ABSTRACT
The inactivation or airborne pathogens inside closed spaces is a critical issue that raised overwhelmingly during the current SARS-CoV 2 pandemic. Among the different technologies to achieve air sanification, the ultraviolet germicidal irradiation is a trending technique, also due to the fast development of more and more effective ultra-violet LED sources, that are expected to replace the mercury vapor lamps in the next few years. The positioning of LEDs inside cavities with highly reflective surfaces permits an enhancement of the internal irradiance and the development of compact devices. Optical simulations, by means of ray tracing, are fundamental, since an accurate irradiance estimation in presence of multiple internal reflections, scattering, light leaks outside the cav-ity and the sources angular emission distribution is not possible with only analytical calculations. Ray tracing permits to model the spatial irradiance inside the cavity by varying the components parameters to maximize the inactivation rate as a function of the air flow field. We discuss, on the basis of the experience on several related projects, the advantages of using the numerical approach to simulate these devices, focusing the attention onto the critical parameters which must be controlled to retrieve a reliable estimation of the system performance. © COPYRIGHT SPIE. Downloading of the is permitted for personal use only.
ABSTRACT
SHARK-NIR is a high contrast camera for the LBT, working in Y, J and H bands. It has been conceived and designed to fully exploit the high Strehl adaptive optics correction delivered by the FLAO module, which is being upgraded to SOUL, and will implement different coronagraphic techniques, with contrast as high as 10-6 up to 65 mas from the star. To maximize the achievable contrast, SHARK-NIR has a couple of peculiar features, namely a fast internal TT loop to minimize the residual jitter and a local NCPA correction, performed through a DM inside the instrument itself. Other than high-contrast imaging, SHARK-NIR also has spectroscopic capabilities, with low and medium resolution, and its relatively wide Field of View (18 x 18 arcsec) makes it accessible to other scientific targets, such as galactic jets and disks, as well as extra-galactic cases. Sharing the focal station with another instrument at LBT (LBTI), the design has been kept very compact. This has been achieved through the use of 4 Off-Axis Parabolic mirrors (OAPs) and three flat folding mirrors able to provide two pupil planes and two focal planes required by the coronagraphic techniques implemented. A mixed optical-mechanical alignment procedure has been identified and extensively simulated using ray-tracing software, demonstrating that the proposed technique converges to the required performance. We report here about the SHARK-NIR lesson learned and status in the frame of the Assembly, Integration &Verification phase (AIV), delayed due to the covid 19 emergency, which is going to finish in first half of 2021 and bringing in this way the first photons to the instrument by the end of 2021. © 2020 SPIE