Spectrum estimation from truncated, non-linearly phase shifted or irregularly sampled interferograms.

For performance or speed reasons, many types of spectrometers record only part of the interferogram thanks to its redundancy. Here we examine the consequences of this choice on the resulting spectrum. We jointly explore other sources of error also encountered on spectrometers, such as the irregular sampling of the interferometer and the non-linear phase of the spectrum.

Theoretical and practical analysis of spatial and spectral calibration of static Fourier transform infrared spectrometers.

Static Fourier transform spectrometers require, especially in the infrared, a spatial calibration step. Unfortunately, the superposition of fringes on the measured images has a major impact on spatial calibration and therefore on the returned spectra. We first study how to pre-process images so that spectral errors are minimized.

SIELETERS, an airborne infrared dual-band spectro-imaging system for measurement of scene spectral signatures.

More and more, hyperspectral images are envisaged to improve the aerial reconnaissance capability of airborne systems, both for civilian and military applications. To confirm the hopes put in this new way of imaging a scene, it is necessary to develop airborne systems allowing the measurement of the spectral signatures of objects of interest in real conditions, with high spectral and spatial resolutions. The purpose of this paper is to present the design and the first in-flight results of the dual-band infrared spectro-imaging system called Sieleters.

Ensuring long-term stability of infrared camera absolute calibration.

Absolute calibration of cryogenic 3-5 µm and 8-10 µm infrared cameras is notoriously instable and thus has to be repeated before actual measurements. Moreover, the signal to noise ratio of the imagery is lowered, decreasing its quality. These performances degradations strongly lessen the suitability of Infrared Imaging.

Relevance of continuously self-imaging gratings for noise robust imagery.

We have designed miniaturized, simple, and robust cameras composed of a single diffractive optical element (DOE) that generates a continuously self-imaging (CSI) beam. Two different DOEs are explored: the J0 Bessel transmittance, characterized by a continuous optical transfer function (OTF) and the CSI grating (CSIG), characterized by a sparse OTF. In this Letter, we will analyze the properties of both DOEs in terms of radiometric performances.

Calibration and validation by professional observers of the Mission-Quality criterion for imaging systems design.

Imaging systems comparisons remains today a sensitive subject because of the difficulty to merge radiometric and spatial dimensions into a single, easy to use, parameter. By leaning explicitly on professional image users and their requirements we show how to build such a criterion, called Mission-Quality. A specific observation campaign is described and its results are used to calibrate and carry first proof of the criterion adequacy.

Demonstration of image-zooming capability for diffractive axicons.

Diffractive axicons are optical components producing achromatic nondiffracting beams. They thus produce a focal line rather than a focal point for classical lenses. This gives the interesting property of a long focal depth.

Radiometric order preserving method to display wide-dynamic images for imagery photointerpretation.

Wide-dynamic numerical images are increasingly frequent in professional environments, military photointerpretation, and x-ray or magnetic resonance medical imagery. However, a dynamic compression process is necessary to exploit such images without incessant image manipulation. A wealth of efficient methods has been developed to tackle this problem on aesthetic grounds.