Braden Czapla is a mechanical engineer in the Dimensional Metrology Group at the National Institute of Standards and Technology (NIST). His primary research interests are in quantifying and improving the uncertainty of laser-based measurements of length, with a focus on terrestrial laser scanner technology and interferometer design. Additionally, he is the technical lead on NIST's Sphere Diameter by Interferometry calibration service. Prior to joining NIST, Braden earned his Ph.D. in mechanical engineering from Columbia University in 2019.
The National Institute of Standards and Technology Dimensional Metrology Group is responsible for disseminating the SI unit of length, the meter, to the United States manufacturing and scientific sectors. Of particular importance is providing ultralow measurement uncertainty on standard artifacts such as gage blocks and balls. In this talk, I will be describing the efforts we've made to characterize a Fizeau interferometer for the measurement of sphere diameter. These efforts resulted in a sub-10 nm expanded measurement uncertainty on typical 25 mm gage balls (Eric Stanfield et al 2020 Metrologia 57 025003). I will then cover on-going research efforts to use this instrument and a spherical contact method to measure the optical phase shift upon reflection, the largest length-independent contributor to measurement uncertainty for gage blocks.