Browsing by Author "Adler, Alexandre E."

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    Simons Observatory: characterizing the Large Aperture Telescope Receiver with radio holography
    (2022) Chesmore, Grace E.; Harrington, Kathleen; Sierra, Carlos E.; Gallardo, Patricio A.; Sutariya, Shreya; Alford, Tommy; Adler, Alexandre E.; Bhandarkar, Tanay; Coppi, Gabriele; Dachlythra, Nadia; Golec, Joseph; Gudmundsson, Jon; Haridas, Saianeesh K.; Johnson, Bradley R.; Kofman, Anna M.; Iuliano, Jeffrey; Mcmahon, Jeff; Niemack, Michael D.; Orlowski-Scherer, John; Sarmiento, Karen Perez; Puddu, Roberto; Silva-Feaver, Max; Simon, Sara M.; Robe, Julia; Wollack, Edward J.; Xu, Zhilei
    We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments. (c) 2022 Optica Publishing Group
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    The Simons Observatory: Beam Characterization for the Small Aperture Telescopes
    (2024) Dachlythra, Nadia; Duivenvoorden, Adriaan J.; Gudmundsson, Jon E.; Hasselfield, Matthew; Coppi, Gabriele; Adler, Alexandre E.; Alonso, David; Azzoni, Susanna; Chesmore, Grace E.; Fabbian, Giulio; Ganga, Ken; Gerras, Remington G.; Jaffe, Andrew H.; Johnson, Bradley R.; Keating, Brian; Keskitalo, Reijo; Kisner, Theodore S.; Krachmalnicoff, Nicoletta; Lungu, Marius; Matsuda, Frederick; Naess, Sigurd; Page, Lyman; Puddu, Roberto; Puglisi, Giuseppe; Simon, Sara M.; Teply, Grant; Tsan, Tran; Wollack, Edward J.; Wolz, Kevin; Xu, Zhilei
    We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on a mapmaker that estimates and subtracts correlated atmospheric noise and a beam fitting code designed to compensate for the bias caused by the mapmaker. We test our reconstruction performance for four different frequency bands against various algorithmic parameters, atmospheric conditions, and input beams. We additionally show the reconstruction quality as a function of the number of available observations and investigate how different calibration strategies affect the beam uncertainty. For all of the cases considered, we find good agreement between the fitted results and the input beam model within an similar to 1.5% error for a multipole range l = 30-700 and an similar to 0.5% error for a multipole range l = 50-200. We conclude by using a harmonic-domain component separation algorithm to verify that the beam reconstruction errors and biases observed in our analysis do not significantly bias the Simons Observatory r-measurement
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    The Simons Observatory: modeling optical systematics in the Large Aperture Telescope
    (2021) Gudmundsson, Jon E.; Gallardo, Patricio A.; Puddu, Roberto; Dicker, Simon R.; Adler, Alexandre E.; Ali, Aamir M.; Bazarko, Andrew; Chesmore, Grace E.; Coppi, Gabriele; Cothard, Nicholas F.; Dachlythra, Nadia; Devlin, Mark; Dunner, Rolando; Fabbian, Giulio; Galitzki, Nicholas; Golec, Joseph E.; Ho, Shuay-Pwu Patty; Hargrave, Peter C.; Kofman, Anna M.; Lee, Adrian T.; Limon, Michele; Matsuda, Frederick T.; Mauskopf, Philip D.; Moodley, Kavilan; Nati, Federico; Niemack, Michael D.; Orlowski-Scherer, John; Page, Lyman A.; Partridge, Bruce; Puglisi, Giuseppe; Reichardt, Christian L.; Sierra, Carlos E.; Simon, Sara M.; Teply, Grant P.; Tucker, Carole; Wollack, Edward J.; Xu, Zhilei; Zhu, Ningfeng
    We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope, allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics that are now being built. We describe nonsequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tracing simulations of the telescope structure that allow us to determine geometries that minimize detector loading and mitigate spurious near-field effects that have not been resolved by the internal baffling. We also describe physical optics simulations, performed over a range of frequencies and field locations, that produce estimates of monochromatic far-field beam patterns, which in turn are used to gauge general optical performance. Finally, we describe simulations that shed light on beam sidelobes from panel gap diffraction. (C) 2021 Optical Society of America