Concept of an achromatic stellar coronagraph and its application for detecting extrasolar planets by Bhavesh Jaiswal. on Tuesday 29 November

Imaging the planets that orbit around other stars requires blocking the host

star which is usually 8-10 orders of magnitude brighter than the planets. This

is achieved with the help of a stellar coronagraph. In the current work, a

concept of a new type of stellar coronagraph is introduced where the star light

is blocked by a linear polarizer in the collimated beam. It is based on

differential rotation between the linear polarization state of planet light and

that of star light. This is achieved with the help of a set of thick

birefringent crystals in the collimated beam of a telescope where the planet

light is made to travel extra optical path length compared to star light. By

adjusting the orientation and thickness of the crystal, the optical path length

can be made to cause a phase difference of {\pi}, just enough to rotate the

initial plane of polarization by 90{\deg} for planet-light without affecting

the star light. Theoretical calculations involving the phase difference due to

birefringent crystals are presented here along with the basic configuration and

design. It is shown that the design blocks the star light identically at all

wavelengths. Application of this concept for detecting Earth-like extrasolar

planet is discussed using a one-meter class telescope.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.14624v1