"Calibration of optical tweezers with positional detection in the back focal plane", REVIEW OF SCIENTIFIC INSTRUMENTS 77, 103101 (2006)
"Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?", Biophysical Journal 107, 1474–1484 (2014)
This active power-spectrum method has several advantages, particularly relative to the assumptions required for the passive power spectrum: 1), it is able to determine trap stiffness k and converting factor b simultaneously, 2), it does not require prior knowledge of viscosity of the medium, the size of the bead, or the height of the trapped object above the surface; and 3), it is less sensitive to temperature changes. It is insensitive to system noise, its result inherently includes the output of the passive power-spectrum method, and it allows simultaneous measurement of b and k.
"Calibration of Optical Tweezers for In Vivo Force Measurements: How do Different Approaches Compare?", Biophysical Journal 107, 1474–1484 (2014)
This active power-spectrum method has several advantages, particularly relative to the assumptions required for the passive power spectrum: 1), it is able to determine trap stiffness k and converting factor b simultaneously, 2), it does not require prior knowledge of viscosity of the medium, the size of the bead, or the height of the trapped object above the surface; and 3), it is less sensitive to temperature changes. It is insensitive to system noise, its result inherently includes the output of the passive power-spectrum method, and it allows simultaneous measurement of b and k.