Figure 8.8 — Alignment of the laser beam to generate an optical tweezers

Fig. 8.8 — Alignment of the laser beam to generate an optical tweezers
Figure 8.8 — Alignment of the laser beam to generate an optical tweezers. (a) The laser head is firmly clamped on the optical table and the laser beam is prepared by using two polarisers and a half-wave plate to control the beam power without changing the laser power setting (a filter is also added in the camera path to prevent the laser light from reaching the camera); (b) a series of mirrors (M4, M5 and DM6) are added to guide the beam through the objective in order to generate the optical trap; (c) a telescope (constituted by lenses L1 and L2 ) is added to increase the beam waist size and overfill the objective back aperture. (d) Corresponding schematic of the optical tweezers set-up.