Istituto di Fisica Applicata «Nello Carrara» (IFAC), CNR, Firenze, Italy

The present paper will discuss the work in progress at the Department of Physics of the University of Pisa in collaboration with the IFAC laboratory of CNR in Florence to develop pressure sensors with outstanding sensitivity in the acoustic and ultrasonic ranges. These devices are based on optically-pumped fiber lasers, where the mirrors are Bragg gratings written into the fiber core.

Future trends for the development of new remote sensing imagers have being defined since the launch of the first Fourier Transform HyperSpectral Imager (FTHSI) on board of DoD technological satellite MightySat II.1. Starting from the analysis of FTHSI optical configuration we have proposed an interesting modification which produces an image of the observed surface superimposed to a stationary interference pattern. This new optical arrangement together with the possibility to accommodate the spectral resolution by changing the device optical aperture and the sensor sampling step make the new instrument interesting for Earth remote sensing purposes. In this paper we present some preliminary results obtained from a laboratory prototype developed at our Institute. Some hints are discussed about the use of such an instrument on board of airborne and satellite platforms.

industries. In this paper we introduce the results from a remote sensing campaign performed in September 2001 at night time. For the first time nocturnal light pollution was measured at high spatial and spectral resolution using two airborne hyperspectral sensors, namely the Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) and the Visible InfraRed Scanner (VIRS-200). These imagers, generally employed for day-time Earth remote sensing, were flown over the Tuscany coast (Italy) on board of a Casa 212/200 airplane from an altitude of 1.5-2.0 km. We describe the experimental activities which preceded the remote sensing campaign, the optimization of sensor configuration, and the images as far acquired. The obtained results point out the novelty of the performed measurements and highlight the need to employ advanced remote sensing techniques as a spectroscopic tool for light pollution monitoring.

The definition of noise models suitable for hyperspectral data is slightly different depending on whether whiskbroom or push-broom are dealt with. Focussing on the latter type (e.g., VIRS-200) the noise is intrinsically non-stationary in the raw digital counts. After calibration, i.e. removing the variability effects due to different gains and offsets of detectors, the noise will exhibit stationary statistics, at least spatially. Hence, separable 3D processes correlated across track (x), along track (y) and in the wavelength (λ), modelled as auto-regressive with GG statistics have been found to be adequate. Estimation of model parameters from the true data is accomplished through robust techniques relying on linear regressions calculated on scatter-plots of local statistics. An original procedure was devised to detect areas within the scatter-plot corresponding to statistically homogeneous pixels. Results on VIRS-200 data show that the noise is heavy-tailed (tails longer than those of a Gaussian PDF) and somewhat correlated along and across track by slightly different extents. Spectral correlation has been investigated as well and found to depend both on the sparseness (spectral sampling) and on the wavelength values of the bands that have been selected.