Transient deformation measurement by double-pulsed-subtraction TV holography and the Fourier transform method

Abstract

We report the measurement of transient bending waves with double-pulsed-subtraction TV holography. The correlation fringe patterns are automatically quantitatively analyzed by the application of Fourier methods. A novel optical setup with two different object-beam optical paths is demonstrated for the generation of carrier fringes. The proposed system is highly immune to environmental disturbances because the optical setup imposes no lower limit on the time separation between laser pulses. One removes the linear phase distribution due to the spatial carrier in the spatial domain by subtracting the phase of the undeformed carrier fringes from the phase of the modulated fringes. Experimental results obtained with an aluminum plate excited by the impact of a piezoelectric translator are presented.

Single‐Image Interferogram Demodulation

“…The Fourier transform method (FTM) is one of the most widely used tools for recovering the phase of a single interferogram with spatial carrier frequency [2][3][4]. Actually, this is the de facto tool in interferometry techniques such as digital TV holographic [5].…”

An improved mixed numerical-experimental method for stress field calculation

“…This way; they can be applied over diffuse and complex geometry surfaces without interfering with its structural behavior. With these techniques quasi-static, periodic or transient phenomena can be studied by selecting continuous emission or pulsed lasers [4][5][6][7][8][9].…”

Extended-range temporal electronic speckle pattern interferometry

“…Temporal fringe pattern analyses applied to the study of transient phenomena by using electronic speckle pattern interferometry ͑TESPI͒ has been an intense research subject in recent years. Even though high-power double-pulse lasers have been used for this purpose, [1][2][3] sometimes a quantitative analysis cannot be obtained because of the difficulty of demodulating ESPI fringe patterns containing high-density closed fringes. 2 In recent years high-speed CCD digital video cameras for the optical laboratory are capable of obtaining more than 45,000 digital pictures per second.…”