Depth-resolved whole-field displacement measurement by wavelength-scanning electronic speckle pattern interferometry.
We show, for the first time to our knowledge, how wavelength-scanning interferometry can be used to measure depth-resolved displacement fields through semitransparent scattering surfaces. Temporal sequences of speckle interferograms are recorded while the wavelength of the laser is tuned at a constant rate. Fourier transformation of the resultant three-dimensional (3-D) intensity distribution along the time axis reconstructs the scattering potential within the medium, and changes in the 3-D phase distribution measured between two separate scans provide the out-of-plane component of the 3-D displacement field. The principle of the technique is explained in detail and illustrated with a proof-of-principle experiment involving two independently tilted semitransparent scattering surfaces. Results are validated by standard two-beam electronic speckle pattern interferometry.
Ruiz
Pablo D
PD
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK. p.d.ruiz@lboro.ac.uk
Huntley
Jonathan M
JM
Wildman
Ricky D
RD