PHOTONIC FORCE MICROSCOPE CALIBRATION BY THERMAL NOISE-ANALYSIS

The forces of a photonic force microscope based on optical tweezers ar e determined using the Boltzmann distribution of thermally driven posi tion fluctuations. As a fundamental method, only a minimum of informat ion about the system is required, i.e. the solution's temperature. Thi s calibration method provides detailed information about the trapping potential with nanometer resolution. In contrast to other calibration methods, no numerical hydrodynamic corrections are necessary. The late ral force constant of the optical trap was measured along the optical axis and found to decrease linearly by approximate to 8%/mu m for a la tex bead 600 nm in diameter. Oscillations in the lateral force constan t were found along the optical axis close to the surface.