SCM Webinar

Optical tweezers is a very useful tool for manipulating objects. Of the six degrees of freedom, all the three translational degrees of freedom had been extensively studied. The exploration of the rotational degrees of freedom started recently, and the yaw rotation (In-plane rotation according to the airplane nomenclature) is more explored compared to the pitch and roll (first and second out-of-plane rotations.) 

Firstly we have studied the rotations of the birefringent particle in yaw and then explored the first out-of-plane rotation. We checked the suitability of the cylindrical approximation for spherical particles executing yaw rotation and found that the approximation holds good till the early Mie regime. Then we found a new way to rotate a birefringent particle in yaw with low ellipticity beams. We saw that the 3-micron sized birefringent particle starts to rotate when using orthogonal lasers of equal power. After that, we moved on to apply these rotations to study soft matter systems. We studied the adhesivity of surfaces using yaw rotations with a birefringent probe and then moved on to detect pitch motion at high resolution to explore cell biological applications. Lastly, we used the translation motion of a polystyrene particle to calibrate optical tweezers inside cells in view of the rotational calibration which we propose as future work.