Compact infrared cryogenic wafer-level camera: design and experimental validation

International audienceWe present a compact infrared cryogenic multichannel camera with a wide field of view equal to 120 degrees. By merging the optics with the detector, the concept is compatible with both cryogenic constraints and wafer-level fabrication. The design strategy of such a camera is described, as well as its fabrication and integration process. Its characterization has been carried out in terms of the modulation transfer function and the noise equivalent temperature difference (NETD). The optical system is limited by the diffraction. By cooling the optics, we achieve a very low NETD equal to 15 mK compared with traditional infrared cameras. A postprocessing algorithm that aims at reconstructing a well-sampled image from the set of undersampled raw subimages produced by the camera is proposed and validated on experimental images. (C) 2012 Optical Society of Americ

Compact infrared pinhole fisheye for wide field applications

International audienceThe performances of a compact infrared optical system using advanced pinhole optics for wide field applications are given. This concept is adapted from the classical Tisse design in order to fit with infrared issues. Despite a low light gathering efficiency and a low resolution in comparison with classical lenses, pinhole imagery provides a long depth of field and a wide angular field of view. Moreover, by using a simple lens that compresses the field of view, the angular acceptance of this pinhole camera can be drastically widened to a value around 180{\textdegree}. This infrared compact system is named pinhole fisheye since it is based on the field lens of a classical fisheye system

Spatial coherence: interferometer design and the localisation of interference fringes

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Generation of achromatic and propagation-invariant spot arrays by use of continuously self-imaging gratings

International audienceA particular class of Montgomery's self-imaging objects that we call continuously self-imaging gratings (CSIG's) is introduced. When they are illuminated by a plane wave, these objects produce a field whose intensity profile is a propagation- and wavelength-invariant biperiodic array of bright spots. The mathematical construction of these objects and their intrinsic properties are described. On a practical level, CSIG's are compact and achromatic nondiffracting array generators. We show that a good CSIG approximation can be realized by a two-level phase grating that is experimentally tested

Optiques binaires et application à l'imagerie - Optiques focalisantes

International audienceThis paper studies the imagery properties of binary optics which are optical components that can be coded by a succession of patterns, either opaque or transparent; or etched or not etched. Compared to conventional optical components that use the refraction or reflection to modify the path of the light, the binary optics use the diffraction property of the light thanks to its wave nature. Focusing binary optics will be addressed, that concentrate light at a single focal point and whose properties are close to conventional optics.L’article traite des propriétés d’imagerie des optiques binaires qui sont des composants optiques codés par une succession de motifs, soit opaques ou transparents, soit gravés ou non gravés. Par rapport aux composants optiques classiques qui utilisent la réfraction ou la réflexion pour modifier la direction des rayons lumineux, les optiques binaires exploitent le phénomène de la diffraction qui sollicite l’aspect ondulatoire de la lumière. Sont développées les optiques binaires focalisantes, c'est-à-dire qui concentrent la lumière en un point focal et dont les propriétés sont proches de celles d’une optique classique