Stationary Fourier transform spectrometry is an interesting concept for building reliable field or embedded spectroradiometers, especially for the mid- and far- IR. Here, a very compact configuration of a cryogenic stationary Fourier transform IR (FTIR) spectrometer is investigated, where the interferometer is directly integrated in the focal plane array (FPA). We present a theoretical analysis to explain and describe the fringe formation inside the FTIR-FPA structure when illuminated by an extended source positioned at a finite distance from the detection plane. The results are then exploited to propose a simple front lens design compatible with a handheld package.

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International audienceA new configuration of micro-spectrometer based on an infrared stationary Fourier transform (FTIR) interferometer has been developed at ONERA. Our device is based on a classic infrared focal plane array (FPA) of HgCdTe technology with a built-in two-wave wedge-like interferometer. This new architecture generates research works in several domains. Technological researches are conducted in collaboration with the CEA to optimize the manufacturing process and reduce the technological defects. In parallel, researches in optical design are conducted to implement the FTIR-FPA in a complete system. For this, theoretical work is needed to understand and describe the fringes formation inside the detection structure when illuminated by a wave which is not ideal, i.e. emitted by an extended source positioned at a finite distance from the detection plane. The results of this theoretical study are presented. These results are exploited to design a compact spectrometer with a very simple optical architecture. First experimental data are presented and discussed

International audienceToday's infrared focal plane arrays concentrate in a small volume of typically 1 cm3 the results of three decades of research in microelectronics and packaging. Several technological breakthroughs have already been achieved leading to the development of infrared focal plane arrays (IRFPA's) for high-performances applications requiring spatial and thermal resolution, also for low-cost and high-manufacturing volumes (technology of uncooled micro-bolometers). The next step is to reduce the optics and make it compatible with the successful IRFPA's fabrication technology. This paper presents some methods and technologies we are exploring for high-performance and small infrared systems. These developments have led to a tool box of micro-concepts described by an optical function (imagery or spectrometry) integrated in the vicinity of the IRFPA. For this, old optical concepts have been revisited (pinhole optics, Talbot effect) and first demonstrations of original IRFPA-based micro-optical assemblies will be given

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