Investigating into Minimum Detectable Displacement Signal in Image-Based Vibration Measurement

Image-based vibration measurement is becoming more and more popular due to its critical advantages of non-contact and full-field measurement. However, the minimum detectable displacement of a measurement system still lacks a theoretical study and experimental verification. When measuring vibration displacement of micron scale, it becomes difficult to distinguish the signal from noises. Therefore, this paper puts forward an explicit equation to calculate the minimum detectable signal (MDS) of displacement in vibration measurement using high-speed camera. The influence factors including blurring, color depth, image noise, and resolution are all included in the equation, which presents how these factors impact on the MDS. A simulation test is conducted on synthetic image and results show a great agreement with theoretical prediction. Furthermore, the equation of MDS is validated by an experimental study on modal analysis.