Optical Trap Kit
19590-D04-V15; Apr 12, 2012
Page 11
www.thorlabs.com
Part 5.
Optical Force Measurement Module OTKBFM (optional)
The OTKBFM module contains the components that can be used to calibrate the trap using positional
detection of the back-focal plane of the condenser. By placing the Quadrant Position Detector (QPD) in
a plane conjugate to the back focal plane of the condenser, the signal generated by the QPD is sensitive
to the relative displacement of the trapped particle from the laser beam axis. As a result the output of the
detector can be used to calibrate the position, stiffness, and force of the optical trap. The detector is
connected to the cage cube above the condenser as in Figure 3.2. A TQD001 T-Cube Quadrant Detector
Reader and two T-Cube Strain Gauge Readers are the main components included in this module. For
high bandwidth measurements the QPD signal can be read out from the controller cube directly via a
DAQ card (not included).
Figure 4.1: Force Measurement Module OTKBFM consisting of two TGS001, TQD001,
PDQ80A and the cage assembly for connecting the detector and optics to the base kit. The shaded
controllers and the USB hub TCH002 are included with the base kit OTKB
