Experimental dynamic range (DR_s) evolution versus co-phasing cycle number obtained from the short-exposure images acquired with the THT test-bench operating in the photon-counting regime. The observed object is a point-like source. Two photon flux are investigated (200 and 500 photons/frame). The co-phasing algorithm works with the photon-counting regime data. The DR_s is measured with the high flux level data. The mean values of DR_s are equal to 1000 for 200 photons/frame and 1700 for 500.