Combined holography and thermography in a single sensor through image-plane holography at thermal infrared wavelengths

in Optics Express (2014), 22(21), 25517-25529

Holographic interferometry in the thermal wavelengths range, combining a CO2 laser and digital hologram recording with a microbolometer array based camera, allows simultaneously capturing temperature and ... [more ▼]

Holographic interferometry in the thermal wavelengths range, combining a CO2 laser and digital hologram recording with a microbolometer array based camera, allows simultaneously capturing temperature and surface shape information about objects. This is due to the fact that the holograms are affected by the thermal background emitted by objects at room temperature. We explain the setup and the processing of data which allows decoupling the two types of information. This natural data fusion can be advantageously used in a variety of nondestructive testing applications. [less ▲]

Simultaneous Temperature and Deformations Measurements Using Long-Wave Infrared Speckle Interferometry: A Novel Hybrid Technique for Industrial Nondestructive Testing

in Osten, Wolfgang (Ed.) Fringe 2013 (2014)

The use of long-wave infrared (LWIR) CO2 lasers and microbolometer arrays in digital holographic and speckle interferometry shows interesting features for full-field displacement/deformation metrology and ... [more ▼]

The use of long-wave infrared (LWIR) CO2 lasers and microbolometer arrays in digital holographic and speckle interferometry shows interesting features for full-field displacement/deformation metrology and nondestructive testing. The first one is that the long wavelength yields the measurement of larger displacements together with decreasing the sensitivity to environmental perturbations. Therefore these interferometric methods can be applied more easily in industrial field applications. Another advantage was put forward in the European project FANTOM which is presented in this paper. In addition to specklegrams, the thermal background is captured simultaneously. Therefore in displacement metrology one can correlate uniquely the temperature and displacement information at the same time and in each pixel. We describe the successful achievements of the project. Thorough understanding of optics and speckle interferometry crossed with state-of-art in thermam imaging systems allowed to study this new hybrid technique in deep and tackle some specific constraints for reaching the best performances. As a result, a mobile instrument has been developed and validated on various industrial structural testing facilities and inspection areas. It has been used in thermomechanical measurements as well as in detection of defects in aeronautical composites. In particular we show that the two parts of the signal (the thermal part on one hand and the interferograms showing the deformation on the other hand) yield complementary information. A very interesting result is that it allows increasing the probability of detecting defects, for some of them are better seen in the thermal signal, whereas others appear only through local surface deformation. [less ▲]

Nondestructive testing by using long wave infrared interferometric techniques with CO2 lasers and microbolometer arrays

in Applied Optics (2013), 52(1), 57-67

We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, digital shearography), using a long wave infrared radiation produced ... [more ▼]

We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, digital shearography), using a long wave infrared radiation produced by a CO2 laser and recording on a microbolometers array. Experimental results showing how these methods can be used for nondestructive testing are presented. Advantages and disadvantages of these approaches are discussed. [less ▲]

Digital Holographic Interferometry and ESPI at Long Infrared Wavelengths with CO2 Laser (invited paper)

in Digital Holography and 3D Imaging (DH2012) (2012, April 28)

Electronic speckle pattern interferometry in Long Wave Infrared: a new technique for combining temperature and displacement measurements. Applications in thermo-mechanical assessment of structures

in Proceedings of ICSO 2010 - International Conference on Space Optics (2010, October)

Digital holographic interferometry by using long infrared radiation (CO2 laser)

in Advances in Experimental Mechanics VII (2010, September)

We show how digital holographic interferometry in the Long Wave InfraRed (LWIR) spectral range can be used for the investigation of mechanical structures. The 10.6 μm radiation is produced by a CO2 Laser ... [more ▼]

We show how digital holographic interferometry in the Long Wave InfraRed (LWIR) spectral range can be used for the investigation of mechanical structures. The 10.6 μm radiation is produced by a CO2 Laser. Experimental results showing that the method can be used to locate defect in a panel are presented and advantages and disadvantages of this approach are discussed [less ▲]

Automated Phase Map Referencing Against Historic Map Data

in Osten, W.; Kujawinska, M. (Eds.) Fringe 2009 (2009, September)

Holography and shearography techniques are in common use for precise measurements in high technology industries, such as aerospace, automotive, precision manufacturing and for the structural diagnostics ... [more ▼]

Holography and shearography techniques are in common use for precise measurements in high technology industries, such as aerospace, automotive, precision manufacturing and for the structural diagnostics of artwork. The phase map data generated by these instruments allows precise measurements of parameters such as displacement, strain and shape. The comparison of data from different measurement campaigns is useful for null testing components and for studying changes. However, the comparison of data with previous measurements is non-trivial due to the sensitivity of these techniques to alignment and to sample loading parameters. This paper addresses image and phase registration issues for holography and shearography. This manuscript describes 2D spatial co-registration to compensate for differences between the field of view between the measurements and a phase referencing to calculate the difference between the phase maps. These techniques are implemented after following a standardised measurement procedure. [less ▲]

Interférométrie holographique sur base de cristaux photoréfractifs dynamiques et lasers à double impulsion : le projet européen PHIFE

in Smigielski, P. (Ed.) Actes du Cinquième colloque francophone Méthodes et Techniques Optiques pour l'Industrie (2004, November)

Les cristaux photoréfractifs sont des supports holographiques dynamiques (auto-enregistrables, effaçables et indéfiniment réutilisables) qui permettent l'acquisition rapide d'hologrammes utilisables en ... [more ▼]

Les cristaux photoréfractifs sont des supports holographiques dynamiques (auto-enregistrables, effaçables et indéfiniment réutilisables) qui permettent l'acquisition rapide d'hologrammes utilisables en interférométrie holographique. De plus, certaines de leurs propriétés cristallines permettent l'obtention d'interférogrammes de qualité incomparable. Nous avons déjà présenté à maintes reprises les développements et applications d'instruments de métrologie basés sur ces cristaux avec des lasers continus. Des expériences préliminaires sur base de lasers à simple impulsion avaient aussi été montrées. Nous présentons ici la suite de ces expériences et qui ont lieu dans le cadre du projet européen PHIFE "Pulsed Holographic Interferometer for the analysis of Fast Events". PHIFE a pour objectif le développement d'un instrument à champ complet fonctionnant avec un laser YAG Q-switch à double impulsion. [less ▲]

Pulsed holographic interferometry with photorefractive crystals. Recent advances of the european “PHIFE” project

Conference (2004, March)