Time-Delay Integration EMCCD

Abstract

Scientific EMCCD cameras are the detector of choice for extreme low-light conditions. With photon counting capabilities, sub-electron readout noise and low dark current, EMCCDs can detect very faint signals. Traditionally, EMCCD are operated in frame-transfer mode where the image is integrated in the light-sensitive region of the sensor and then quickly transferred to a storage array before being read out. Time-Delay Integration (TDI) is a specialized readout mode optimized to image fast moving objects while preserving light sensitivity. By shifting the photoelectrons simultaneously to the movement of the object, TDI effectively increases the integration time available to collect light. The newest version of Nüvü Caméras’ CCD Controller for Counting Photons (CCCP) will allow operating EMCCD detectors using TDI readout mode with either internal or external trigger sources at more than 100k lines per second. The combination of TDI and EMCCD technologies represents a new leap for extreme low-light imaging in fast moving conditions opening EMCCD to a range of new applications.

I. ELECTRON MULTIPLYING CHARGE COUPLED DEVICES

Electron Multiplying Charge Coupled Devices (EMCCDs) are extremely sensitive devices capable of detecting a single photon in the visible spectrum. EMCCD cameras are based on a similar architecture to frame-transfer CCDs. An imaging area comprised of individual pixels are used to collect incoming light and trap resulting photoelectrons in the silicon substrate of the detector. One by one, each pixel line is shifted down and ultimately transferred to the horizontal register. A second high voltage serial multiplication register is then used to multiply the electrons from each pixel and propel the weak signals over the readout noise floor which allows for single photon sensitivity [1].

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