Showing papers on "Optical stretcher published in 2003"

Optical-trap force transducer that operates by direct measurement of light momentum.

Abstract: Publisher Summary This chapter describes the optical-trap force transducer that operates by the direct measurement of light momentum. By focusing a laser beam through a microscope objective, it has been found that particles with high indexes of refraction—such as glass, plastic, or oil droplets—are attracted to intense regions in the beam and could be held permanently at a focal point. Optical tweezers are useful in molecular and cell biology because several important forces are in an accessible piconewton (pN) range—for example, ligand-receptor binding, DNA stretching, protein unfolding, and molecular motor stall forces. Methods to measure such forces in the optical trap are under continuous development. The position of a spherical bead inside a trap can be measured with subnanometer precision by one of several optical methods, and so this technique has proven very effective. Methods to measure such forces in the optical trap have been under continuous development. Most force-measurement methods treat the optical trap as a harmonic potential well or virtual spring that pulls the bead toward the trap center.

Mechanical effects of light and measurement of optical trapping force

Abstract: An experiment that shows visually the mechanical effect of light using the optical tweezers is introduced. The background and the purpose to develop the experiment are discussed briefly. The principle and the equipment of the optical tweezers are described. The method of measurement of the optical trapping force is also provided. Finally a practical experiment scheme is introduced.