User:Pranav Rathi/Notebook/OT/2012/11/13/Optical Tweezers Calibration
To perform accurate measurements with optical tweezers, it is necessary to calibrate some experimental parameters and even before that study the active components of the optical tweezers setup. The parameters I want to calibrate: Stiffness; which measures the force that is exerts on the trapped bead, and Sensitivity; which measures the relative position of bead within the trap. The components I want to study: Laser, AOM (acoustooptic module), microscope objective, QPD (quadrant photo diode), z and x piezo. It is necessary to characterize these components first because not only they affect the experimental parameters but also reduce the chances to see something unexpected in data later on.
I characterized most of the active components in the setup starting with the laser.
It is important to know some facts about the laser used in the setup. I did not do a rigorous study (because it was not necessary), just specified few parameters like power output, beam waist and its location, polarization, beam mode profile and beam propagation factor. I used this information to design the tweezers. The laser specification are given in the following link: