce the error in the reported values by a factor of 7, from an average of 0.78% +/- 0.04% to 0.11% +/- 0.08% over the present data set.