Method for imaging a molecular strand (MS), the method comprising - providing a sample volume (SV) comprising the strand (MS) with trapping beads (BD) attached on opposite ends of the strand (MS); and - providing an excitation beam (EB) having an excitation focus (EF) in the sample volume (SV) wherein an excitation of a fluorophore (FL) on the strand (MS) by the excitation focus (EF) results in a fluorescence response (FR) when the excitation focus (EF) coincides with the fluorophore (FL); characterized in that the method further comprises the following steps: - scanning the excitation focus (EF) in the sample volume (SV) along a one dimensional scanning line (SL); - providing optical traps (OT), trapping the trapping beads (BD) at the ends of the strand (MS) in the sample volume (SV) and extending the strand (MS) between the optical traps (OT) to form a one-dimensional trapping line (LL) parallel to the one-dimensional scanning line (SL); - aligning the one-dimensional trapping line (LL) to coincide with the one-dimensional 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 one-dimensional scanning line (SL). - providing a sample volume (SV) comprising the strand (MS) with trapping beads (BD) attached on opposite ends of the strand (MS); and - providing an excitation beam (EB) having an excitation focus (EF) in the sample volume (SV) wherein an excitation of a fluorophore (FL) on the strand (MS) by the excitation focus (EF) results in a fluorescence response (FR) when the excitation focus (EF) coincides with the fluorophore (FL); characterized in that the method further comprises the following steps: - scanning the excitation focus (EF) in the sample volume (SV) along a one dimensional scanning line (SL); - providing optical traps (OT), trapping the trapping beads (BD) at the ends of the strand (MS) in the sample volume (SV) and extending the strand (MS) between the optical traps (OT) to form a one-dimensional trapping line (LL) parallel to the one-dimensional scanning line (SL); - aligning the one-dimensional trapping line (LL) to coincide with the one-dimensional 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 one-dimensional scanning line (SL). - scanning the excitation focus (EF) in the sample volume (SV) along a one dimensional scanning line (SL); - providing optical traps (OT), trapping the trapping beads (BD) at the ends of the strand (MS) in the sample volume (SV) and extending the strand (MS) between the optical traps (OT) to form a one-dimensional trapping line (LL) parallel to the one-dimensional scanning line (SL); - aligning the one-dimensional trapping line (LL) to coincide with the one-dimensional 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 one-dimensional scanning line (SL). <EOS>