U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Physical Measurement Laboratory

PML is a world leader in the science of measurement. We determine the definitive methods for nearly every kind of measurement employed in commerce and research, provide NIST-traceable calibrations, and disseminate standards and best practices throughout the nation. At the same time, PML works continuously at the outermost frontiers of metrology, devising tools and techniques to meet the ever-changing demands of American industry and science.

Banner image with floating telescope in space and large Purple wavy line in the middle.
Measuring The Cosmos

Notice:

Beginning November 15, 2021, WWV and WWVH will be broadcasting a test signal on minute 8 of each hour on WWV, and minute 48 on WWVH. This signal has been created to assist in ionospheric research, and is a joint effort of the Ham Radio Citizen Science Investigation (HamSCI) and NIST. The signal consists of various tones, chirps, and Gaussian noise bursts. The signal may be modified occasionally. For more information on HamSCI and the WWV/WWVH project, click here.

SI Redefinition

Outer circle has one wedge for each of the 7 SI units (kilogram, meter, second, ampere, kelvin, mole, and candela) and the inner circle has wedges for the 7 important constants.
Credit: BIPM

On May 20, 2019, the world metrology community dramatically redefined four of the seven base units of the International System of Units (SI), with the result that for the first time each unit is based on a fixed value of a fundamental constant of nature. Years of PML advances at the frontier of measurement science were critical to that outcome.

Learn more about these efforts at the SI Redefinition Portal.

News and Updates

Events

Industry Impacts

A streaked image of a taxi and a dark car driving in Times Square, New York City street at night.

Fare Standards for Rideshare Services

To calculate fares, app-based ride services such as Lyft and Uber don’t use traditional taxi meters, but instead combine data from GPS and cellular networks to
Illustrative subset of parameterized shapes available for nanoscale photonic, electronic, mechanic, fluidic, and other applications.

Nanolithography Design Tools

Accurate production of nanoscale features on semiconductor chips is essential to their performance, but typical design tools cater to the dominance of straight
Image of a radiation pressure power meter

High-Power Lasers for Manufacturing 

Measuring the intensity of high-power lasers used by manufacturers for precision cutting and welding can be difficult due to large instrumentation challenges
atom-based magnetic sensor

Brain Mapping Technologies

Magnetic signals produced by electrical currents in the brain can be used to map brain processes and help in the diagnosis and treatment of disease

Awards

2021 AVS Fellow - Robert Ilic

For creation of a revolutionary GDSII CAD design program and fundamental contributions to the understanding of surface functionalization
View All Awards

Press Coverage

Patents

A timeline of long distance communication techniques

Communication Linker for Communication Linking

NIST Inventors
Sergey Polyakov and Ivan Burenkov
Patent Description The US has the leading optical communication industry and one of the largest telecommunication markets. Our invention directly improves the underlying technology of the telecommunication infrastructure. Quantum Coherent Frequency Shift Keying (CFSK) receiver is a device that

Optical Phantom for Producing a Time-Resolved Diffuse Reflectance Spectrum

NIST Inventors
Jeeseong C. Hwang
Patent Description Physikalisch-Technische Bundesanstalt (PTB) and NIST jointly developed a concept for a waveform synthesizer which can generate a controlled waveform with several picosecond (ps) time resolution. In a light-diffusing material, characteristics of the time-of-flight distribution (e.g
Line drawing of the thermal impedance amplifier

Thermal Impedance Amplifier

NIST Inventors
Adam McCaughan, Varun Verma, Sonia Buckley and Sae Woo Nam
Patent Description Presently, superconducting electronics are being applied to areas such as computational backends for future quantum processors, high-performance supercomputing, and ultrafast digital signal processing. In all of these areas, data must be communicated between the superconducting
This image of a chart titled "How does it work" that describes the optomechanical reference.

Optomechanical Reference

NIST Inventors
Gordon A. Shaw and Jacob Taylor
A mechanical sensor incorporating an optical cavity is used to provide a mass and/or force reference from a known or characterized circulating optical power in the optical cavity. The radiation pressure force in the optical cavity is used to actuate the mechanical sensor. The optical cavity in put

Contacts

PML Director and PML Deputy Director

Associate Director for Measurement Services and Associate Director

Executive Secretaries to Director Kushmerick and Deputy Director Williams