MILD: a laser altimeter transmitter for a Mercury planetary orbiter

We report on the design and preliminary development of a micro laser (MILD) breadboard (BB). The laser source is designed to be used as the transmitter unit of a laser altimeter for planetary investigations. The reference scenario is the ESA BepiColombo mission to Mercury (presently scheduled to be launched in 2012) but possible applications to minor solar system bodies may be included. In order to fulfil the laser source requirements for this kind of application we adopted a master-oscillator-power-amplifier (MOPA) scheme. Analysis of the MO efficiency, pulse duration and beam characterisation in different resonator configurations is described together with the preliminary PA performance on a ± 10 °C temperature range. PACS  42.55.Xi; 42.60.By; 42.60.Da     

Optical quality measurements on beams generated by a stable multipass resonator and a hybrid stable–unstable resonator

Using the same radio-frequency excited slab device, we have comparatively studied two different optical schemes defining a stable multipass resonator and a hybrid stable–unstable resonator. A thorough analysis of the beams extracted from the two laser setups shows that the stable folded resonator can produce a quasi-TEM₀₀ output, at a variance with the hybrid stable–unstable resonator which always generates undesired low-power side lobes.     

Pulse behaviour of a compact RF discharged CO2 slab laser

We present the measurements made on a medium power, 35 cm long, radio-frequency discharge CO₂ slab laser operated in a pulsed regime obtained by switching the RF discharge. In this way, pulses with peak power up to 480 W at pulse repetition frequencies in the range 1 to 10 kHz have been obtained. Pulse energy and average extracted power have been experimentally characterized with respect to the pulse repetition frequency and to the pulse duration, and the pulse shape and characteristic times have been measured. We also investigated the propagation properties of the beam emerging from our laser.     

Propagation parameters of the beam extracted from a diode pumped Nd:YAG ceramic slab laser with a hybrid stable–unstable resonator

We analyze the propagation properties of the beam extracted from a diode pumped ceramic Nd:YAG slab laser adopting a hybrid stable–unstable resonator. Such a resonator produces a beam characterized by an Hermite–Gauss mixture-like distribution in one transverse direction and a hard-edge diffracted distribution on the other transverse direction. The beam propagation parameters M_x² and M_y² are measured for different values of the diodes driving current. We obtain a beam parameter product smaller than 3 mm mrad in both transverse directions and in the whole range of powers, up to an extraction of 220 W in a QCW regime.     

An effective procedure for feature subset selection in logistic regression based on information criteria

Computational Optimization and Applications - In this paper, the problem of best subset selection in logistic regression is addressed. In particular, we take into account formulations of the...