Search

Active imaging techniques have been, and will remain relevant as an integral part of the sensor network needed in mobile robotics navigation, most commonly with the use of LiDARs. For close range applications, time-of-flight (TOF) cameras are an alternative to more expensive LiDARs. The Kinect v2 (Kinect for XboxOne) has been used frequently as a range imaging camera in machine vision research because of its low cost and good performance. For mobile robotics applications moving at low speed, a larger field of view than the original (70° X 60°) would be desirable to increase awareness of the surroundings, and also detect other moving objects in the trajectory. Our main goal is therefore to increase the Kinect v2 field of view while keeping its main feature of depth measurements. A simple but effective solution consists in using a conversion lens to increase the ray collection angle before the rays enter the IR camera. Depth measurements remain possible from each pixel using TOF with the Kinect v2 modulated signal, provided the field of illumination matches the field of view. A trade-off has to be made between accuracy of depth measurement, optical performance and field of view/illumination enhancement. Therefore, we modified a Kinect v2 to characterize its optical performances and evaluate its relevancy for applications requiring accurate knowledge of the 3D surroundings. A field of view improvement of the Kinect v2 and other similar TOF cameras could offer an alternative at minimal cost for depth measurements in machine vision, specifically in mobile robotics research where object detection and mapping tasks are frequently carried out.

The Photonic Games are a yearly outreach event created in 2008 to spark teenagers’ interest in light. In teams, high school students face several optics challenges designed to appeal to various abilities and interests. In the past 10 years, more than 1531 participants, 425 volunteers and 100 organizers have taken part in this unique student-organized activity. Following the 10th edition, past presidents took the time to reflect together on what they learnt from their experience and identified key elements explaining the long-lasting success of this initiative. Metrics have been defined to track the evolution of the activity’s efficiency and are presented herein.

We have developed a prototype of a low-cost and versatile 3D-printed perfusion chamber for digital holographic microscopy (DHM) of primary neurons in culture. The imaging chamber is 3D-printed in biocompatible plastic. It is easily convertible between a closed configuration, for refractive index - cellular thickness decoupling, and an open configuration, for electrophysiology. In the closed arrangement, the imaging volume is small, allowing a rapid laminar flow with a fast turnover for an optimal implementation of the decoupling procedure. This paper highlights especially the challenges faced while designing and prototyping the 3D-printed closed perfusion chamber with a small imaging volume for DHM. As all 3D-printed mechanical parts were initially leaking because of internal porosities, we developed a simple sealing protocol using acetone vapors to smooth surfaces. Using this protocol, almost all mechanical parts were successfully sealed. Therefore, the production process of the actual prototype, i.e. the 3D printing and the sealing method, is satisfactory for our target application in the field of microfluidics.

We developed a low-cost and versatile 3D-printed perfusion chamber for quantitative phase imaging of primary neurons in culture. The chamber is easily convertible from a closed configuration for decoupling, to an open arrangement for electrophysiology.

For stereoscopic systems designed for metrology applications, the accuracy of camera calibration dictates the precision of the 3D reconstruction. In this paper, the impact of various calibration conditions on the reconstruction quality is studied using a virtual camera calibration technique and the design file of a commercially available lens. This technique enables the study of the statistical behavior of the reconstruction task in selected calibration conditions. The data show that the mean reprojection error should not always be used to evaluate the performance of the calibration process and that a low quality of feature detection does not always lead to a high mean reconstruction error.

Camera calibration is essential for any optical system used to obtain 3D measurements from images. The precision of the 3D depth estimation relies on an appropriate camera model and the accurate estimation of model parameters. These parameters are sensitive to environmental conditions and it is well established that a vision system should be calibrated in operating conditions. This is not always possible since the calibration process is often tedious and time-consuming. Unfortunately, the use of poorly estimated calibration parameters for 3D reconstruction and measurements may lead to suboptimal performance of the system and inaccurate depth estimation. This paper presents a technique using an existing camera model and optical design software to perform calibration simulations. This virtual calibration technique allows for a study of the impact of environmental conditions on the calibration parameters. Using this procedure, it is also possible to predict the statistical behavior of the calibration parameters considering the chosen fabrication processes and tolerances. It can assist vision scientists in the choice of the optical system that best meets the requested precision of the 3D reconstruction. This technique could eventually be integrated in the lens design process to create more reliable optical systems that could be calibrated and used in a range of environmental conditions with a very small variation of their calibration parameters.

Young people often have biased and pre-conceived ideas about scientists and engineers that can dissuade them from considering a career in optics. This situation is compounded by the fact that existing resources on careers in optics are not suitable since they mostly focus on more general occupations such as a physicist and an electrical engineer. In addition, the linguistic register is not adapted for students, and many of these resources are only available to guidance counselors. To create appropriate resources that will inform high school students on different career opportunities in optics and photonics, we sought the collaboration of our local optics community. We selected seven specific occupations: entrepreneur in optics, university professor, teacher, technician, research and development engineer, sales representative and graduate student in optics. For each career, a list of daily tasks was created from the existing documentation by a guidance counselor and was validated by an expert working in the field of optics. Following a process of validation, we built surveys in which professionals were asked to select the tasks that best represented their occupation. The surveys were also used to gather other information such as level of education and advice for young people wishing to pursue careers in optics. Over 175 professionals answered the surveys. With these results, we created a leaflet and career cards that are available online and depict the activities of people working in optics and photonics. We hope that these resources will help counter the negative bias against scientific careers and inform teenagers and young adults on making career choices that are better suited to their preferences and aspirations.

Camera calibration is a critical step in many vision applications. It is a delicate and complex process that is highly sensitive to environmental conditions. This paper presents a novel virtual calibration technique that can be used to study the impact of various factors on the calibration parameters. To highlight the possibilities of the method, the calibration parameters' behavior has been studied regarding the effects of tolerancing and temperature for a specific lens. This technique could also be used in many other promising areas to make calibration in the laboratory or in the field easier.