The present disclosure concerns a method and system for imaging a molecular strand (MS). The method comprises providing a sample volume (SV) comprising the strand (MS); providing an excitation beam (EB) having an excitation focus (EF) in the sample volume (SV); scanning the excitation focus (EF) in the sample volume (SV) along a one dimensional scanning line (SL); trapping an end of the strand (MS) in the sample volume (SV) and extending the strand (MS) along a one-dimensional trapping line (LL) parallel to the scanning line (SL); aligning the trapping line (LL) to coincide with the scanning line (SL) to have the scanning excitation focus (EF) coincide with the strand (MS); and recording the fluorescence response (FR) as a function of a plurality of distinct scanning positions (X0) of the excitation focus (EF) along the scanning line (SL).