1. Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Stop 8615, Gaithersburg, MD 20899-8615, USA
2. Google, 1600 Amphitheater Pkwy., Mountain View, CA 94043, USA
3. Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Stop 8615, Gaithersburg, MD 20899-8615, USA (Corresponding author), e-mail: christopher.white@nist.gov, https://orcid.org/0000-0003-1285-4460