Maturing electron multiplying charge coupled device photon-counting with variable multiplication gain imaging for a...

Area of Science:

• Astronomy and Astrophysics
• Instrumentation and Technology

Background:

• High-contrast astronomical imaging aims to detect faint objects near bright stars.
• Electron multiplying charge coupled devices (EMCCDs) are used in photon-counting instruments for this purpose.
• Charge blooming and starlight saturation degrade the performance of EMCCD-based coronagraphs.

Purpose of the Study:

• To introduce and address the challenges of charge blooming and starlight saturation in EMCCD-based coronagraphy.
• To propose a novel clocking scheme for EMCCDs to mitigate these issues.
• To discuss the design of a new controller for advanced EMCCD coronagraphic instruments.

Main Methods:

• Experiments were conducted using a commercial EMCCD camera in a visible nulling coronagraph at Goddard Space Flight Center.
• The concepts of charge blooming and starlight saturation were analyzed in the context of high-contrast imaging.
• A new variable multiplication gain clocking scheme for EMCCDs was developed and proposed.

Main Results:

• Charge blooming and starlight saturation were identified as significant limitations for photon-counting instruments without physical starlight blocking.
• The proposed variable multiplication gain clocking scheme demonstrates potential for suppressing these adverse phenomena.
• Design considerations for a new controller enabling simultaneous photon-counting, digitization, and variable gain clocking were discussed.

Conclusions:

• Variable multiplication gain clocking offers a promising solution for improving EMCCD performance in high-contrast astronomical imaging.
• A new controller design is crucial for realizing the full potential of EMCCDs in advanced coronagraphic applications.
• This work paves the way for simultaneous exoplanet direct imaging and wavefront control in coronagraphs.