AN ULTRA HIGH ACCURACY 1D LASER-BASED MICROMETER FOR DIAMETER MEASUREMENT
John R. Stoup
The Dimensional Metrology Group at the National Institute of Standards and Technology (NIST) has developed an ultra-high accuracy laser micrometer capable of external diameter measurements with a targeted expanded uncertainty (k=2) of less than 20 nanometers. This instrument is an extended development of a design developed by NIST in the 1990s and has been continuously improved since its inception. This newest design takes advantage of the lessons learned through two decades of operation, process control measurements and analysis to advance the state of the art for diameter measurements within an artifact diameter range of 0.02 to 55 millimeters. The instrument makes use of low thermal expansion materials, a stable structural design, environmental control, and remote manipulation of the artifacts to address the limiting uncertainty components contained in the previous NIST 1D micrometer uncertainty budget. A review of the instrument development and components will be presented. The anticipated operational measurement uncertainty budget for this new instrument will be outlined along with the high accuracy applications that will benefit from this effort.