Open AccessDesign and analysis of a five-mirror derotator with minimal instrumental polarization in astronomical telescopes
Author(s) -
Jing Hou,
Ming Liang,
Dongguang Wang,
Yuanyong Deng
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.019356
Subject(s) - optics , polarimetry , physics , polarization (electrochemistry) , mueller calculus , scattering , chemistry
It is well known that derotator is commonly used to compensate for image rotation in astronomical telescopes. The classical derotator, consisting of three mirrors, is named K-mirror. The main disadvantage of the K-mirror is that it has high instrumental polarization, causing a larger polarization measurement error in polarimetry. In the paper, we proposed a new design of the derotator based on the Mueller matrix transformation theory of mirrors in polarized light. The new designed derotator contains five mirrors and is called five-mirror derotator. It has a very small instrumental polarization, overcoming the shortcomings of the classical K-mirror. A novel method is applied to compensate for the beam shift induced by the thickness of the reflector. From the result of numerical polarization analysis, it is showed that the five-mirror derotator has a significant advantage for the telescopes with a small field of view, especially in polarimetry at longer wavelengths.