Daniel K. Inouye Solar Telescope (DKIST) is designed to deliver accurate spectro-polarimetric solar data across a wide wavelength range, covering a large field of view simultaneously using multiple facility instruments for solar disk, limb, and coronal observations. We show successful design and implementation of National Solar Observatory Coude Laboratory Spectropolarimeter, a custom metrology tool for efficient continuous broadband polarization calibration of the telescope mirrors through a coude laboratory focus. We compare multiple fitting techniques for the 10 to >140 variable DKIST system polarization models. We compare results with the first DKIST solar calibration observations and find small thermally forced retardance changes of +/- 0.2 deg and +/- 0.5 deg for two separate SiO2 retarders. Modulation matrices derived are stable to < +/- 0.01 per element during the first on-Sun calibration tests. We achieve good fit agreement to our metrology-based model over a 390- to 1600-nm bandpass. The solutions are robust and efficient using only 10 input Stokes vectors from elliptical calibration retarders. We developed a custom polarizer assembly used with metrology tools to orient the DKIST polarization coordinates to better than 0.1-deg clocking angle. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Stuart J. Mumford∗1, 2, 3, Nabil Freij4, Steven Christe5, Jack Ireland5, Florian Mayer6, V. Keith Hughitt7, Albert Y. Shih5, Daniel F. Ryan8, 5, Simon Liedtke6, David Pérez-Suárez9, Pritish Chakraborty10, Vishnunarayan K I.6, Andrew Inglis11, Punyaslok Pattnaik12, Brigitta Sipőcz13, Rishabh Sharma6, Andrew Leonard3, David Stansby14, Russell Hewett15, Alex Hamilton6, Laura Hayes5, Asish Panda6, Matt Earnshaw6, Nitin Choudhary16, Ankit Kumar6, Prateek Chanda17, Md Akramul Haque18, Michael S Kirk11, Michael Mueller6, Sudarshan Konge6, Rajul Srivastava6, Yash Jain19, Samuel Bennett6, Ankit Baruah6, Will Barnes20, Michael Charlton6, Shane Maloney21, Nicky Chorley22, Himanshu6, Sanskar Modi6, James Paul Mason6, Naman96396, Jose Ivan Campos Rozo23, Larry Manley6, Agneet Chatterjee24, John Evans6, Michael Malocha6, Monica G. Bobra25, Sourav Ghosh24, Airmansmith976, Dominik Stańczak26, Ruben De Visscher6, Shresth Verma27, Ankit Agrawal6, Dumindu Buddhika6, Swapnil Sharma6, Jongyeob Park28, Matt Bates6, Dhruv Goel6, Garrison Taylor29, Goran Cetusic6, Jacob6, Mateo Inchaurrandieta6, Sally Dacie30, Sanjeev Dubey6, Deepankar Sharma6, Erik M. Bray6, Jai Ram Rideout31, Serge Zahniy5, Tomas Meszaros6, Abhigyan Bose6, André Chicrala32, Ankit6, Chloé Guennou6, Daniel D’Avella6, Daniel Williams33, Jordan Ballew6, Nick Murphy34, Priyank Lodha6, Thomas Robitaille6, Yash Krishan6, Andrew Hill6, Arthur Eigenbrot35, Benjamin Mampaey36, Bernhard M. Wiedemann6, Carlos Molina6, Duygu Keşkek6, Ishtyaq Habib6, Joseph Letts6, Juanjo Bazán37, Quinn Arbolante38, Reid Gomillion6, Yash Kothari6, Yash Sharma6, Abigail L. Stevens39, 40, Adrian Price-Whelan41, Ambar Mehrotra6, Arseniy Kustov6, Brandon Stone6, Trung Kien Dang42, Emmanuel Arias6, Fionnlagh Mackenzie Dover1, Freek Verstringe36, Gulshan Kumar43, Harsh Mathur44, Igor Babuschkin6, Jaylen Wimbish6, Juan Camilo Buitrago-Casas6, Kalpesh Krishna45, Kaustubh Hiware46, Manas Mangaonkar6, Matthew Mendero6, Mickaël Schoentgen6, Norbert G Gyenge47, Ole Streicher48, Rajasekhar Reddy Mekala6, Rishabh Mishra6, Shashank Srikanth43, Sarthak Jain6, Tannmay Yadav49, Tessa D. Wilkinson6, Tiago M. D. Pereira50, 51, Yudhik Agrawal12, jamescalixto6, yasintoda6, and Sophie A. Murray52