Calibration of the Instrumental Crosstalk for the Near-IR Imaging Spectropolarimeter at the NST

TL;DR

This paper discusses calibrating and compensating for instrumental crosstalk in the Near-IR Imaging Spectropolarimeter at the NST to improve the accuracy of solar polarization measurements.

Contribution

It presents a method to evaluate and correct for crosstalk caused by the telescope's relay optics without pre-mirror calibration optics.

Findings

Effective crosstalk calibration method developed.

Improved accuracy in Stokes parameter measurements.

Enhanced data processing pipeline for spectropolarimetry.

Abstract

The Near-IR Imaging Spectropolarimeter (NIRIS) is a polarimeter that is installed at the New Solar Telescope at Big Bear Solar Observatory. This instrument takes advantages of the highest spatial resolution and flux. The primary mirror is an on-axis type, so it was our interest to evaluate its contribution to the crosstalk among the Stokes parameters since we could not put our calibration optics before the mirror. We would like to present our efforts to compensate for the crosstalk among Stokes profiles caused by the relay optics from the telescope to the detector. The overall data processing pipeline is also introduced.