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Schematic showing the concept of optically trapped cantilevers.
Schematic layout of cantilever trapping and detection system. A Raman laser operating at is coupled into port 1 of a fiber optic circulator. The beam at the port 2 output of the circulator is collimated, directed to a standard inverted optical tweezer setup and brought to trapping focus by a 0.65 NA objective lens. Light backscattered from the cantilever is coupled confocally back into port 2 of the circulator and is delivered via port 3 to a detector. The dichroic mirror is a high reflector for the laser light, but transmits visible light from the microscope to the charge-coupled device (CCD) camera.
Silica cantilever trapping efficiency. Solid line: Trapping efficiency of cantilever as a function of transverse displacement of cantilever from the axis of trapping beam. Dashed line: Theoretical trapping efficiency based on geometrical optics model.
Confocal backscattered signal from cantilever when excited by laser beam chopped at .
Physical properties of long cantilevers in water with square cross sections. The trapping spring constant is calculated for a trapping beam.
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