Pierre Galarneau

Moment definition of the pointing stability of a laser beam

A new definition of the pointing stability of a laser beam is proposed. It is derived from the superposition integral between the optical field and a misaligned version of itself. This approach permits the characterization of the pointing stability with a single number, while taking into account the intensity and phase features of the beam. This pointing stability criterion is invariant under propagation and can be related to the moment definitions of beam size, divergence, and quality. The definition is also suggestive of an experimental measurement procedure.

Diffraction efficiency of a thin amplitude-phase holographic grating : a convolution approach

Abstract The diffraction efficiency of a thin amplitude-phase holographic grating can be determined by a convolution operation of the diffracted amplitude series of both pure-amplitude and pure-phase gratings. Some examples of calculations are presented.

Modeling of an active TV system for surveillance operations

Night vision capability has become an indispensable tool for military and civilian surveillance operations. Low-light- level television (LLLTV) and Forward-Looking-IR (FLIR) devices have long been used for these applications. Nevertheless, both have their shortcomings when the identification of the target is essential for the success of the mission. LLLTV cannot provide god image resolution in ultra low-light level conditions and is very sensitivity to parasitic light. FLIR system have poor resolution when the temperature difference contrast conditions are not met.

Degenerate n-wave mixing in a saturable absorber

A model is developed for the analysis of degenerate n-wave mixing in a saturable absorber, using holographic and nonlinear models simultaneously. The model is applied to both stationary and transient regimes. An experimental verification of the presence of a mixing of the gratings predicted by our model is also presented.

Dynamic and polychromatic SPR-leaky mode spectroscopy with Teflon AF films on silver for chemo-sensing

The reflectivity of a polymer film on top of a thin metal layer is usually recorded for a fixed wavelength and the TM polarization as a function of the angle of incidence. This angular spectrum contains the surface plasmon resonance due to the metal layer and the leaky modes caused by the waveguide resonances of the polymer film. Here we investigated the reflectivity spectrum of such a multilayer for a white light source as a function of the wavelength at a constant angle of incidence. The leaky mode resonances on the wavelength scale have been detected. Dynamic measurements of the reflectivity of such a multilayer at constant angle and constant wavelength have been demonstrated for vapors of Toluene as an example. The realization of compact and simple devices using this technique is possible.

P(VDF-TrFE) infrared detectors and array

Properties of P(VDF-TrFE) copolymer have been studied. A characterization for thermal detection has been done on various copolymer samples with thicknesses ranging from 1 micrometers to 1 mm. a pyroelectric coefficient of 4 nC/cm2 degree(s)C has been measured on samples polarized by the corona discharge method. Optical, dielectric, and thermal properties have also been measured. The possibility of polarizing the copolymer directly on an integrated circuit by corona discharge has been demonstrated and a monolithic detector array of 32 elements has been realized. Fabrication procedure, results of characterization and performance of the detectors are presented.

Closed loop adaptive system with Hartmann wavefront sensor for CO 2 laser radiation correction

Summary form only given: In this paper we consider the design and realization of wide aperture adaptive system to correct for high power CW CO2 laser radiation. Two new approaches for development of the wavefront sensors to measure 10 μ laser radiation are considered.

New Hartmann wavefront sensor for high power CO2 lasers

This paper presents the two types of Hartmann wavefront sensors to measure the aberrations of CO2 laser radiation. One sensor is baser on commercially available IR camera while the second one - on so-called thing film sensors. We discuss both positive and negative attributes of these sensors and the possibility to use them in the real laser systems.

Influence of different laser operation regimes on the specific energy required for rock removal in oil and gas well drilling applications

Although many practical hurdles remain to be addressed in the future, laser oil and gas well drilling has potential advantages over the conventional rotary drilling approach, such as a smaller footprint of the drilling rig, higher rates of penetration, reduction of downtime due to dull bits, reduction of waste caused by drilling mud, creation of a natural casing while drilling, and ability to drill in hard rock formations. One of the most promising applications is downhole laser perforation for well completion as an alternative to explosive technologies currently in use. In order to establish both the technical and economic feasibility of using lasers in oil and gas drilling operations, one can measure the laser energy required to remove a unit volume of rock. The resulting specific energy is a measure of the efficiency of the laser drilling process and depends on the rock type and the laser operation regime that determines the laser-rock interaction mechanism. In the present feasibility study, we compare the results of laser drilling tests conducted in two types of reservoir rocks, namely limestone and sandstone, at different laser wavelengths and for different laser operation regimes (continuous wave and pulsed regimes, different repetition rates and duty cycles) in terms of specific energy. We also discuss preliminary results on the influence of the temporal shape of the laser pulses in the nanosecond regime on the rock removal process as obtained with INO pulse-shaping fiber laser platform, with the objective to take advantage of the flexibility and the agility of such a laser source for drilling operations in different rock types.

The INO–Lauralco hydrogen fluoride monitoring programme: an overview

Abstract Over the last six years, INO and Lauralco have conducted an R&D programme aimed at monitoring, in real-time, hydrogen fluoride emission from both air purification stacks and potroom roof vents of aluminium smelters. The three wavelengths non-dispersive infrared implemented approach has allowed to achieved resolution as small as 0.1 mg/m3 for 10-m optical path length. Long term in situ trials have demonstrated the system compatibility with industrial needs such as ruggedness to various atmospheric conditions and harsh environment, ease of use and very low maintenance cost.