We present a widely tunable mid infrared coherent light source based on a tandem optical parametric oscillator (OPO)
and subsequent optical parametric amplification (OPA). The output wavelengths can be seamlessly tuned in the Mid-IR
from 2.6 μm to 12 μm or 4000 cm<sup>-1</sup> to 833 cm<sup>-1</sup> respectively. Maximal output energy of 26 mJ was obtained at a wavelength of 4.25 μm.
This paper will describe ongoing work from an EDA initiated study on Active Imaging with emphasis of using multi or
broadband spectral lasers and receivers. Present laser based imaging and mapping systems are mostly based on a fixed
frequency lasers. On the other hand great progress has recently occurred in passive multi- and hyperspectral imaging
with applications ranging from environmental monitoring and geology to mapping, military surveillance, and
reconnaissance. Data bases on spectral signatures allow the possibility to discriminate between different materials in the
scene. Present multi- and hyperspectral sensors mainly operate in the visible and short wavelength region (0.4-2.5 μm)
and rely on the solar radiation giving shortcoming due to shadows, clouds, illumination angles and lack of night
operation. Active spectral imaging however will largely overcome these difficulties by a complete control of the
illumination. Active illumination enables spectral night and low-light operation beside a robust way of obtaining
polarization and high resolution 2D/3D information.
Recent development of broadband lasers and advanced imaging 3D focal plane arrays has led to new opportunities for
advanced spectral and polarization imaging with high range resolution. Fusing the knowledge of ladar and passive
spectral imaging will result in new capabilities in the field of
EO-sensing to be shown in the study. We will present an
overview of technology, systems and applications for active spectral imaging and propose future activities in connection
with some prioritized applications.
The generation of tunable mid-infrared (MIR) laser radiation in the spectral range from 4 μm to 5 μm by nonlinear
frequency-conversion of laser pulses in periodically poled Lithium niobate (PPLN) is investigated. Results of several
experiments including nanosecond-, picosecond- and femtosecond- laser systems are presented and the potential and
limitations of PPLN as nonlinear material for the MIR frequency-conversion are discussed.
We present the 3D-imaging of a target using range gated laser systems operating at 1.5 μm. Two different illumination
techniques were investigated: 1) a conventional illumination technique consisting of a Raman-shifted Nd:YAG laser with
a fixed wavelength, and 2) a technique which makes use of a wavelength-tunable illumination source consisting of a
Nd:YAG-pumped OPO. We compare the influence of each illumination technique on target induced speckle effects and
the resulting range resolution. Image samples were taken at ranges of up to 2.5 km.