Speckle correction in polychromatic light with the self-coherent camera for the direct detection of exoplanets

TL;DR

This paper discusses the use of the Self-Coherent Camera (SCC) for speckle correction in polychromatic light to improve direct exoplanet detection, addressing challenges of spectral bandwidth and wavefront aberrations.

Contribution

It introduces a theoretical analysis and experimental testing of the SCC's performance in polychromatic light for enhanced speckle correction in exoplanet imaging.

Findings

Theoretical analysis of spectral bandwidth limitations.

Test bench results demonstrating SCC performance in polychromatic light.

Potential solutions for improving contrast over large spectral ranges.

Abstract

Direct detection is a very promising field in exoplanet science. It allows the detection of companions with large separation and allows their spectral analysis. A few planets have already been detected and are under spectral analysis. But the full spectral characterization of smaller and colder planets requires higher contrast levels over large spectral bandwidths. Coronagraphs can be used to reach these contrasts, but their efficiency is limited by wavefront aberrations. These deformations induce speckles, star lights leaks, in the focal plane after the coronagraph. The wavefront aberrations should be estimated directly in the science image to avoid usual limitations by differential aberrations in classical adaptive optics. In this context, we introduce the Self- Coherent Camera (SCC). The SCC uses the coherence of the star light to produce a spatial modulation of the speckles in the focal plane and estimate the associated electric complex field. Controlling the wavefront with a deformable mirror, high contrasts have already been reached in monochromatic light with this technique. The performance of the current version of the SCC is limited when widening the spectral bandwidth. We will present a theoretical analysis of these issues and their possible solution. Finally, we will present test bench performance in polychromatic light.