Signals and noise in micromechanical measurements.

Publisher Summary This chapter discusses the signals and noise in micromechanical measurements. A variety of single-molecule experiments, ranging from optical tweezers and scanned-tip microscopies to single-molecule fluorescence methods, have recently begun to explore the new territory. Researchers are faced with a multitude of challenging problems, one of which is noise that sets limits on the resolution of single-molecule measurement. Instrumentation must be designed with enough stability to make measurements on nm-length scales, and a thorough understanding of the subtleties of data analysis is necessary to push the limits of detection and to avoid artifacts. The chapter discusses noise issues mainly in the context of optical tweezers experiments, but much of the discussion applies to other micromechanical experiments as well. Optical tweezers, also known as laser trapping, is a micromechanical technique that is finding increasing use in a broad spectrum of experiments in biology. Optical trapping of particles uses the momentum transfer from light scattered or diffracted by an object immersed in a medium with an index of refraction different from its own.

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