Characterization of the Dimensions of Internal Gap in a Glass Artifact Using a Laser Triangulation Probe

The National Institute of Standards and Technology (NIST) Dimensional Metrology Group (DMG) develops and delivers unique and critical high-value dimensional measurements that promote industry innovation, ensure product quality, and are not commercially available. In some cases, we need to use multiple measuring systems to provide our customers with the needed measurement results. This paper is the story of one of these measurements that involved a number of different instruments and is typical of the complexity of many of our customer requests. Recently, NIST provided a measurement solution for characterizing the gap width of a new biotechnology absorbance spectrometry standard reference material (SRM). This SRM is a reduced path length validation absorption standard for Ultraviolet (UV) visible spectroscopic measurements. The SRM consists of a series of very small rectangular glass containers called cuvettes and has been developed for the biotechnology community’s daily measurements of samples where the sample amount available is very limited: typically, samples include DNA, RNA, or an antibody. Identification of the exact substance by spectrometry measurements is based on how the substance absorbs light. The dimension of the gap between the inside walls of the cuvette is a critical characterization, therefore measurement of the gap width with low uncertainty is required.