Laboratory for Dynamics of Machines and Structures 
Measuring full-field displacement spectral components using photographs taken with a DSLR camera via an analogue Fourier integral
 J. Javh, J. Slavič and M. Boltežar
Mechanical Systems and Signal Processing, Vol. 100, p. 17-27, Feb 2018

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Abstract
Instantaneous full-field displacement fields can be measured using cameras. In fact, using high-speed cameras full-field spectral information up to a couple of kHz can be measured. The trouble is that high-speed cameras capable of measuring high-resolution fields-of-view at high frame rates prove to be very expensive (from tens to hundreds of thousands of euro per camera). This paper introduces a measurement set-up capable of measuring high-frequency vibrations using slow cameras such as DSLR, mirrorless and others. The high-frequency displacements are measured by harmonically blinking the lights at specified frequencies. This harmonic blinking of the lights modulates the intensity changes of the filmed scene and the camera-image acquisition makes the integration over time, thereby producing full-field Fourier coefficients of the filmed structure's displacements.
Authors

Young researcher

Jaka Javh, PhD Student

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  jaka.javh@fs.uni-lj.si
  +386 1 4771 603

Associate Professor

Janko Slavič, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  janko.slavic@fs.uni-lj.si
  +386 1 4771 226
jankoslavic     jankoslavic    
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Professor

Miha Boltežar, PhD

  Ladisk, Faculty of Mechanical Engineering, University of Ljubljana
  miha.boltezar@fs.uni-lj.si
  +386 1 4771 608
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