X-ray diffraction has been used to study CdTe layers grown by molecular beam epitaxy on Cd0.96Zn0.04Te or InSb substrates with either (111) or (001) orientation. The layers are elastically strained up to a critical thickness, above which misfit dislocations are generated. Our experimental determinations of the critical thickness and the relaxation of the stress while increasing the layer thickness are different from predictions of the existing models. We present a discussion of relaxation based on the determination of the minimum energy state of the layer for a given thickness. We show that above the critical thickness, the layer relaxes so that the product of the stress by the thickness remains constant. This constant has been experimentally determined for both (111) and (001) orientation.

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We designed a compact infrared cryogenic camera using only one lens mounted inside the detector area. In the field of cooled infrared imaging systems, the maximal detector area is determined by the dewar. It is generally a sealed and cooled environment dedicated to the infrared quantum detector. By integrating an optical function inside it, we improve the compactness of the camera as well as its performances. The originality of our approach is to use a thin integrated optics which is a high quality Fresnel lens on a thin germanium substrate. The aim is to reduce the additional mass of the optical part integrated inside the dewar to obtain almost the same cool down time as a conventional dewar with no imaging function. A prototype has been made and its characterization has been carried out.

Adaptive optics provide real-time compensation for atmospheric turbulence. The correction quality relies on a key element: the wavefront sensor. We have designed an adaptive optics system in the mid-infrared range providing high spatial resolution for ground-to-air applications, integrating a Shack-Hartmann infrared wavefront sensor operating on an extended source. This paper describes and justifies the design of the infrared wavefront sensor, while defining and characterizing the Shack-Hartmann wavefront sensor camera. Performance and illustration of field tests are also reported.

We present a prototype of an infrared cryogenic camera directly integrated inside an off-the-shelf SOFRADIR's Detector Dewar Cooler Assembly (DDCA) and whose field of view is equal to 120°. Based on the co-design principle between optical design and image processing, we have designed a multichannel camera which produces four non-redundant images on a single SCORPIO detector, with 640 x 512 pixels and a pixel pitch of 15 µm. This leads to an ultraminiaturized optical system with a very low additional optical and mechanical mass to be cooled. By this way, the cooldown time of the camera is comparable to the one of an equivalent DDCA without an imagery function. Indeed, we obtain a cool-down time of 6 minutes with a THALES Cryogenics RM3. With a superresolution algorithm, the four images produced by the camera are combined to process a single full-resolution image with an equivalent sampling pitch equal to 7.5µm. The performances of this camera, assessed by experimental characterizations, are presented.