Non-contact 1D vibration analysis in temporal digital speckle photography

This paper presents the non-contact 1D laser vibrometer based on the temporal digital speckle photography (TDSP). Speckle dynamics is recorded by means of the linear CCD sensor and continuously acquired line by line into the memory buffer forming in a such way bitmap image with the temporal speckle trajectories. The waveform of the one or several speckle traces can be extracted in digital format using edge filtering in combination with the single- and multitrace algorithms. The resolution and the frequency limit of the TDSP technique directly depends on a clock frequency and pixel pitch of the linear CCD detector used in the laser vibrometer. With modern CCD devices the frequency window limited by 2000 Hz and the resolution of about ∼2.6μm can be reached. The described technique represents cheap solution for realtime visualization and registration of fast uniaxial vibrational processes.