Daniel Cantin

Laser drilling and routing in optical fibers and tapered micropipettes using excimer, femtosecond, and CO2 lasers

We used an excimer laser (193 nm), a femtosecond laser (775 nm) and a CO2 laser (10.6 µm) to drill cylindrical holes in fused silica optical fibers and in glass micro-pipettes. CO2 laser-drilling using tip processing results in tapered holes with larger diameters than the holes drilled with the excimer and the femtosecond laser. Although routing of holes of various shapes results in sharper edges and a higher aspect ratio when the femtosecond laser is used, the CO2 laser could still be used to route rectangular holes in fused silica optical fibers. Albeit hole dimensions and details are smaller when micromachined with the excimer and the femtosecond lasers, the optical fibers are very brittle at the end of the process. CO2 lasers offer the advantage of producing higher fused silica ablation rates with much better polished surfaces and a better mechanical integrity, which are usually more suitable in some applications.

Latest developments in active remote sensing at INO

Remote sensing or stand-off detection using controlled light sources is a well known and often used technique for atmospheric and surface spatial mapping. Today, ground based, vehicle-borne and airborne systems are able to cover large areas with high accuracy and good reliability. This kind of detection based on LiDAR (Light Detection and Ranging) or active Differential Optical Absorption Spectroscopy (DOAS) technologies, measures optical responses from controlled illumination of targets. Properties that can be recorded include volume back-scattering, surface reflectivity, molecular absorption, induced fluorescence and Raman scattering. The various elastic and inelastic backscattering responses allow the identification or characterization of content of the target volumes or surfaces. INO has developed instrumentations to measure distance to solid targets and monitor particles suspended in the air or in water in real time. Our full waveform LiDAR system is designed for use in numerous applications in environmental or process monitoring such as dust detection systems, aerosol (pesticide) drift monitoring, liquid level sensing or underwater bathymetric LiDARs. Our gated imaging developments are used as aids in visibility enhancement or in remote sensing spectroscopy. Furthermore, when coupled with a spectrograph having a large number of channels, the technique becomes active multispectral/hyperspectral detection or imaging allowing measurement of ultra-violet laser induced fluorescence (UV LIF), time resolved fluorescence (in the ns to ms range) as well as gated Raman spectroscopy. These latter techniques make possible the stand-off detection of bio-aerosols, drugs, explosives as well as the identification of mineral content for geological survey. This paper reviews the latest technology developments in active remote sensing at INO and presents on-going projects conducted to address future applications in environmental monitoring.

Active 3D camera design for target capture on Mars orbit

During the ESA Mars Sample Return (MSR) mission, a sample canister launched from Mars will be autonomously captured by an orbiting satellite. We present the concept and the design of an active 3D camera supporting the orbiter navigation system during the rendezvous and capture phase. This camera aims at providing the range and bearing of a 20 cm diameter canister from 2 m to 5 km within a 20° field-of-view without moving parts (scannerless). The concept exploits the sensitivity and the gating capability of a gated intensified camera. It is supported by a pulsed source based on an array of laser diodes with adjustable amplitude and pulse duration (from nanoseconds to microseconds). The ranging capability is obtained by adequately controlling the timing between the acquisition of 2D images and the emission of the light pulses. Three modes of acquisition are identified to accommodate the different levels of ranging and bearing accuracy and the 3D data refresh rate. To come up with a single 3D image, each mode requires a different number of images to be processed. These modes can be applied to the different approach phases. The entire concept of operation of this camera is detailed with an emphasis on the extreme lighting conditions. Its uses for other space missions and terrestrial applications are also highlighted. This design is implemented in a prototype with shorter ranging capabilities for concept validation. Preliminary results obtained with this prototype are also presented. This work is financed by the Canadian Space Agency.

BioSense/SR-BioSpectra demonstrations of wide area/early warning for bioaerosol threats: program description and early test and evaluation results

Threats associated with bioaerosol weapons have been around for several decades and have been mostly associated with terrorist activities or rogue nations. Up to the turn of the millennium, defence concepts against such menaces relied mainly on point or in-situ detection technologies. Over the last 10 years, significant efforts have been deployed by multiple countries to supplement the limited spatial coverage of a network of one or more point bio-detectors using lidar technology. The addition of such technology makes it possible to detect within seconds suspect aerosol clouds over area of several tens of square kilometers and track their trajectories. These additional capabilities are paramount in directing presumptive ID missions, mapping hazardous areas, establishing efficient counter-measures and supporting subsequent forensic investigations. In order to develop such capabilities, Defence Research and Development Canada (DRDC) and the Chemical, Biological, Radiological-Nuclear, and Explosives Research and Technology Initiative (CRTI) have supported two major demonstrations based on spectrally resolved Laser Induced Fluorescence (LIF) lidar: BioSense, aimed at defence military missions in wide open spaces, and SR-BioSpectra, aimed at surveillance of enclosed or semienclosed wide spaces common to defence and public security missions. This article first reviews briefly the modeling behind these demonstration concepts. Second, the lidar-adapted and the benchtop bioaerosol LIF chambers (BSL1), developed to challenge the constructed detection systems and to accelerate the population of the library of spectral LIF properties of bioaerosols and interferents of interest, will be described. Next, the most recent test and evaluation (T&E) results obtained with SR-BioSpectra and BioSense are reported. Finally, a brief discussion stating the way ahead for a complete defence suite is provided.

Novel applications of an affordable short-range digital lidar

The design and application results of an affordable short range (less than 100 m) digital LIDAR (LIght Detection And Ranging) system will be presented. This work was initiated because many short-range standoff detection applications would benefit from such a system. The lidar features a fiber-based component integrated in the optical module, which allows for hardware partial compensation of the backscattered signal losses observed at short distances due to a biaxial configuration of the lidar optics. This is an important advantage for particle density computations. The digitized backscattered laser signals are available for signal processing. A dedicated FPGA (Field Programmable Gate Array) allows for real-time averaging of the signal waveforms captured at the maximum 50-kHz pulse repetition frequency of the laser. Several application-specific tests have been performed. The first of these was real-time onboard monitoring of pesticide drift in agricultural spraying applications. The signal levels were sufficient for control of the spraying operations and prevention of pesticide drift into sensitive areas. The second was a dust monitoring application. The lidar was installed in a quarry and signals from dust clouds were recorded. Real-time monitoring capabilities were shown to be promising. Other applications involving detection of solid targets in degraded visibility conditions caused by fog or snowfalls were also tested and are discussed.

Fiber laser pumped tunable Cr2+:ZnSe laser

A 2.4 μm room-temperature continuous-wave Cr2+:ZnSe laser pumped by a Thulium Fiber Laser is experimentally investigated. The laser delivers up to 720 mW of output power with absorbed power slope efficiency of 52%. The laser is tunable from 2294 to 2678 nm. Gain-switching is also demonstrated by using a Pulsed Erbium Fiber Laser pump source. A maximum pulse energy of 0.36 μJ is achieved with an absorbed threshold of 0.28 μJ and an absorbed power slope efficiency of 41%.