Dimensional Metrology Program

Addressing selected needs in dimensional metrology over length scales ranging from micrometers to kilometers. This includes calibrations of measuring instruments such as laser interferometers and laser trackers, a wide array of engineering gauges, standard reference materials, and specialized measurements, e.g., high accuracy coordinate measuring machines (CMMs). The program also provides expertise and representation of U.S. interests in national and international standards committees. The DMP frequently provides metrology expertise to other government agencies including The Department of Defense (DOD), Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and National Institute of Justice (NIJ).

Since its inception, one of NIST’s duties has been to provide measurements for the units of length, weight, and time, and this remains a crucial task today. From calibrating kilometer-long master standards for measuring the lengths of fiber optic cables to determining new ways to measure microscale features on car fuel injectors, NIST continues to provide the last word on length measurements – data that can be worth millions of dollars to companies and consumers.

Improving measurements and calibrating standards are larger undertakings than most companies can tackle, but they represent an ideal niche for a neutral third party such as NIST, given its mandate to promote competitiveness in US industries. With decades of experience improving both measurements and the tools industry uses to make those measurements, this program provides a service that no other institution can offer.

At the simplest though still exacting level, NIST provides calibration to those companies and institutions where accuracy has far-reaching consequences. For example, calibrating the master tapes for a company that makes tape measures means more accurate products for countless surveyors, petroleum engineers and contractors, as well as ordinary home-owners. Because a single master tape calibration applies to millions of production tapes, each used innumerable times, a single NIST calibration leads to a huge pay-off.

Program researchers also work to improve calibration at the smallest scales, providing methods that yield uncertainties of less than 100 nanometers -- 0.1% of the width of a human hair. NIST’s high accuracy equipment can achieve this accuracy when measuring the distance between two points, but when precise measurements are needed in three dimensions, the task is much harder. For example, fuel injector plungers, the tiny cylinders that go in and out of bores on a car’s fuel injector, must be exactly cylindrical and have exactly same size along their entire length. To tackle such measurements, the project will use next generation coordinate-measuring machines, hopefully leading to improvements in 3-dimensional precision that can lead to gigantic fuel savings for car-buyers. Indeed, it is this kind of error-reduction on microscales that over the last 30 years has changed the time between car repairs from some 30,000 miles to as much as 200,000 miles – another cost saver. Also on the micrometer scale, the program seeks to improve measurement of the topography of surfaces – a boon to crime labs, for one, by allowing the patterns on bullets and shell casings to be matched with greater reliability. NIST also serves the needs of the telecom industry by calibrating micro-optical components used to connect together miles of fiber optic cables.

Another key part of the program’s mission is the continuous improvement of fundamental dimensional measurement techniques. NIST leverages recent advances in optical physics to try to improve the accuracy of meter measurement from its current uncertainty of several parts in 100 million. Ultimately these tools could be used in situ, allowing industry to perform its own precise measurements. Such standards might even be delivered to a manufacturer’s doorstep by transmitting precise wavelengths of light though the optical fiber telecommunication network.

• Implemented a comprehensive quality system for all PED dimensional calibrations resulting in conformity with international accreditation practices.
• Developed the NIST micro-feature probe that provides the most accurate dimensional measurement of features in the 50 mm to 100 mm size range in the world.
• Harmonized the U.S. with the ISO standards for coordinate measuring machines by producing major revisions to both documents resulting in lower costs to U.S. manufacturing companies.