In a typical optical system, optical elements usually need to be precisely positioned and aligned to perform the correct optical function. This positioning and alignment involves securing the optical element in a holder or mount. Proper centering of an optical element with respect to the holder is a delicate operation that generally requires tight manufacturing tolerances or active alignment, resulting in costly optical assemblies. To optimize optical performance and minimize manufacturing cost, there is a need for a lens mounting method that could relax manufacturing tolerance, reduce assembly time and provide high centering accuracy. This paper presents a patent pending lens mounting method developed at INO that can be compared to the drop-in technique for its simplicity while providing the level of accuracy close to that achievable with techniques using a centering machine (usually < 5 µm). This innovative auto-centering method is based on the use of geometrical relationship between the lens diameter, the lens radius of curvature and the thread angle of the retaining ring. The autocentering principle and centering test results performed on real optical assemblies are presented.In addition to the low assembly time, high centering accuracy, and environmental robustness, the INO auto-centering method has the advantage of relaxing lens and barrel bore diameter tolerances as well as lens wedge tolerances. The use of this novel lens mounting method significantly reduces manufacturing and assembly costs for high performance optical systems. Large volume productions would especially benefit from this advancement in precision lens mounting, potentially providing a drastic cost reduction.

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Wavefront sensing is one of the key elements of an Adaptive Optics System. Although Shack-Hartmann WFS are the most commonly used whether for astronomical or biomedical applications, the high-sensitivity and large dynamic-range of the Pyramid-WFS (P-WFS) technology is promising and needs to be further investigated for proper justification in future Extremely Large Telescopes (ELT) applications. At INO, center for applied research in optics and technology transfer in Quebec City, Canada, we have recently set to develop a Pyramid wavefront sensor (P-WFS), an option for which no other research group in Canada had any experience. A first version had been built and tested in 2013 in collaboration with NRC-HIA Victoria. Here we present a second iteration of demonstrator with an extended spectral range, fast modulation capability and low-noise, fast-acquisition EMCCD sensor. The system has been designed with compactness and robustness in mind to allow on-sky testing at Mont Mégantic facility, in parallel with a ShackHartmann sensor so as to compare both options.

Objectives: In Quebec, Canada, we evaluated the risk of SARS-CoV-2 infection associated with: 1) the demographic and employment characteristics among healthcare workers (HCWs); and 2) the workplace and household exposures and the infection prevention and control (IPC) measures among patient-facing HCWs. Design: Test-negative case-control study Setting: Provincial health system Participants: HCWs with PCR-confirmed COVID-19 diagnosed between November 15, 2020 and May 29, 2021 (cases) were compared to HCWs with compatible symptoms but testing negative during the same period (controls). Methods: Adjusted odds ratios (aOR) of infection were estimated using regression logistic models evaluating demographic and employment characteristics (all 4919 cases and 4803 controls) or household and workplace exposures and IPC measures (2046 patient-facing cases and 1362 controls). Results: COVID-19 risk was associated with working as housekeeping staff (aOR=3.6), patient support assistants (aOR=1.9) and nursing staff (aOR=1.4) (compared to administrative staff), being unexperienced (aOR=1.5) and working in private seniors’ homes (aOR=2.1) and long-term care (aOR=1.5) facilities (compared to acute-care hospitals). Among patient-facing HCWs, exposure to a household contact was reported by 9% of cases and was associated with the highest risk of infection (aOR=7.8). Most infections were likely attributable to the more frequent exposure to infected patients (aOR=2.7) and coworkers (aOR=2.2). Wearing a N95 respirator during contacts with COVID-19 patients (aOR=0.7) and vaccination (aOR=0.2) were the measures associated with a risk reduction. Conclusion: In the context of the ever-changing SARS-CoV-2 virus with increasing transmissibility, measures to ensure HCWs’ protection, including vaccination and respiratory protection, and patients’ safety will need ongoing evaluation.