Mr. Alex Paquet Profile

Alex Paquet

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Publications (6)

Proceedings Article | 12 April 2021 Presentation + Paper

On the resolution characterization of THz and MMW FPA-based active imaging systems

François Berthiaume, Alex Paquet, Michel Doucet, Frédéric Emond, Linda Marchese

Proceedings Volume 11745, 117450J (2021) https://doi.org/10.1117/12.2587508

KEYWORDS: Terahertz radiation, Point spread functions, Imaging systems, Contrast transfer function, Modulation transfer functions, Image resolution, Diffraction, Cameras, Reflectors, Spatial frequencies

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Proceedings Article | 20 September 2020 Presentation + Paper

Terahertz imaging of large objects with high resolution

Helene Spisser, Samuel Ouellet, Carl Vachon, Marc Terroux, Martin Briand, François Berthiaume, Michel Doucet, Alex Paquet, Hassane Oulachgar, Francis Genereux, Linda Marchese

Proceedings Volume 11541, 1154106 (2020) https://doi.org/10.1117/12.2574297

KEYWORDS: Image resolution, Terahertz radiation, Millimeter wave imaging, Microbolometers, Imaging systems, Indium oxide, Sensors, Infrared imaging, Infrared radiation, Cameras

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For over 28 years, INO has been developing microbolometer arrays for the infrared and Terahertz (THz) domains. INO’s microbolometer array is the key component of INO’s broadband THz cameras. Using this detector, INO has developed active Terahertz imaging systems ranging from 250 GHz to 750 GHz. See-through THz imaging is particularly well suited for security screening of persons and non-destructive inspection of objects. Materials such as cardboard, plastic, leather and denim are transparent to THz radiation and can provide insights on objects hidden from the naked eye or from infrared cameras. In addition, Terahertz provides high resolution images and is non ionizing. In particular, the frequency range of 150 – 550 GHz is of interest for its properties of see-through imaging that enable a wide variety of potential applications. In this paper, we present images obtained around 400 GHz and 200 GHz (corresponding to wavelengths of 0.76 mm and 1.52 mm). We have chosen these two wavelengths to allow for a wide range of objects and obscuring materials to be tested. The 400 GHz wavelength allows better image resolution, while the 200 GHz provides better penetration through the materials. The THz imaging system can obtain images of objects with dimensions up to 1 meter x 0.75 meter with subcentimeter resolution. To achieve this, we use diffraction-limited imaging optics with high numerical aperture and a microbolometer array detector. For each object, multiple images are acquired that are then stitched together. Each instantaneous image can be seen in real-time during the acquisition and has the same resolution as the global reconstructed image. In the context of an application, the operator does not need to wait until the scan has been completed to identify a hidden object if the size of its features is compatible with the instantaneous field-of-view. When a more global image is required, the reconstructed image shows the features of the whole object under investigation without resolution loss. Images are acquired in two different configurations: transmission and reflection. Each imaging configuration provides different information about the features inside the object as well as its composition. In summary, this paper demonstrates the potential for our THz imaging systems by providing see-through high-resolution THz images of large objects. An analysis of the impact of wavelength and imaging configuration on the image results is also provided.

Proceedings Article | 14 March 2016 Paper

Novel spot size converter for coupling standard single mode fibers to SOI waveguides

Marco Michele Sisto, Bruno Fisette, Jacques-Edmond Paultre, Alex Paquet, Yan Desroches

Proceedings Volume 9752, 975217 (2016) https://doi.org/10.1117/12.2230739

KEYWORDS: Waveguides, Single mode fibers, Tolerancing, Microfabrication, Computer simulations, Silica, Cladding, Error analysis, Beam mode converters, Silicon, Plasma enhanced chemical vapor deposition, Optical alignment, Refractive index

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Proceedings Article | 9 March 2013 Paper

Influence of ceramic package internal components on the performance of vacuum sealed uncooled bolometric detectors

Alex Paquet, Sébastien Deshaies, Yan Desroches, Jeff Whalin, Patrice Topart

Proceedings Volume 8614, 86140G (2013) https://doi.org/10.1117/12.2005945

KEYWORDS: Packaging, Silicon, Epoxies, Indium oxide, Sensors, Adhesives, Ceramics, Carbon dioxide, Reliability, Staring arrays

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Proceedings Article | 29 December 2003 Paper

Si3N4-based photonic crystal membranes

Samir Ilias, Bruno Bourliguet, Claude Pare, Alex Paquet, Christine Alain, Hubert Jerominek

Proceedings Volume 5347, (2003) https://doi.org/10.1117/12.530314

KEYWORDS: Photonic crystals, Silicon, Reactive ion etching, Refractive index, Waveguides, Electron beam lithography, Etching, Photomasks, Polymethylmethacrylate, Plasma

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Proceedings Article | 22 September 2003 Paper

Fingerprint recording with bolometric detectors

Loic Le Noc, Francis Picard, Hubert Jerominek, Christine Alain, Timothy Pope, Patrice Topart, Jerome Godbout, Carol Grenier, Yan Desroches, Anne Martel, Felix Cayer, Patrick Mailloux

Proceedings Volume 5071, (2003) https://doi.org/10.1117/12.487886

KEYWORDS: Sensors, Image sensors, Temperature metrology, Electronics, Infrared sensors, Infrared imaging, Image resolution, Diffusion, Calibration, Resistance

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Modified thermal sensors have been produced and characterized for fingerprint recording applications. The sensors are derived from the IR imaging technology developed at INO. The sensor array is made of 160x120 pixel VO_x based micro thermistors that provide an image of a surface area of 8.3 x 6.2 mm² with a resolution of 488 dpi. The sensors were reinforced to withstand the mechanical pressure of the finger and the electrical discharges from the human skin. It is shown that despite their low thermal insulation, the sensors provide an image of the fingerprint pattern with relatively high contrast and resolution. With the acquisition electronics of an IR imager, the temprature of the sensor must be controlled. Measurements of the thermistor temperature were performed in order to access the intrinsic properties of the fingerprint sensors. The NETD is on the order of 2 10^-3°C when the pass band of the filter is 330 kHz. The temporal behavior of the thermistor temperature shows that 10 ms after the finger has been brought into contact, with the sensor, the temperature difference between thermistors in ridge and valley areas of the fingerprint DT_r,v may reach 80 10^-3°C, for an initial temperature difference between the finger and the sensor of 1°C. Once the sensor reaches a steady thermal state after a long time, the same difference decreases to 1.9 10^-3°C. The required temperature difference DT_r,v, estimated to be 4.8 10^-3°C to achieve an adequate signal to noise ratio, is relatively easy to reach at short and at long time periods. A modification to the method of acquisition is proposed to cancel the effect of the thermal drift of the sensor and to eliminate the need for the sensor temperature stabilization with a TEC. With this method, the recording of the fingerprint pattern may be achieved in 50 ms after the finger has been brought into contact. This leads to interesting gains in space, time and power consumption. Finally, for applications where the finger must remain in contact with the sensor, the same method may be efficient to reduce the need for thermal control.

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