A dual-threshold method for photon counting imaging with the EMCCD

A dual-threshold method is proposed in this paper to reduce the spurious photon events in photon counting imaging with a thermoelectric cooling electron multiplying charge coupled device (EMCCD). Using the thresholds in both spatial and time domains, the read noise, dark signal and clock induced charges (CIC) can be filtered simultaneously. The theory and measurements of the dual-threshold technique are presented. The results show that this method works better than 5σ threshold method in restoring photon images with the EMCCD of the working temperature at -20 °C. The sensitivity of thermoelectric cooling EMCCDs can be effectively improved by the dual-threshold technique. Photon images could be still restored under the illumination level of 0.1e-/pixel/frame.