We report on a novel 2 μm laser transmitter for CO2 DIAL, based on a nanosecond parametric master oscillator-power
amplifier architecture. The master oscillator is an entangled-cavity, doubly resonant, optical parametric oscillator, based
on a type-II periodically poled Lithium Niobate nonlinear crystal. This device provides single-longitudinal-mode
radiation, with a high frequency stability and high beam quality, with no need of an additional seeding source. The 2.05
μm signal emission is amplified by multi-stage parametric amplifiers to generate more than 10 mJ. After amplification,
both the spectral purity and beam quality are maintained: we demonstrate single-longitudinal-mode emission with a
frequency stability better than 3 MHz rms, within a nearly diffraction limited beam, with a M2 quality factor close to 1.5.
The unique performances of this parametric architecture make this device a relevant transmitter for CO2 differential-absorption
LIDAR. Such approach could be readily duplicated for the detection of other greenhouse gases.
In this article we address the design and exploitation of a real field laboratory demonstrator combining active
polarimetric and multispectral modes in a single acquisition. Its buildings blocks, including a multi-wavelength
pulsed optical parametric oscillator at emission side, and a hyperspectral imager with polarimetric capability at
reception side, are described. The results obtained with this demonstrator are illustrated on some examples and
A compact laboratory demonstrator providing both active polarimetric and multispectral images is designed. Its
buildings blocks include, at emission part, a multi-wavelength optical parametric oscillator and, at the reception part, a
polarimetric hyperspectral imager. Some of the results obtained with this system are illustrated and discussed. In
particular, we show that a multispectral polarimetric image brings additional information on the scene, especially when
interpreted in conjunction with its counterpart intensity image, since these two images are complementary in most cases.
Moreover, although hyperspectral imaging might be mandatory for recognition of small targets, we evidence that the
number of channels can be limited to a set of few wavelengths as far as target detection is considered.
Bruises can be important evidence in legal medicine, for example in cases of child abuse. Optical techniques can be used to discriminate and quantify the chromophores present in bruised skin, and thereby aid dating of an injury. However, spectroscopic techniques provide only average chromophore concentrations for the sampled volume,
and contain little information about the spatial chromophore distribution in the bruise. Hyperspectral imaging combines the power of imaging and spectroscopy, and can provide both spectroscopic and spatial information. In this study a hyperspectral imaging system developed by Norsk Elektro Optikk AS was used to measure the
temporal development of bruised skin in a human volunteer. The bruises were inflicted by paintball bullets. The wavelength ranges used were 400 - 1000 nm (VNIR) and 900 - 1700 nm (SWIR), and the spectral sampling intervals were 3.7 and 5 nm, respectively. Preliminary results show good spatial discrimination of the bruised
areas compared to normal skin. Development of a white spot can be seen in the central zone of the bruises. This central white zone was found to resemble the shape of the object hitting the skin, and is believed to develop in areas where the impact caused vessel damage. These results show that hyperspectral imaging is a promising
technique to evaluate the temporal and spatial development of bruises on human skin.