Coronagraph Experiment on Dark-hole Control by Speckle Area Nulling Method

TL;DR

This paper introduces the speckle area nulling (SAN) method, a new algorithm for controlling speckle noise in high-contrast imaging systems, validated through a monochromatic light experiment.

Contribution

The SAN method is a novel, model-independent algorithm capable of quickly controlling speckle electric fields over wide areas in high-contrast imaging.

Findings

Reduced speckle intensity by 4.4e-2 in experiments

Demonstrated robustness and wide-area control capability

Validated with monochromatic light in a laboratory setting

Abstract

In high-contrast imaging optical systems for direct observation of planets outside our solar system, adaptive optics with an accuracy of lambda/10,000 root mean square is required to reduce the speckle noise down to 1e-10 level in addition to the nulling coronagraph which eliminate the diffracted light. We developed the speckle area nulling (SAN) method as a new dark-hole control algorithm which is capable of controlling speckle electric field in a wide area quickly, in spite of an extension of speckle nulling, and is robust not relying upon an optical model. We conducted a validation experiment for the SAN method with a monochromatic light and succeeded in reducing the intensity of areal speckles by 4.4e-2.