Speaker
Description
The Nancy Grace Roman Space Telescope is a 2.4 m flagship astrophysics mission currently planned for launch in 2026. The secondary Coronagraph Instrument (CGI) shall demonstrate key technologies required for high contrast imaging and spectroscopy of planetary systems, including adaptive optics, high-speed (1 kHz) wavefront sensing and photon counting detectors in the form of Electron Multiplying CCDs (EMCCDs). The two camera systems, ExCam and LoCam, are integral to each of these demonstrations and operate in contrasting optical environments with almost identical designs. ExCam is the exoplanetary systems camera responsible for planetary system imaging and characterization. It is designed to operate at frame rates of order 1 FPS at flux levels ranging from 10^4 to 10^-3 counts/pix/s. An in-built electron multiplication mechanism on the detector provides single photon sensitivity during CGI science observations. LoCam is responsible for the high speed wavefront sensing and pointing control. It operates at 1000 FPS with targets in the range 10^3 to 10^7 counts/pix/s. Here, the EMCCD is used to provide low system noise while maintaining a high frame rate. Together, each camera is responsible for both high and low order wavefront control that shall enable contrast of up to 10^-8 for science targets; up to a x100 improvement on the current state of the art. Here, we describe the assembly, commissioning and calibration of ExCam and LoCam prior to integration on the CGI optical bench. Electro-optical performance characterization is discussed alongside the development of software readout sequences specific to each camera. We conclude with lessons learned from this work for future generations of such camera systems.
Keywords for your contribution subject matter (this will assist SOC in accurately characterizing your contribution)
EMCCDs, CCDs, photon counting, Roman CGI
| contribution subject matter | CCD sensors |
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