2020-06-03

Space & Defense

Over the past centuries, space exploration has always sought state-of-the-art low-light imaging technology and adopted many innovative products to carry out its never-ending discovery of the cosmos.

The colossal potential of this technology is starting to emerge and yet needs to be fully grasped. The following EMCCD ground and space-based applications are only the tips of the iceberg.

Space & Defense
Credit: NASA

Imaging devices with the lowest possible readout noise are paramount for high quality observation not limited by background or shot noise. In that regard, the EMCCD’s sub-electron readout noise makes it the ideal candidate for low light imaging applications. However, due to the stochastic nature of the electron-multiplying gain that counters readout noise, EMCCDs are flawed with an Excess Noise Factor (ENF) that has the same effect on the signal-to-noise ratio as halving the camera Quantum Efficiency (QE).

To recover the acquisition system’s full capabilities, it is possible to operate in Photon Counting mode in which a signal as little as a single photon per pixel per image can be recorded. For greater dynamic range, images can be superimposed and the threshold adjusted accordingly. In this context, EMCCDs are to be used for imaging very faint light sources and/or at considerable high speeds. The latter case however produces spurious charges, also referred to as clock-induced charges (CIC), which becomes the dominant noise source in EMCCDs. With high CIC levels and insufficient electron-multiplying gain, it is futile to operate the camera in Photon Counting mode.

Nüvü Camēras’ CCCP controller (CCD Controller for Counting Photons) arises from an academic research endeavour. It was developed from the ground up with the objective of elegantly mastering the major noise source in Photon Counting applications, the CIC. The CCCP is best suited for the modern astronomer needs as it produces significantly less CIC, which allows efficient use of a higher  EM gain and makes a key difference in imaging performances.

With that much less noise, there are virtually no disadvantages to take high-resolution images and post-process them in order to select the desired SNR and/or spectral resolution. In fact, this is changing the way astronomers use spectroscopy, as one can choose to bin frames temporally or spectrally to any desired extent while keeping track of the higher dynamics inside the high-resolution original images.