Iterative phase-retrieval-assisted off-axis terahertz digital holography.

In terahertz digital holography, the off-axis configuration is the appropriate choice when the investigated object is non-sparse and complex. The limitation of recording distance in the off-axis configuration restricts the imaging quality. Either low-resolution or spectra overlap can potentially occur.

Digital holographic interferometry and speckle interferometry applied on objects with heterogeneous reflecting properties.

In digital holographic and speckle interferometry devoted to solid object displacement measurement, the reflecting properties of the object under study are of importance in designing the observation and laser illumination systems. In practical cases, the objects can show separate zones in which the surface property can simultaneously cause either scattering or specular reflectivity. We present strategies for dealing with both reflectivity types at a time in digital holographic and speckle interferometers.

Determination of vibration amplitudes from binary phase patterns obtained by phase-shifting time-averaged speckle shearing interferometry.

Speckle shearing interferometry (shearography) is a full-field strain measurement technique that can be used in vibration analysis. In our case, we apply a method that combines the time-averaging and phase-shifting techniques. It produces binary phase patterns, where the phase changes are related to the zeroes of a Bessel J function, typical of time-averaging.

Space mirror deformation: from thermo-mechanical measurements by speckle interferometry to optical comparison with multiphysics simulation.

Experimental testing of space optics is a mandatory process for investigating the optical performances in conditions close to reality. With the optical requirement level increasing over years, these experimental tests are increasingly expensive and time-consuming. A modeling tool would therefore be an elegant solution to avoid these drawbacks.

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

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.

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

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.

Digital holographic interferometry with CO2 lasers and diffuse illumination applied to large space reflector metrology [Invited].

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.

Electronic speckle pattern interferometry and digital holographic interferometry with microbolometer arrays at 10.6 μm.

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.