title: A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization.
abstract: Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (1) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (2) minimizing sample motion relative to the optical trap using a three-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03-2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging.
authors.affiliation: JILA, National Institute of Standards and Technology, and University of Colorado, Boulder, CO, 80309, USA.|Department of Physics, University of Colorado, Boulder, CO, 80309, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Okoniewski
authors.affiliation: Department of Physics and Astronomy, Amherst College, Amherst, MA, 01002, USA.
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Carter
authors.affiliation: JILA, National Institute of Standards and Technology, and University of Colorado, Boulder, CO, 80309, USA. tperkins@jila.colorado.edu.|Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA. tperkins@jila.colorado.edu.
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Perkins
mesh_terms: D007834:Lasers; D008853:Microscopy / Q000295:instrumentation / Q000379:methods / Q000592:standards; D055100:Optical Fibers; D052898:Optical Tweezers; D055095:Optics and Photonics / Q000295:instrumentation / Q000379:methods / Q000592:standards
keywords: Active stabilization; Force spectroscopy; Optical trap; Optical tweezers; Single molecule