Laser Scanning Optical Trapping System
Measurement of defect line tension.
The set-up allows three dimensional (3D) optical trapping implemented using an electrically addressed spatial light modulator along with 3D imaging of the sample using fluorescence confocal polarizing microscopy (FCPM). The beam from a 1064 nm CW laser is first expanded by a telescope in the optical to match the beam size to the active area of the electrically-controlled, phase-only spatial light modulator (SLM). Upon being reflected off the SLM, the beam is again resized to overfill the back-aperture of the microscope objective. FCPM imaging can be performed in three channels using one of the five laser-lines for dye-excitation. The dichroic mirror allows the trapping IR beam to be reflected to the sample while transmits the visible light used for imaging. [L1 (f1 = 100 mm), L2 (f2 = 250 mm), L3 (f3 = 850 mm), and L4 (f4 = 400 mm) are plano-convex lenses with anti reflection coating for 1064 nm. P is a Glan-Laser polarizer for 1064 nm; SLM is the spatial light modulator; HWP is a half waveplate; DM is the dichroic mirror; MO is the microscope objective]
Zhiyuan Qi and Yiheng Lin aligning an XY laser scanning optical trapping system.