Development and Validation of an EMCCD Simulator in MATLAB

A current development effort at Virginia Tech is the development of a CubeSat form-factor instrument for measuring nitric oxide in the mesosphere and lower thermosphere in the polar night. This will enable the investigation of important heliophysics science questions regarding the coupling of the Sun-Earth system through energetic particle precipitation into the auroral regions, a primary mechanism for nitric oxide generation in these regions. This will be accomplished through implementing the stellar occultation technique to measure star light at 215 nm, corresponding to the γ(1,0) absorption feature of nitric oxide. Measurement of the attenuation compared to an exoatmospheric measurement enables the retrieval of the nitric oxide altitude profile as the instrument line-of-sight traverses the atmosphere during occultations. The high signal-to-noise ratio required to measure the nitric oxide density during each occultation while meeting the constraints of the CubeSat form factor will be achieved in part through the use of an electron multiplying charge coupled device (EMCCD) to enable photon counting during observations, virtually eliminating the impact of read noise. EMCCDs are a novel component for space missions and are baselined for the Roman Space Telescope coronagraph instrument.

As part of efforts to develop instrument simulation capabilities, a MATLAB EMCCD model has been created. The objective of this model is to be able to simulate the major processes involved in charge generation, collection, transfer, multiplication, and readout as they would occur during operation of the detector. Noise processes such as dark current, clock induced charge, Fano noise, and read noise are also included within the model. The model has been designed to enable pixel-level properties and defects to be represented. Individual, pixel-to-pixel transfers within the simulated detector are modelled, allowing for custom read-out routines and procedures to be programmed into the model. This has enabled validation of the model by simulating camera characterization procedures to ensure realistic operation and output compared to a real EMCCD camera system tested in the lab. The MATLAB EMCCD model will be provided open-source to the community.