title: Measuring 0.1-nm motion in 1 ms in an optical microscope with differential back-focal-plane detection.
abstract: Back-focal-plane detection of micrometer-sized beads offers subnanometer resolution for single-molecule, optical trapping experiments. However, laser beam-pointing instability and mechanical drift of the microscope limit the resolution of optical-trapping experiments. By combining two infrared lasers with improved differential beam-pointing stability (< or = 0.05 microrad), we simultaneously measure and subtract the motion of the microscope stage, leading to a resolution of <0.1 nm in 1 ms and stability of 0.5 nm over 60 s. Repeated steps of 0.4 nm at 1 Hz are resolved with a signal-to-noise ratio of 25.
authors.affiliation: JILA, National Institute of Standards and Technology, Boulder, Colorado 80309-0440, USA.
authors.forename: Lora
authors.initials: L
authors.lastname: Nugent-Glandorf
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Perkins
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D008846:Micromanipulation / Q000295:instrumentation* / Q000379:methods; D008853:Microscopy / Q000295:instrumentation* / Q000379:methods; D009038:Motion; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D009862:Online Systems / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000295:instrumentation*