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Speckle Interferometry

Introduction

The speckle metrology research area at Cranfield has expertise in a wide range of speckle interferometry and associated optical techniques. The non-contact full-field optical measurements that are made using these techniques are increasingly important for investigation of the behaviour of materials in high technology applications, such as in the aerospace and automotive industries.

 

Theory

Shape and vibration measurement using ESPI and shearography

Surface strain measurement using multi-component shearography

Pulsed laser shearography with coherent fibre-optic imaging bundles

 

Researchers

Dr. Daniel Francis - Cranfield PhD thesis 2008

Prof. Stephen W. James

Prof. Ralph P. Tatam

 

Selected Publications

 A mechanically stable laser diode speckle interferometer for surface contouring and displacement measurement
D Francis, D Masiyano, J Hodgkinson and R P Tatam
Measurement Science and Technology 26(5), 055402 (2015) - Open Access

Frequency division multiplexing for multi-component shearography 
I Bledowski, T O H Charrett, D Francis, S W James and R P Tatam
Applied Optics 52, 350-358 (2013)
CERES: https://dspace.lib.cranfield.ac.uk/handle/1826/7821

Quantitative shearography: error reduction by using more than three measurement channels
T O H Charrett, D Francis, and R P Tatam
Applied Optics,  50, 134-146 (2011)
CERES: https://dspace.lib.cranfield.ac.uk/handle/1826/5066

Shearography technology and applications: a review
D Francis, R P Tatam and R M Groves*
Measurement Science and Technology, 21, 102001 (2010)
* TU Delft, Netherlands 

Surface strain measurement of rotating objects using pulsed laser shearography with coherent fibre-optic imaging bundles
D Francis, S W James and R P Tatam
Measurement Science and Technology 19, 105301 (2008)

Surface strain measurement using multi-component shearography with coherent fibre-optic imaging bundles
D Francis, S W James and R P Tatam
Measurement Science and Technology 18, 3583–3591 (2007)

Surface strain measurement: a comparison of speckle shearing interferometry and optical fibre Bragg gratings with resistance foil strain gauges
R M Groves, E Chehura, W Li, S W James and R P Tatam
Measurement Science and Technology 18, 1175-1184 (2007)             

Full-field laser shearography instrumentation for the detection and characterisation of fatigue cracks in titanium 10-2-3
R M Groves, D Furfari, S E Barnes, S W James, S Fu, P E Irving, and R P Tatam
Journal of ASTM International, 3, 4 (2006)

Low-coherence optical fibre speckle interferometry
I Balboa, H D Ford and R P Tatam
Measurement Science and Technology, 17 pp 605-616 (2006)

Single-axis combined shearography and digital speckle photography instrument for full surface strain measurement
R M Groves, S Fu , S W James and R P Tatam
Optical Engineering 44, 025602, 2005

Shape and Slope measurement by source displacement in shearography
R Groves, S W James and R P Tatam
Optics and Lasers in Engineering, 41, 621-634, 2004
Special Issue: FASIG

Pipe Weld Investigation using Shearography
R M Groves, S W James and R P Tatam
Strain 39, 101-105, 2003

Shadow Moiré method for the determination of the source position in three-dimensional shearography
R M Groves, S W James and R P Tatam
Optics and Lasers in Engineering, 36, 317-329, 2001.

Polarisation multiplexed and phase-stepped fibre optic shearography using laser wavelength modulation
R M Groves, S W James and R P Tatam
Measurement Science and Technology, 11, 1389-1395, 2000.

Time-division-multiplexed 3D Shearography
S W James and R P Tatam
Presented at Interferometry '99 , Poland, 1999.
Published in SPIE Proc . 3744 , pp 394-403, 1999.

The calibration of the path-length imbalance in optical fibre ESPI systems employing source- wavelength modulation
A Olszak and R P Tatam
Measurement Science and Technology, 8 , pp 759-763, 1997.

Slope Measurement by Two-wavelength Electronic Shearography
J-R Huang, H D Ford and R P Tatam
Optics and Lasers in Engineering, 27 , pp 321-333, 1997.

Heterodyning of speckle shearing interferometers using laser diode wavelength modulation
J-R Huang, H D Ford and R P Tatam
Measurement Science and Technology, 7 , 1721-1727, 1996

Phase-stepped speckle shearing interferometer by source wavelength modulation
J-R Huang, H D Ford and R P Tatam
Optics Letters
, 21 , pp 1421-1423, 1996.

Optoelectronic Developments in Speckle Interferometry
R P Tatam
Invited Paper Presented at the conference Laser Interferometry VIII: Techniques and Analysis , Denver, USA, 1996.
Published in SPIE Proc . 2860 , pp 194-212, 1996.

Heterodyning of Fibre Optic Electronic Speckle Pattern Interferometers using Laser Diode Wavelength Modulation
H Atcha and R P Tatam
Measurement Science and Technology, 5 , pp 704-709, 1994, (Special Issue: Optical Techniques in Measurement)

Optical Fibre Technique for Measurement of Small Frequency Separations: Application to Surface Profile Measurement using Electronic Speckle Pattern Interferometry
H D Ford, H Atcha and R P Tatam
Measurement Science and Technology, No. 5, pp 601-607, 1993.
(Reprinted in Engineering Optics, 6 , pp 301-308, 1993).

Holographic Surface Contouring using Wavelength Modulation of Laser Diodes
R P Tatam, J C Davies, C H Buckberry and J D C Jones
Optics and Laser Technology, 22 , pp 317-321, 1990.

Theory

Principle of Shearography and ESPI   Introduction Speckle metrology encompasses a range of techniques that are used for non-contact, full-field inspection of diffusely reflecting surfaces. These techniques are used to measure a variety of properties including displacement, shape and surface strain, and are becoming increasingly important for material analysis, for example, in the aerospace and …

Shape and Vibration

Measurement of shape and vibration using speckle interferometry   Shape measurement with ESPI One method of measuring shape using ESPI that has been investigated in the EPG is the dual-wavelength technique. This technique involves correlating speckle patterns recorded at two different wavelengths. The result is a fringe pattern where the fringes represent contours of surface …

Multi-component

Surface strain measurement using multi-component shearography Introduction The component of displacement gradient that a shearography instrument is sensitive to is determined by the sensitivity vector k, which is defined as the bisector of the observation vector ô, and the illumination vector î. This is illustrated in figure 1. The sensitivity vector k is made up …

Pulsed shearography

Pulsed laser shearography with coherent fibre-optic imaging bundles   Why use a pulsed laser? The multiple-illumination-direction shearography system built using continuous-wave (cw) DPSS lasers described previously only allows static measurements where a controlled strain is applied between the two camera frames required to make the shearography measurement. In situations where the test object is in …