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Extreme Contrast Ratio Imaging of Sirius with a Charge-injection Device

Presentation #241.03D in the session “Optical Instrumentation and Performance”.

Published onJan 11, 2021
Extreme Contrast Ratio Imaging of Sirius with a Charge-injection Device

The intrinsic nature of astronomical objects, such as binary systems, exoplanets, and quasar host galaxies, introduces stringent requirements on observational instrumentation and techniques. We are yet to fully understand the processes governing star and galaxy formation and evolution. Additionally, there is an ongoing attempt to search for habitable worlds around other stars. To explore all features of such astronomical objects, we must perform observations with the maximum possible contrast ratios. The direct imaging of faint objects in the vicinity of bright sources imposes a critical constraint on the type of contrast observations achievable by ground- and space-based telescopes. Furthermore, the light from bright sources completely obscures the surrounding targets and saturates the conventional imaging instrumentation: charge-coupled devices and complementary metal-oxide-semiconductor detectors. Several point-spread suppression techniques (e.g., coronagraphy and nulling interferometry) are implemented to mitigate the signals from bright sources. However, their complex operational requirements make faint signal detection extremely difficult, expensive, and time-consuming.

The most feasible, practical, and cost-effective solution is to employ appropriate instrumentation that can carry out direct extreme contrast ratio (ECR) imaging. A new class of imaging detectors, charge-injection devices (CIDs), have the intrinsic ability to achieve ECRs owing to their unique readout architectures and inherent anti-blooming capabilities. CIDs have already demonstrated a direct contrast ratio of 1:20 million from sub-optimal ground-based astronomical observations. However, the atmospheric conditions introduced a practical limit on the contrast ratios that are otherwise achievable using CIDs. This research demonstrates the direct ECR imaging capabilities of the latest generation of commercially available CID, SpectraCAM XDR, at a world-class observing site with sub-arcsecond seeing conditions. Using the Sirius field observations, I will deliver a powerful yet cost-effective technique to achieve even greater contrast ratios. The results will potentially motivate us to consider CIDs as ECR imaging systems for future ground- and space-based observatories.

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