Vibration measurement by the time-averaged electronic speckle pattern interferometry methods

Abstract

Three different image-processing methods based on the time-averaged technique were compared by the electronic speckle pattern interferometry (ESPI) technique for vibration measurement. The three methods are the video-signal-addition method, the video-signal-subtraction method, and the amplitude-fluctuation method. Also, errors introduced by using the zero-order Bessel function directly into the analysis of the fringe pattern were investigated. The video-signal-addition method has been the most generally used ESPI technique for vibration measurement. However, without additional image and/or signal-processing procedures, the fringe pattern obtained directly by the video-signal-addition method is rather difficult to observe. The reason for poor visibility of the experimentally obtained fringe pattern with this method is explained. To increase the fringe pattern's visibility without additional image and/or signal processes, we tried two video-signal-subtraction methods. One of the two methods is the video-signal-subtraction method that has normally been used in the static applications. The other method, called the amplitude-fluctuation method, and its associated theory are reported here.

Investigation on Non-Linear Vibration Response of Cantilevered Thin Plates with Crack Using Electronic Speckle Pattern Interferometry

“…Figure 2 illustrates the schematic diagram for deflection vibration measurement using the timeaverage electronic speckle pattern interferometry (ESPI) in this study. For the space limit, the measurement principle of ESPI method is not introduced in this paper, the readers can refer the literature [11] for detail. The sinusoidal vibration is measured during a frequency sweep using the optical setup illuminated in Figure 2.…”

Vibration analysis based on electronic stroboscopic speckle-shearing pattern interferometry

“…Compared with the stroboscopic method, the experimental set up of time-averaged method is low-cost and easy to establish, so the time-averaged method is widely used for the vibration measurement [2]. But it is difficult to quantitatively evaluate the fringe pattern, so the stroboscopic illumination technique is introduce into the ESSPI in order to get the phase map of the fringe pattern [9].…”

“…Its advantages are of real-time observation, high measurement sensitivity, the elimination of chemical development, the independent measurement of orthogonal displacement components [2] and tolerance to environment disturbances [3]. There are many techniques for measuring the vibration of the object, such as laser stroboscopic [4]，Laser-Doppler vibrometry [5], the simulation technique [6] and ESPI.…”

Mode shape visualization system for high-stability quartz resonators in high and continuously changing temperature

“…Measuring the vibration mode shape is crucial when designing piezoelectric resonators or vibration devices, and several methods for plotting these mode shapes have been developed [1][2][3][4][5][6]. Many of the methods use optical interference, which is the interaction between incident and reflected photons produced by coherent laser beams.…”