Ms. Katerina Papadaki Profile

Katerina Papadaki

at Institute of Astrophysics, Foundation for Research and Technology-Hella

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Author

Publications (3)

SPIE Journal Paper | 30 October 2024

Wide Area Linear Optical Polarimeter North instrument I: optical design, filter design, and calibration

John Andrew Kypriotakis, Siddharth Maharana, Ramya Anche, Chaitanya Rajarshi, Anamparambu Ramaprakash, Bhushan Joshi, Artem Basyrov, Dmitry Blinov, Tuhin Ghosh, Eirik Gjerløw, Sebastian Kiehlmann, Nikolaos Mandarakas, Georgia Panopoulou, Katerina Papadaki, Vasiliki Pavlidou, Timothy Pearson, Vincent Pelgrims, Stephen Potter, Anthony C. S. Readhead, Raphael Skalidis, Konstantinos Tassis

JATIS, Vol. 10, Issue 04, 044005, (October 2024) https://doi.org/10.1117/12.10.1117/1.JATIS.10.4.044005

KEYWORDS: Equipment, Tunable filters, Polarimetry, Optical filters, Polarization, Calibration, Design, Telescopes, Point spread functions, Stars

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SPIE Journal Paper | 6 September 2022

WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper II – polarimetric modeling and calibration

Siddharth Maharana, Ramya Anche, Anamparambu Ramaprakash, Bhushan Joshi, Artem Basyrov, Dmitry Blinov, Carolina Casadio, Kishan Deka, Hans Kristian Eriksen, Tuhin Ghosh, Eirik Gjerløw, John Kypriotakis, Sebastian Kiehlmann, Nikolaos Mandarakas, Georgia V. Panopoulou, Katerina Papadaki, Vasiliki Pavlidou, Timothy Pearson, Vincent Pelgrims, Stephen Potter, Anthony C. Readhead, Raphael Skalidis, Trygve Leithe Svalheim, Konstantinos Tassis, Ingunn Wehus

JATIS, Vol. 8, Issue 03, 038004, (September 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.3.038004

KEYWORDS: Polarimetry, Calibration, Polarization, Instrument modeling, Stars, Telescopes, Sensors, Zemax, Performance modeling, Systems modeling

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Proceedings Article | 29 August 2022 Presentation + Paper

Stress-induced birefringence in the lenses of Wide-Area Linear Optical Polarimeter-South

Ramya M. Anche, Siddharth Maharana, A. N. Ramaprakash, Pravin Khodade, Deepa Modi, Chaitanya Rajarshi, John A. Kypriotakis, Dmitry Blinov, Hans Kristian Eriksen, Tuhin Ghosh, Georgia V. Panopoulou, Vincent Pelgrims, Raphael Skalidis, Timothy J. Pearson, Eirik Gjerløw, Nikolaos Mandarakas, Vasiliki Pavlidou, Stephen B. Potter, Anthony C. S. Readhead, Konstantinos Tassis, Artem Basyrov, Katerina Papadaki, Trygve Leithe Svalheim, Ingunn K. Wehus

Proceedings Volume 12188, 121882C (2022) https://doi.org/10.1117/12.2629515

KEYWORDS: Birefringence, Polarization, Polarimetry, Telescopes, Finite element methods

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Two unique wide-field and high-accuracy polarimeters named WALOP (Wide-Area Linear Optical Polarimeter)- North and WALOP-South are currently under development at the Inter-University Center for Astronomy and Astrophysics (IUCAA), India, to create a large area optical polarization map of the sky for the upcoming PASIPHAE sky survey. These instruments are designed to achieve a linear polarimetric measurement accuracy of 0.1% across a field of view (FoV) of 30×30 arcminutes. The WALOP-South instrument will be installed first on a 1 m telescope at the Sutherland Observatory, where the temperatures during the night can vary between 10 to -5°C. These temperature variations and the instrument’s pointing to various non-zenithal positions in the sky can introduce stress birefringence in the lenses, leading to time-varying instrumental polarization. This work estimates stress-induced birefringence due to thermal, and gravity stresses on WALOP-South lenses. Using the optomechanical model of the WALOP-South, we carried out Finite Element Analysis (FEA) simulations in SolidWorks software to estimate the stresses for various scenarios of temperature, telescope pointing airmass, and lens mount material (aluminum and titanium). Further, we use the stress tensor analysis to estimate the principal stresses and their directions and consequent birefringence and retardance introduced in the lenses. The stressinduced birefringence will change the optical path length for orthogonal polarization states of the beam passing through the lenses and introduce phase retardation. Overall, with the lens mount design of the instrument, we find that the retardation and consequent instrumental polarization will be within the instrumental accuracy requirements. Additionally, the stress birefringence is found to be higher for aluminum compared to titanium mounts. We further incorporated this retardance in the instrument Mueller matrix estimation to understand its effects on the polarization measurements.

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