arXiv subjects

Gordon A. Shaw

Publications and source records attributed to Gordon A. Shaw.

3 recordsLinked to original sources

arXiv2022

Milligram mass metrology for quantitative deposition of liquid samples

Quantitative dispensing of liquids by mass becomes increasingly difficult as sample volume decreases. Whereas ml quantities of liquid can be directly weighed as dispensed on an analytical balance or using pycnometer methods, μl samples are more challenging due to their milligram-scale mass and rapid evaporation. Here, a method for quantitative determination of the mass of 1 μl droplets of liquid is proposed. The weighing of a microcapillary pycnometer combined with traceable calibration masses and corrections for sample evaporation allows determination of the droplet mass on the order of 1 mg with relative combined expanded uncertainty of 0.3 %.

physics.ins-det↗

arXiv2019

Meta-study of laser power calibrations ranging 20 orders of magnitude with traceability to the kilogram

Laser power metrology at the National Institute of Standards and Technology (NIST) ranges 20 orders of magnitude from photon-counting (1000 photons/s) to 100 kW (10^23 photons/s at a wavelength of 1070 nm). As a part of routine practices, we perform internal (unpublished) comparisons between our various power meters to verify correct operation.

physics.ins-det↗

arXiv2014

A self-calibrating optomechanical force sensor with femtonewton resolution

We report the development of an ultrasensitive optomechanical sensor designed to improve the accuracy and precision of force measurements with atomic force microscopy. The sensors reach quality factors of 4.3x10^6 and force resolution on the femtonewton scale at room temperature. Self-calibration of the sensor is accomplished using radiation pressure to create a reference force. Self-calibration enables in situ calibration of the sensor in extreme environments, such as cryogenic ultra-high vacuum. The senor technology presents a viable route to force measurements at the atomic scale with uncertainties below the percent level.

cond-mat.mes-hall↗