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| Figure 2: Schematic diagram of the optical tweezers system with the image acquisition arrangement for detecting Brownian motion before and after cFIR irradiation, where the laser beam is expanded fivefold with lens pairs (L1:L2) to slightly overfill the back aperture of the objective lens (Plan Apo 60x/1.40 oil, Nikon), and directed into objective lens via a dichroic mirror D1 (780dcspxr, Chroma). Here we apply Fourier-based cross-correlation processing to determine the lateral displacement of the optically trapped bead; therefore, both the mean square displacement (MSD) and the diffusion coefficient (D) can be obtained. |
