Digital holographic interferometry in the long-wave infrared domain has been developed by combining a CO(2) laser and a microbolometer array. The long wavelength allows large deformation measurements, which are of interest in the case of large space reflectors undergoing thermal changes when in orbit. We review holography at such wavelengths and present some specific aspects related to this spectral range on our measurements. For the design of our digital holographic interferometer, we studied the possibility of illuminating specular objects by a reflective diffuser. We discuss the development of the interferometer and the results obtained on a representative space reflector, first in the laboratory and then during vacuum cryogenic test.

Electronic speckle pattern interferometry and digital holographic interferometry are investigated at long infrared wavelengths. Using such wavelengths allows one to extend the measurement range and decrease the sensitivity of the techniques to external perturbations. We discuss the behavior of reflection by the object surfaces due to the long wavelength. We have developed different experimental configurations associating a CO(2) laser emitting at 10.6 μm and microbolometer arrays. Phase-shifting in-plane and out-of-plane electronic speckle pattern interferometry and lensless digital holographic interferometry are demonstrated on rotation measurements of a solid object.

We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, and digital shearography), using a long-wave infrared radiation produced by a CO 2 laser and recorded on a microbolometer array. Experimental results showing how these methods can be used for nondestructive testing are presented. Advantages and disadvantages of these approaches are discussed.

Abstract. We present the development of a speckle interferometer based on a CO 2 laser and using a thermal infrared camera based on an uncooled microbolometer array. It is intended to be used for monitoring deformations as well as detecting flaws in aeronautical composites, with a smaller sensitivity to displacement compared to an equivalent system using visible (VIS) lasers. Moreover the long wavelength allows working with such interferometers outside the laboratory. A mobile system has been developed on the basis of previous laboratory developments. Then it is validated in a variety of industrial nondestructive testing applications in field working conditions.

Holographic interferometry in the thermal wavelengths range, combining a CO 2 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. 16(4), 187-192 (1984). 9. E. Allaria, S. Brugioni, S. De Nicola, P. Ferraro, S. Grilli, and R. Meucci, "Digital holography at 10.6 µm," Opt. ©2014 Optical Society of AmericaCommun. 215(4-6), 257-262 (2003). Meucci, P. Ferraro, and P. De Natale, "Mid-infrared digital holography and holographic interferometry with a tunable quantum cascade laser," Opt. Lett. 39(16), 4843-4846 (2014).