Mr. Pravinkumar A. Chordia Profile

Pravinkumar A. Chordia

Scientific Officer at Inter-Univ Ctr for Astronomy and Astrophysics

SPIE Involvement:

Author

Publications (15)

Proceedings Article | 18 July 2024 Poster + Paper

Poster + Paper

Systems design, assembly, integration, and lab testing of WALOP-South Polarimeter

Siddharth Maharana, A. Ramaprakash, Chaitanya Rajarshi, Pravin Khodade, Bhushan Joshi, Pravin Chordia, Abhay Kohok, Ramya Anche, Deepa Modi, John Kypriotakis, Amit Deokar, Aditya Kinjawadekar, Stephen Potter, Dmitry Blinov, Hans Kristian Eriksen, Myrto Falalaki, Hitesh Gajjar, Tuhin Ghosh, Eirik Gjerløw, Sebastian Kiehlmann, Ioannis Liodakis, Nikolaos Mandarakas, Georgia Panopoulou, Vasiliki Pavlidou, Timothy Pearson, Vincent Pelgrims, Anthony C. Readhead, Raphael Skalidis, Konstantinos Tassis, Namita Uppal, Ingunn Wehus

Proceedings Volume 13096, 130967P (2024) https://doi.org/10.1117/12.3016144

KEYWORDS: Equipment, Cameras, Polarimetry, Polarizers, Collimators, Telescopes, Cements, Polarization, Calibration, Optomechanical design, Optical design, Calcite

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Wide-Area Linear Optical Polarimeter (WALOP)-South is the first wide-field and survey-capacity polarimeter in the optical wavelengths. On schedule for commissioning in 2024, it will be mounted on the 1 m SAAO telescope in Sutherland Observatory, South Africa to undertake the PASIPHAE sky survey. PASIPHAE program will create the first polarimetric sky map in the optical wavelengths, spanning more than 2000 square degrees of the southern Galactic region. In a single exposure, WALOP-South’s innovative design will enable it to measure the linear polarization (Stokes parameters q and u) of all sources in a field of view (FoV) of 35 × 35 arc-minutes-squared in the SDSS-r broadband and narrowband filters between 500-750 nm with 0.1 % polarization accuracy. The unique goals of the instrument place very stringent systems engineering goals, including on the performance of the optical, polarimetric, optomechanical, and electronic subsystems. In particular, the major technical hurdles for the project included the development of: (a) an optical design to achieve imaging quality PSFs across the FoV, (b) an optomechanical design to obtain high accuracy optical alignment in conjugation with minimal instrument flexure and stress birefringence on optics (which can lead to variable instrumental polarization), and (c) an on-sky calibration routine to remove the strong polarimetric cross-talk induced instrumental polarization to obtain 0.1% across the FoV. All the subsystems have been designed carefully to meet the overall instrument performance goals. As of May 2024, all the instrument optical and mechanical subsystems have been assembled and are currently getting tested and integrated. The complete testing and characterization of the instrument in the lab is expected to be completed by August 2024. While the instrument was initially scheduled for commissioning in 2022, it got delayed due to various technical challenges; WALOP-South is now on schedule for commissioning in second half of 2024. In this paper, we will present (a) the design and development of the entire instrument and its major subsystems, focusing the instrument’s opto-mechanical design which has not been reported before, and (b) assembly and integration of the instrument in the lab and early results from lab characterization of the instrument’s optical performance.

Proceedings Article | 13 December 2020 Poster + Presentation + Paper

Poster + Presentation + Paper

WALOP-South: A wide-field one-shot linear optical polarimeter for PASIPHAE survey

Siddharth Maharana, John Kypriotakis, A. Ramaprakash, Pravin Khodade, Chaitanya Rajarshi, Bhushan Joshi, Pravin Chordia, Ramya Anche, Shrish Mishra, Dmitry Blinov, Hans Kristian Eriksen, Tuhin Ghosh, Eirik Gjerløw, Nikolaos Mandarakas, Georgia Panopoulou, Vasiliki Pavlidou, Timothy Pearson, Vincent Pelgrims, Stephen Potter, Anthony C. Readhead, Raphail Skalidis, Konstantinos Tassis, Ingunn Wehus

Proceedings Volume 11447, 114475E (2020) https://doi.org/10.1117/12.2554396

KEYWORDS: Polarimetry, Polarization, Telescopes, Stars, Astronomy, Optical filters, Photometry, Prisms, Vignetting, Optomechanical design

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SPIE Journal Paper | 25 July 2019 Open Access

Open Access

Design and development of an adaptive optics system in visible and near-infrared for Inter-University Centre for Astronomy and Astrophysics 2-meter telescope

Jyotirmay Paul, Hillol Kanti Das, Anamparambu Ramaprakash, Mahesh Burse, Pravinkumar Chordia, Kalpesh Chillal, Gaurav Datir, Bhushan Joshi, Pravin Khodade, Abhay Kohok, Vilas Mestry, Sujit Punnadi, Chaitanya Rajarshi, Chikku Shekhar

JATIS, Vol. 5, Issue 03, 039002, (July 2019) https://doi.org/10.1117/12.10.1117/1.JATIS.5.3.039002

KEYWORDS: Adaptive optics, Telescopes, Prisms, Cameras, Projection systems, Ultraviolet radiation, Mirrors, Infrared cameras, Zemax, Atmospheric modeling

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Proceedings Article | 11 July 2018 Paper

Paper

Design and development of IR camera

Jyotirmay Paul, A. Ramaprakash, Hillol Das, Mahesh Burse, Pravin Chordia, Pravin Khodade, Abhay Kohok, Vilas Mestry , Deepa Modi , Sujit Punnadi, Chaitanya Rajarshi

Proceedings Volume 10703, 1070368 (2018) https://doi.org/10.1117/12.2311457

KEYWORDS: Infrared cameras, Cameras, Sensors, Optical filters, Adaptive optics, Infrared sensors, Telescopes, Infrared telescopes, Infrared radiation

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SPIE Journal Paper | 11 July 2018

Noise characterization of IUCAA digital sampling array controller

Sabyasachi Chattopadhyay, A. N. Ramaprakash, Bhushan Joshi, Pravinkumar Chordia, Mahesh Burse, Kalpesh Chillal, Sakya Sinha, Sujit Punnadi, Ketan Rikame, Sungwook Hong, Dhruv Paranjpye, Haeun Chung, Changbom Park, Amitesh Omar

JATIS, Vol. 4, Issue 03, 036002, (July 2018) https://doi.org/10.1117/12.10.1117/1.JATIS.4.3.036002

KEYWORDS: Interference (communication), Charge-coupled devices, Electrons, Analog electronics, Clocks, Amplifiers, Power supplies, Sensors, Field programmable gate arrays, Statistical modeling

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The IUCAA digital sampling array controller (IDSAC) is a flexible and generic yet powerful CCD controller that can handle a wide range of scientific detectors. Based on an easily scalable modular backplane architecture consisting of single board controllers (SBC), IDSAC can control large detector arrays and mosaics. Each of the SBCs offers the full functionality required to control a CCD independently. The SBCs can be cold swapped without the need to reconfigure them. IDSAC is also available in a backplane-less architecture. Each SBC can handle data from up to four video channels with or without dummy outputs at speeds up to 500-kilo pixels per second (kPPS) per channel with a resolution of 16 bits. Communication with a Linux-based host computer is through a USB3.0 interface, with the option of using copper or optical fibers. A field programmable gate array (FPGA) is used as the master controller in each SBC, which allows great flexibility in optimizing performance by adjusting gain, timing signals, bias levels, etc., using user-editable configuration files without altering the circuit topology. Elimination of thermal kTC noise is achieved via digital correlated double sampling (DCDS). The number of digital samples per pixel (for both reset and signal levels) is user configurable. We present the results of noise performance characterization of IDSAC through simulation, theoretical modeling, and actual measurements. The contribution of different types of noise sources is modeled using a tool to predict noise of a generic DCDS signal chain analytically. The analytical model predicts the net input referenced noise of the signal chain to be 5 electrons for 200-k pixels/s per channel readout rate with three samples per pixel. Using a cryogenic test setup in the lab, the noise is measured to be 5.4 e (24.3 μV), for the same readout configuration. With a better-optimized configuration of 500-kPPS readout rate, the measured noise is down to 3.8 electrons RMS (17 μV), with three samples per interval.

Proceedings Article | 9 July 2018 Paper

Paper

DOTIFS: fore-optics and calibration unit design

Haeun Chung, A. Ramaprakash, Pravin Khodade, Chaitanya Rajarshi, Sabyasachi Chattopadhyay, Pravin Chordia, Amitesh Omar, Changbom Park

Proceedings Volume 10702, 107027U (2018) https://doi.org/10.1117/12.2312394

KEYWORDS: Calibration, Telescopes, Lamps, Mirrors, Integrating spheres, Spectrographs, Lenses, Light, Optical instrument design, Optomechanical design

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Proceedings Article | 8 July 2018 Paper

Paper

DOTIFS: spectrograph optical and opto-mechanical design

Haeun Chung, A. N. Ramaprakash, Pravin Khodade, Deepa Modi, Chaitanya Rajarshi, Sabyasachi Chattopadhyay, Pravin Chordia, Vishal Joshi, Sungwook Hong, Amitesh Omar, Swara Ravindranath, Yong-Sun Park, Changbom Park

Proceedings Volume 10702, 107027A (2018) https://doi.org/10.1117/12.2311594

KEYWORDS: Spectrographs, Cameras, Charge-coupled devices, Optical design, Collimators, Optical filters, Spectral resolution, Tolerancing, Optomechanical design, Optical fibers, Thermal analysis

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Proceedings Article | 6 July 2018 Paper

Paper

Design and results for the SAAO wide-field nasmyth camera

Pieter Swanevelder, Dave Carter, James O'Connor, Hannah Worters, Willie Koorts, Briehan Lombaard, Egan Loubser, Keegan Titus, Carel van Gend, Michael Rust, Craig Sass, Hitesh Gajjar, Amanda Sickafoose, A. N. Ramaprakash, Pravin Chordia, Mahesh Burse, Sujit Punnadi, Bhushan Joshi, Sakya Sinha

Proceedings Volume 10702, 107022K (2018) https://doi.org/10.1117/12.2312540

KEYWORDS: Camera shutters, Charge-coupled devices, Cameras, Telescopes, Astronomy

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Proceedings Article | 19 August 2016 Paper

Paper

First results and future plans for the Canarias Infrared Camera Experiment (CIRCE) for the Gran Telescopio Canarias

Alan Garner, Stephen Eikenberry, Miguel Charcos, Yigit Dallilar, Michelle Edwards, Nestor Lasso-Cabrera, Richard Stelter, Antonio Marin-Franch, S. Nicholas Raines, Kendall Ackley, John Bennett, Javier Cenarro , Brian Chinn, Veronica Donoso, Raymond Frommeyer, Kevin Hanna, Michael Herlevich, Jeff Julian, Paola Miller, Scott Mullin, Charles Murphey, Christopher Packham, Frank Varosi, Claudia Vega, Craig Warner, Anamparambu Ramaprakash, Mahesh Burse, Sujit Punnadi, Pravinkumar Chordia, Andreas Gerarts, Héctor de Paz Martín, María Martín Calero, Riccardo Scarpa, Sergio Fernandez Acosta, William Miguel Hernández Sánchez, Benjamin Siegel, Francisco Francisco Pérez, Himar Viera Martín, José Rodríguez Losada, Agustín Nuñez, Álvaro Tejero, Carlos E. Martín González, César Cabrera Rodríguez, Jordi Molgó Sendra, J. Esteban Rodriguez, J. Israel Fernádez Cáceres, Luis A. Rodríguez García, Manuel Huertas Lopez, Raul Dominguez, Tim Gaggstatter, Antonio Cabrera-Lavers, Stefan Geier, Peter Pessev, Ata Sarajedini, A. J. Castro-Tirado

Proceedings Volume 9908, 99084Q (2016) https://doi.org/10.1117/12.2232672

KEYWORDS: Infrared cameras, Polarimetry, Astronomy, X-rays, Stars, Spectroscopy, Spectroscopes, Sensors, Galactic astronomy, Binary data

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Proceedings Article | 27 July 2016 Paper

Paper

ISDEC-2 and ISDEC-3 controllers for HAWAII detectors

Mahesh Burse, A. Ramaprakash, Pravinkumar Chordia, Sujit Punnadi, Kalpesh Chillal, Vilas Mestri, Rupali Bharti, Sakya Sinha, Abhay Kohok

Proceedings Volume 9915, 991526 (2016) https://doi.org/10.1117/12.2232510

KEYWORDS: Sensors, Electronics, Astronomy, Observatories, Telescopes, Field programmable gate arrays, Interfaces, Clocks, Control systems, Analog electronics

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Proceedings Article | 27 July 2016 Paper

Paper

IDSAC-IUCAA digital sampler array controller

Sabyasachi Chattopadhyay, Pravin Chordia, A. Ramaprakash, Mahesh Burse, Bhushan Joshi, Kalpesh Chillal

Proceedings Volume 9915, 991524 (2016) https://doi.org/10.1117/12.2232477

KEYWORDS: Charge-coupled devices, Video processing, Cadmium sulfide, Video, Analog electronics, Interference (communication), Clocks, Sensors, Power supplies, Signal to noise ratio

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In order to run the large format detector arrays and mosaics that are required by most astronomical instruments, readout electronic controllers are required which can process multiple CCD outputs simultaneously at high speeds and low noise levels. These CCD controllers need to be modular and configurable, should be able to run multiple detector types to cater to a wide variety of requirements. IUCAA Digital Sampler Array Controller (IDSAC), is a generic CCD Controller based on a fully scalable architecture which is adequately flexible and powerful enough to control a wide variety of detectors used in ground based astronomy. The controller has a modular backplane architecture that consists of Single Board Controller Cards (SBCs) and can control up to 5 CCDs (mosaic or independent). Each Single Board Controller (SBC) has all the resources to a run Single large format CCD having up to four outputs. All SBCs are identical and are easily interchangeable without needing any reconfiguration. A four channel video processor on each SBC can process up to four output CCDs with or without dummy outputs at 0.5 Megapixels/Sec/Channel with 16 bit resolution. Each SBC has a USB 2.0 interface which can be connected to a host computer via optional USB to Fibre converters. The SBC uses a reconfigurable hardware (FPGA) as a Master Controller. IDSAC offers Digital Correlated Double Sampling (DCDS) to eliminate thermal kTC noise. CDS performed in Digital domain (DCDS) has several advantages over its analog counterpart, such as - less electronics, faster readout and easier post processing. It is also flexible with sampling rate and pixel throughput while maintaining the core circuit topology intact. Noise characterization of the IDSAC CDS signal chain has been performed by analytical modelling and practical measurements. Various types of noise such as white, pink, power supply, bias etc. has been considered while creating an analytical noise model tool to predict noise of a controller system like IDSAC. Several tests are performed to measure the actual noise of IDSAC. The theoretical calculation matches very well with practical measurements within 10% accuracy.

Proceedings Article | 27 July 2016 Paper

Paper

Evaluating noise performance of the IUCAA sidecar drive electronics controller (ISDEC) based system for TMT on-instrument wavefront sensing (OIWFS) application

Mahesh Burse, Sabyasachi Chattopadhyay, A. Ramaprakash, Sakya Sinha, Swapnil Prabhudesai, Sujit Punnadi, Pravin Chordia, Abhay Kohok

Proceedings Volume 9915, 991520 (2016) https://doi.org/10.1117/12.2232265

KEYWORDS: Sensors, Wavefront sensors, Control systems, Analog electronics, Multiplexers, Stars, Field programmable gate arrays, Power supplies, Electrons, Interfaces

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Proceedings Article | 18 July 2016 Paper

Paper

The Solar Ultraviolet Imaging Telescope onboard Aditya-L1

Avyarthana Ghosh, Subhamoy Chatterjee, Aafaque Khan, Durgesh Tripathi, A. Ramaprakash, Dipankar Banerjee, Pravin Chordia, Achim Gandorfer, Natalie Krivova, Dibyendu Nandy, Chaitanya Rajarshi, Sami Solanki, S. Sriram

Proceedings Volume 9905, 990503 (2016) https://doi.org/10.1117/12.2232266

KEYWORDS: Space operations, Ultraviolet radiation, Space telescopes, Telescopes, Space telescopes, Solar processes, Sensors, X-ray imaging, Plasma, Ions, Magnetosphere

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Proceedings Article | 8 July 2014 Paper

Paper

Project status of the Robert Stobie spectrograph near infrared instrument (RSS-NIR) for SALT

Marsha Wolf, Mark Mulligan, Michael Smith, Douglas Adler, Curtis Bartosz, Matthew Bershady, David Buckley, Mahesh Burse, Pravin Chordia, J. Christopher Clemens, Harland Epps, Kristine Garot, Briana Indahl, Kurt Jaehnig, Ron Koch, William Mason, Gregory Mosby, Kenneth Nordsieck, Jeffrey Percival, Sujit Punnadi, Anamparambu Ramaprakash, J. Alan Schier, Andrew Sheinis, Stephen Smee, Donald Thielman, Mark Werner, Theodore Williams, Jeffrey Wong

Proceedings Volume 9147, 91470B (2014) https://doi.org/10.1117/12.2056736

KEYWORDS: Sensors, Cameras, Near infrared, Diffraction gratings, Beam splitters, Optical filters, Collimators, Received signal strength, Spectroscopes, Telescopes

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Proceedings Article | 20 July 2010 Paper

Paper

Controller and data acquisition system for SIDECAR ASIC driven HAWAII detectors

Anamparambu Ramaprakash, Mahesh Burse, Pravin Chordia, Kalpesh Chillal, Abhay Kohok, Vilas Mestry, Sujit Punnadi, Sakya Sinha

Proceedings Volume 7742, 77422I (2010) https://doi.org/10.1117/12.858455

KEYWORDS: Sensors, Data acquisition, Human-machine interfaces, Staring arrays, Field programmable gate arrays, Cryogenics, Astronomy, Electrons, Interfaces, Readout integrated circuits

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Showing 5 of 15 publications

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