Abstract:
Optical methods of vibration evaluation comprise a very powerful tool in areas such as quality control and predictive maintenance. We propose and experimentally demonstrate a technique for out-of-plane, whole-field vibration analysis by studying the visibility decrease of projected structured light on vibrating surfaces. The light pattern formed by straight, parallel, and sinusoidal fringes originates from an incoherent source and impinged the object obliquely. The pattern visibility is the zeroth-order Bessel function of the amplitude and is retrieved from phase-stepping procedures. The amplitude distribution in turn is determined with the help of the first-order Runge–Kutta method. For fringe evaluation, a novel phase stepping routine was proposed, expressions for four-, six-, and eight-stepping were derived, and the four- and eight-step procedures were compared in the experiments, providing rather close results. Using an illuminating mirror oscillating with a frequency slightly different from that of the object, the vibration phase has been also determined. The dynamical range of measured amplitudes lies from hundredths of millimeters to a few millimeters and has shown to be significantly larger than the ones provided by other optical and interferometric techniques. The simplicity of the method may enable the construction of rugged and compact setups, which do not require any severe conditions or special procedures to prevent external perturbations or avoid noisy environments.
Referência:
OHQUI, Felipe Cazzarini; SAITA, Marcelo Tadao; BARBOSA, Eduardo Acedo. Vibration measurement technique by structured light visibility analysis. OE Optical Engineering, v.64, n.5, 054106, May, 2025.
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