Abstract

The Daniel K. Inouye Solar Telescope (DKIST) advances studies of solar magnetism through high-precision and accuracy in polarimetry at frontier spatial and temporal scales. A system model for polarization response in azimuth and altitude has been developed to calibrate DKIST instruments. The DKIS... Show moreThe Daniel K. Inouye Solar Telescope (DKIST) advances studies of solar magnetism through high-precision and accuracy in polarimetry at frontier spatial and temporal scales. A system model for polarization response in azimuth and altitude has been developed to calibrate DKIST instruments. The DKIST team has developed several new modeling and performance-estimation techniques coupled with thorough metrology. These efforts ensure that quality polarimetry is delivered to meet stringent accuracy requirements. A custom spectropolarimetric calibration system was designed, installed, and used to perform end-to-end calibration of the telescope using the beam within the Cryo-NIRSP instrument. Extensive optical and polarization characterization efforts allow for the reduction of systematic errors within a detailed system model that includes elliptical calibration retarders. Coating witness samples for every relevant optic in the system have been measured. Aperture-dependent variations in polarizer, retarder, and optic-coating performance have been measured and used to simulate both the polarization dependence on field angle and errors within the optical-system model. Multiple observations on-Sun and with a calibration lamp agree well with each other and with the system model. Upcoming multi-instrument observations are expected to be well calibrated with detailed understanding of major error limitations. Show less