Team

Research team

Denis Brousseau received his PhD in physics from Université Laval in 2008, under the supervision of Professor Ermanno F. Borra. After his doctorate, he joined Prof. Simon Thibault's team at the NSERC Industrial Research Chair in Optical Design at Université Laval as a research professional. Denis Brousseau carries out optical design work of a scientific or industrial nature and participates in the research activities of the Chair. In astronomical instrumentation, he participated in the design, assembly and carried out the tests of the optical components of SITELLE and SPIRou, two instruments for the Canada-France-Hawaii telescope. He developed an optical simulation bench for NIRISS (JWST) and made the optical design of PESTO (OMM) and the KECK laser asterism generator. He has also worked on NIRPS (Near Infra-Red Planet Searcher), an infrared spectrometer for ESO's 3.6m telescope in Chile, and on GIRMOS (Gemini Infrared Multi- Object Spectrograph) for the Gemini Observatory.

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Anne-Sophie Poulin-Girard received her PhD from Université Laval in 2016, under the supervision of Profs. Simon Thibault and Denis Laurendeau. Her thesis focused on the use of panoramic lenses in 3D reconstruction, at the boundary between optical engineering and computer vision. Following her PhD, she became the scientific coordinator of the Canada Excellence Research Chair in Neurophotonics. In 2017, she came back to Prof. Thibault's team as a research associate. She is also responsible of the scientific and technical coordination of the NSERC Industrial chair in optical design. She currently participate in several research and development projects in collaboration with industry, and to assembly, integration and testing phase for the spectrograph of NIRPS, an instrument dedicated to the detection of exoplanets. Passionate about education, she was the chair of SPIE Education committee and has welcomed the international conference SPIE/OSA/IEEE/ICO Education and Training in optics and photonics in 2019 and is the co-chair of Optics Education and Outreach conference at SPIE O+P since 2020. Since 2021, she is also a member of the Natural Sciences and Engineering Research Council of Canada (NSERC).

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Hugues Auger obtained a technical college degree in physics engineering from Cégep de La Pocatière in 1988. He then joined INO as a technician where he participates in all the step of product fabrication, from planification to final inspection. He also trains other employees and is responsible for various equipments and faclities. He is experienced with a variety of specialized equipment and different measurement tools. In 2009, he joined the NSERC Industrial research chair in optical design at Université Laval. His advanced expertise in diffraction optics, lithography, microengraving, microfabrication and characterisation is put to good use. He is also the technician responsible for optical assembly and characterisation lab, and for the optical component fabrication lab.

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Biomimicry is a design philosophy that guides the development of new technologies by taking inspiration from solutions that are developed naturally by living organisms. Many of the problems encountered in engineering are similar to those that can be encountered in nature. The solutions that are found by evolution through natural selection are often unique and move away from those that are already used in engineering.

In the field of optics, it becomes natural to take inspiration from the different ways in which the living world has adapted to use the light that surrounds it. The eyes are an example of specific adaptation of animal species to their way of interacting with the environment. The research project will focus on these solutions by applying them to optical systems for digital vision. In particular, we will focus on the problems in active vision, which uses the movements of the optical system to obtain more information on the scene to be analyzed.

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Description coming soon.

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The wavefront can be tuned by judiciously accumulate the phase through the refractive and diffractive elements of a classical optical system. Recently, the interest in metasurfaces returns as the phase, the amplitude and the polarization can be controlled over only a few microns of distance by exploiting the boundary conditions of small structures constituting the metasurface as an example. However, their use in optical design is still marginal. The optical properties of such surfaces are hard to model as long numerical simulations are needed even in the simple case of a nanofin array. This situation is troublesome to an optical designer as it greatly limits its capacity to determine an optimal combination of optical elements for a given application.

The project scopes to provide an analytical or semi-analytical model to described the surface’s effect upon an incident wavefront. The optical properties could be related to traditional aberration treatment. Thus, the metasurface would be more attractive for an optical designer. The proposed formalism could be generalized to model other metasurfaces. Then, the unique properties of these surfaces could be applied for new applications.

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Optical and detection systems miniaturization is one of the most marked challenges of today’s technological development. High-precision medical equipment, nanosatellites and advanced mobile imaging are only some examples of different applications where optical systems miniaturization is of high interest. Since the second half of the 20th century, unusual materials have entered the optical development equation. These nanostructures possess smaller dimensions than the wave traveling through it, allowing great possibilities regarding phase, amplitude and propagation efficiency manipulation. However, as any emerging technology, the EM metasurface’s properties are still largely unknown and conventional mathematical analysis methods are temporally very costly.

The goal of this project is therefore to establish a theoretical model for two types of nanostructures that make up a metasurface in order to ultimately be able to reduce the complexity of using these two types of nanostructures in an optical design context. An extended analysis of vacuum and thermal effects will then be applied to the theoretical model in order to improve its validity under space tool development conditions or under extreme conditions.

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Wide angle images are characterized by a large field of view (higher than 100°) and are obtained using short focal imaging systems. This large field of view makes them highly interesting for computer vision applications. Learning-based approaches, especially convolutional neural networks, need reference datas to supervise the training process. Such datas are composed of images and annotations such as objects masks, depth maps… Those annotations are hard to collect and most available datasets are made from perspective images which is the most common type of images. However this makes it impossible to use such networks on wide angle images, because of the strong distortion that leads to a drop in network performances. To tackle this issue, wide angle images are generally processed before being used, a time consuming task leading to a loss of field of view.

The democratization of wide angle imaging systems leads to an increase of available datas making them available for network training supervision. The goal of this project is to study the influence of distortion on neural networks taking depth estimation as a case of study. Specifically, we want to estimate if it’s possible to obtain the same accuracy by directly training a network on wide angle images instead of processing them to use pre-trained networks. This would save time and make us able to keep all the information available in such images. For our wide angle images, we used panomorph lenses developed by Immervision company that present a non linear distortion. They use controlled distortion to increase the resolution in a region of interest of the image. The second goal of this project is to determine if we can use such properties to obtain localized improved depth estimation.

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Modern telescopes possess the ability to image multiple stellar objects simultaneously, inside fairly large field of views, requiring large angular resolutions. The spectrographs that are used with those astronomical instruments, however, are limited in resolution by the width of their entry slit, as well as the incident beam’s diameter. To solve this problem, one may reduce the width of the slit by dividing the stellar image at the focal plane of the telescope or dividing the image of the telescope’s entrance pupil to reduce the beam’s effective diameter. These manipulations are made possible by the use of image slicers and pupil slicers, respectively. Such optical systems are traditionally composed of stacks of mirrors placed strategically to decompose the planes of interest in a series of thin slices, arranged in a given number of lines.

This Masters project is comprised in the development of a new infrared spectrograph for the Gemini-South Observatory, called the Gemini Infrared Multi-Object Spectrograph (GIRMOS). GIRMOS is designed to produce high angular-resolution and highly sensitive infrared images of the sky. My role in this project consists of designing an image slicer for this spectrograph, that will divide the telescope’s image plane into a series of thirty sub-images arranged in a single line. The designed optical system must also perform well in all the J, H and K bands of the infrared spectrum. My Masters project also comprises the design of a pupil slicer to be placed before a spectrograph named VROOMM, that will be installed at Mont Mégantic Observatory. It will be used to divide the pupil plane of an optical fiber in two superimposed segments and will operate in the visible light spectrum. Furthermore, my project includes the diamond turning fabrication of mirrors used in the University of Florida’s MIRADAS instrument’s Macro-Slicer, as well as the quality control of their surface.

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Our goal is to develop a new modal wavefront sensor based on photonic crystal and metasurfaces. Photonic crystal structure has been used successfully for amplitude beam shaping to transform a Gaussian beam in Laguerre-Gauss beam or other beam mode. Small structures produce unexpected light behavior that can be used to optimize a modal wavefront sensor. An optimized photonic crystal will allow us to find the information on the wavefront in the Fourier plane. Having a modal wavefront sensor can be advantageous compared to a zonal wavefront sensor such as the Shack-Hartmann, because the reconstruction of the wavefront is much faster if modes are obtained directly (the Zernike polynomials). Modal wavefront sensors already exist; those are usually produced by holography. We think that our approach can be easier to use and less frequency-limiting than holographic wavefront sensor while keeping the advantages of modal wavefront sensor. Finally, we explore how metasurfaces can be used in conjunction with a lens to develop a modal wavefront sensor.

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More details to come.

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The project aims at the design and implementation of a high-resolution optical spectrograph to detect exoplanets (VROOMM). The instrument will measure, with a high precision, radial velocity of nearby bright stars, in particular 1400 in the northern hemisphere, all strongly suspected to host one or several transiting exoplanets. The design will be partially inspired by HARPS (High Accuracy Radial velocity Planet Searcher) and its near infrared version, NIRPS. The project include the design, implementation and integration of the instrument, as well as tests and measures scheduled at the Observatoire du Mont-Mégantic in Fall 2018.

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A stratospheric balloon has the advantage of greatly limiting the atmospheric turbulences which are stronger at ground level, and significantly affects the image quality. Moreover, a balloon allows to save costs in comparison of a space mission where the conditions are more extreme. Stratospheric balloons are an interesting avenue for the astronomic instrumentation’s field, allowing to test technological advancements in space-like conditions for a fraction of the price.

The goal of my master’s degree project is to contribute to the creation of high contrast imaging tools for direct observation of exoplanets in a near future. High contrast imaging consists of blocking the light of an important bright source, like a star, to be able to visualize near planets not visible in other ways. To do so, an optical system with the best possible image quality is necessary. Since atmospheric turbulences disturb every taken pictures, to acquire data on them is essential to correct them in the future.

To achieve my goal, I work on the HiCIBaS-II (High-Contrast Imaging Balloon System) precursor mission. HiCIBaS-II is an atmospheric turbulences measure instrument onboard a stratospheric balloon. The balloon will fly between 36 to 40 km of altitude for a duration of 8 to 10 hours in the night. The instrument launch is planned for the end of summer 2022 at the Timmins’ launch base, in Ontario. My project contribution is to be responsible for the system optical conception.

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Sea ice is composed of super-salty liquid channels, air, ice, microbial organisms and small invertebrates. Inspired by medical endoscopes, Takuvik is developing a miniature platform for measuring important sea ice In situ variables. A microscope will be added to this endoscope to observe living micro-organisms in air bubbles and brine pockets inside the sea ice as well as the ice microstructures. Without disturbing the environment, the endoscope will be used to determine how these organisms thrive inside the sea ice. The challenge of developing an In situ microorganism imaging system are the small consecration, the transparency, the movement and the high resolution essential to the organism identification. This project will consider all these variables to determine the best imaging system.

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Current measurement of snow properties requires manual manipulations. These manipulations are in fact 3 different measurements that scientists need to carefully acquire two optical measurements combined with a density measurement. The goal of this project is to automatize these measurement by measuring all the optical properties of the snow at once. For snow scientists, this project would give them possibilities to monitor snow all year long in the most foreign territories of the world. The device in development uses the fact that snow is a highly scattering media and the radiative transfer in this media depends on the properties of the ice grains constituting the snow and the snowpack itself. The optical properties of snow are influenced by the density of the snowpack, the size of a snow grain and the shape of the grains. The devise will be sending light in the medium and measure the outcomes of that light. Three different outcomes will need to be measured to monitor these properties. Transmittance measurement and albedo measurement are already used to monitor the snow and will also be used in this project, but the most ambitious part of this project is to measure the propagation time of light in the snow. Light’s propagation time will be affected by the density of the snow due to the speed of light that depends on the fraction of it’s path that is traveled in ice and on the length of the path itself. To characterize the propagation time as a function of the different properties of the snow, a ray tracing model is used instead of usual radiative transfer model. This model can give the path lengths and the fraction of the path in ice because snow can be modeled with rays’ optic. With the ray tracing model, a database of propagation times and retro diffusion profiles will be used to invert the properties of the snow from the optical measurements on the field.

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Digital holographic microscopy emerged about twenty years ago and is now used to study samples from many fields covering microelectronics to cellular analysis in a three-dimensional way. However, this technique is deeply exposed to optical aberrations, these image distortions are caused by the imaging systems and need to be controlled at most to obtain images with good quality. On the other hand, digital holography allows the correction of a part of these aberrations during their digital treatment.

This project consists to verify how much these methods of aberration adjustment are effective. This understanding will allow optical designers to widen their criteria during the development of this kind of microscope. That will help to make it more compact, less expensive, and more powerful.

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In recent years, a growing scientific interest in the field of 3D imaging has led to important technological advances in this field. Their applications are numerous and concern the medical, defense and entertainment fields, for example. This research project, through an experimental approach supported by optical design, will provide, in an innovative way, an evaluation of the optical performance of different 3D imaging systems for human vision. In this perspective, two experimental projects will be conducted according to the following method. First, the aim will be to develop an experimental device capable of generating and projecting 3D images. Second, the objective will be to provide an efficient method to evaluate its performances allowing a quantitative analysis of the measurements. Third, we will seek to optimize these performances.

The first experimental project will focus on autostereoscopic 3D displays based on the principle of integral imaging, which allows to form 3D images adapted to human vision without the use of additional tools. Integral imaging uses a matrix of refractive microlenses. Our goal will be to replace it by a matrix of meta-surfaces in order to implement this imaging principle on mobile devices such as cell phones or tablets. The second experimental project will focus on volumetric projection based on two-photon absorption in a cubic matrix containing quantum dots. A three-dimensional laser scan in this matrix will excite these quantum dots and create local illumination in the volume (called voxel). These two aspects of the research project have a strong experimental component and require a design, analysis and characterization phase to optimize optical performances.

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Emission lines coming from HII regions are great in the determination of chemical abundances in galaxies to understand their evolution. These regions of gases ionized by young hot stars also led to the identification of physical process like shocks and photoinization in the interstellar medium. Although, there are great uncertainties associated with the determination of the chemical abundances because of our incomplet understanding of these ionized regions. These regions are strongly complex, and the interaction the gases have with their environment create a complex kinematic. Turbulence becomes a principal actor. Also, depending on the method used to calculate the abundances, the results are not the same. This problem is more than 70 years old and is named the abundance discrepancy problem. Many reasons and hypothesis were brought to try to explain these results : temperature fluctuations, chemical or even density inhomogeneity. Moreover, the majority of the observations appearing in the literature come from classical slit spectroscopy and may be part of the problem with the unidimensionality of the observation method.

This project as for goal to do a thermodynamic analysis of HII regions with the help of bidimensionnal diagnostics maps of physical parameters such as the electron density and electron temperature at small scales to quantify the potential fluctuations of these parameters. Monte-Carlo analysis will be implemented to secure precision on the physical characteristic of the nebula. All of that will be possible with the help of the great spectral and spatial resolution of the SITELLE instrument based at the CFHT to obtain those maps.

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Since the beginning of the Space Race, space debris represent a growing threat; their relative speeds make even the tiniest a potential hazard. With all these objects in space around us, collisions between resident space objects (RSOs) is an inevitable threat and will lead in an exponential growth of the small size (inferior to 10 cm) debris population.

This master's project consists in determining the necessary characteristics for a camera used to detect space debris from a telescope installed on a stratospheric balloon. These characteristics will be determined using a flight simulation done by a former master's student and by comparing CCD, CMOS and EMCCD cameras for an altitude of 36 to 40 km. The student specifies the required altitude, the telescope angle and the observation periods to observe the space debris. The payload for this project is to be selected by the fall of 2022 as the camera will be integrated into the HiCIBaS-II (High-Contrast Imaging Balloon System) telescope when it is launched in Timmins, Ontario.

To achieve these goals, the student contributes to the HiCIBaS-II project, an instrument for measuring atmospheric turbulence embarked on a stratospheric balloon scheduled for launch in September 2023 as the person in charge of the cameras and control of the engines.

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