Project: Development of an innovative active laser illuminator system based on a medium _x000D_ wavelength infrared laser device.

The project aims to the development of an active imaging system based on a Mid-Wave InfraRed (MWIR) laser system an Imaging Optics and a Focal Plane Array (FPA).The scene is illuminated by a powerful laser source and the backscattered light is collected by an imaging optics and focused onto a suitable matrix of sensors.In free-space laser applications three factors determine the feasibility and effectiveness of a device: the transmission capability of the chosen laser wavelength through the atmosphere, the availability of suitable laser sources and the maturity of sensor technology.For any application in which it is possible anyone's eyes to be exposed to the laser beam, eye safety should also be considered.A major consideration, which becomes more demanding as the operating range increases, is that sufficient power can be delivered through the atmosphere to perform the desired function.Two of the factors that determine whether or not sufficient optical power can be delivered are the absorption and scattering of laser radiation by the molecules/particles lying along the free-space path.Among the spectral bands from the visible to the infrared the most interesting for free space laser applications is the MWIR window around 4um where a minimum in the molecular absorption is found and the scattering from rain and light fog is greatly reduced with respect to lower wavelength bands.Moreover, eye-safety in the MWIR band is guaranteed for the typical laser power densities to be employed.One of the key technological issues of the project consists in the development of a compact and reliable MWIR laser source with sufficiently high pulse energy for illumination over a free-space path several kilometers long.Recent studies demonstrate the possibility to sustain atomic level inversion for MWIR laser action in rare-earth doped crystals.In this wavelength range the best candidate between trivalent Rare Earth elements is Ho3+, that allows an efficient emission near 4 µm.In order to obtain pulsed high power laser emission the choice of the host and the dopant concentration are most important.Indeed, the energy gap of the laser transition of interest is as low as 2500cm-1 thus being easily bridged by non-radiative processes.Then to avoid luminescence quenching via multiphonon relaxation the host material must have a low phonon frequency, a requirement which leads to discard the oxyde hosts in favour of the fluoride ones.The recent technological improvements in the development of reliable high power laser diodes make the efficient pumping of such active crystals an achievable task.NANO will be responsible for the study and the growth of state of art rare earth doped crystals for the MWIR laser system due to its expertise in the field, while DILAS will put its experience to the design and development of the diode modules to pump the active crystal at a non commercial wavelength.GEM will be responsible for the laser source design and development, by paying a special attention to the minimization of the thermal loading inside the crystal which could compromise the laser performances at high power levels.Moreover, GEM will work onthe assembly and test of the whole MILES system in all of its optical, electronical and mechanical aspects.On the other hand, the effective imaging of the small amount of light power backscattered by the illuminated area requires a powerful collecting optics and a high sensitivity detector.The imaging optics, designed with zoom lenses to view illuminated areas over a broad range of distances and employing special materials with high transmittivity in the MWIR spectral band of interest, will be designed and developed by AVASHA , which is a smart and high valued company able to find the finest technological solution to the problem.Imaging in the MWIR spectral band relies currently on HgCdTe (MCT) or InSb focal plane arrays. which have however some shortcomings: InSb based FPA’s are very uniform and give a defect free image but need to operate at ~80K. MCT on the other hand operates typically around ~110 K but suffers from more inhomogeneous material and worse operability.The alternative we propose is T2SL, antimonide based type 2 super lattice which has the potential of reaching even higher operating temperatures than MCT whilst COtaining the uniformity and stability of InSb.IRNOVA will contribute to the sensor development with its experience in the growth of III-V layers and its knowledge in infrared detector processing while XENICS will introduce its experience in interfacing detectors and designing ROIC’s as well as its know-how in camera design and manufacturing.Thus the consortium will be created by Ps which are leading the worldwide research activities about those issues considered strategic for the project.A so comprehensive and versatile system could be employed in several civilian applications belonging to the market of surveillance and homeland security, as described in section 2.3.1

Acronym MILES (Reference Number: 6882)
Duration 29/05/2012 - 31/05/2016
Project Topic The project aims to the development of an active imaging system with (pulsed) laser illumination. The core technology consists of a compact and efficient diode pumped laser working in the MWIR high transmission spectral band, a high sensitivity focal plane array camera and a variable zoom telescope
Network Eurostars
Call Eurostars Cut-Off 7

Project partner

Number Name Role Country
6 XENICS nv Partner Belgium
6 G.E.M. Elettronica s.r.l. Coordinator Italy
6 Istituto Nanoscienze CNR Partner Italy
6 DILAS Diodenlaser GmbH Partner Germany
6 IRnova AB Partner Sweden
6 Avasha AG Partner Switzerland