Smart Readout of Nondestructive Image Sensors with Single Photon-Electron Sensitivity

Abstract

Image sensors with nondestructive charge readout provide single-photon or single-electron sensitivity, but at the cost of long readout times. We present a smart readout technique to allow the use of these sensors in visible light and other applications that require faster readout times. The method optimizes the readout noise and time by changing the number of times pixels are read out either statically, by defining an arbitrary number of regions of interest in the array, or dynamically, depending on the charge or energy of interest in the pixel. This technique is tested in a Skipper CCD showing that it is possible to obtain deep subelectron noise, and therefore, high resolution of quantized charge, while dynamically changing the readout noise of the sensor. These faster, low noise readout techniques show that the skipper CCD is a competitive technology even where other technologies such as electron multiplier charge coupled devices, silicon photo multipliers, etc. are currently used. This technique could allow skipper CCDs to benefit new astronomical instruments, quantum imaging, exoplanet search and study, and quantum metrology.

Constraints on the electron-hole pair creation energy and Fano factor below 150 eV from Compton scattering in a Skipper-CCD

“…A plausible hypothesis of this discrepancy is the high rate of single-electron events that contributes to the measured cluster energy. Controlling the rate of single electrons by reducing the image occupancy and optimizing the CCD operation [28,33] are the next steps towards a precision measurement of the electronhole pair creation energy and Fano factor below 150 eV using Compton scattering in Skipper-CCDs.…”

Characterization and Optimization of Skipper CCDs for the SOAR Integral Field Spectrograph

“…In both instances, an optimum was found at σ N ∼ 0.5 e − rms pixel −1 , assuming that only 5% of the detector pixels need to be read with the improved signal-to-noise. It would take ∼40 minutes to achieve ∼0.5 e − rms pixel −1 in all detector pixels, and we attempt to shorten these long readout times by exploiting the region of interest (ROI) capability of the Skipper CCD (Drlica-Wagner et al 2020; Chierchie et al 2021). We can define a geometrical area on the Skipper CCD (e.g., 5% of the detector area) that is read with multiple samples.…”

Review of Quanta Image Sensors for Ultralow-Light Imaging

“…In principle, any device that can detect photoelectrons with less than 0.15-0.30e − rms read noise to achieve low BER (i.e., BER < 0.0005-0.005 bit-errors/read) can be used as a QIS device. For example, a cooled EMCCD [12] can operate as a 1bQIS, albeit with a slower readout rate (but not so well as a mbQIS due to gain noise), and a cooled CCD with "skipper readout" (many nondestructive reads of a pixel) can also be used as 1bQIS or mbQIS, albeit with an even lower frame rate [27].…”