Chapter 2 Basic Laser Tweezers

This chapter discusses the basic laser tweezers. The basic information for designing and building a laser tweezers system for force measurements is provided in the chapter. If force measurements are not required, then the considerations about the analysis system, a fine piezo stage, and stability are less important. For the initial alignment and characterization of the system, red blood cells provide an easily trapped sample. For a difficult test sample, the smaller latex beads are stable and easy to obtain. Anyone setting up laser tweezers is encouraged to see a working tweezers system and to compare samples with that system. This basic system would include a low-power infrared (IR) laser, mirrors, and focusing lenses, which can be added to a good research microscope. The major limitations of the basic system are the laser power and stability needed for force measurements, and the proper laser beam configuration required for trapping small particles.