Optical Laser Micro-Tweezwers System Using Laser Diode

A laser micro-tweezers system was constructed by combining a laser diode and an optical microscope equipped with long working distance objective lenses. The trapping characteristics of the system was investigated using a polystyrene sphere of 5 μm diameter. The experimental results showed that a polystyrene particle can be trapped and manipulated by the focused laser beam. Also, the rotation of a piece of ceramic sample was observed. It was shown that the trapping force linearly increases with the laser power, and that the minimum laser power for trapping a polystyrene particle with the objective lens (magnification=100, numerical aperture=0.75, working distance=4.7mm) is 3 mW. Trapping of several samples, such as yeast cell and potato starch is also shown