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.
View Article and Find Full Text PDFOne of the major limitations to the use of infrared focal plane arrays (IRFPAs) in stationary Fourier transform spectrometers (FTSs) comes from the spatial inhomogeneities of the pixel responses, where the inhomogeneities of the cut-off wavenumbers of the pixels can prevail. The hypothesis commonly assumed for FTSs that all the pixels are equivalent is thus inaccurate and results in a degradation of the estimated spectrum, even far from the cut-off wavenumbers. However, if the individual spectral responses of the pixels are measured beforehand, this a priori information can be used in the inversion process to produce reliable spectra.
View Article and Find Full Text PDFA design of a miniaturized stationary Fourier transform IR spectrometer has been developed that produces a two-dimensional interferogram. The latter is disturbed by effects like parasitic interferences or disparities in the cutoff wavelength of the pixels. Thus, a simple Fourier transform cannot be used to estimate the spectrum of the scene.
View Article and Find Full Text PDFWe report nearly perfect optical transmission (87%) through freestanding metallic gratings with narrow slits, as the experimental demonstration of the theoretical prediction by Porto et al. [Phys. Rev.
View Article and Find Full Text PDFWe present an original and compact optical system inspired by the unusual eyes of a Strepsipteran insect called Xenos peckii. It is designed for a field of view of 30 degrees and is composed of multiple telescopes. An array of prisms of various angles is placed in front of these telescopes in order to set a different field of view for each channel.
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