Original Date: 11/03/1996
Revision Date: 01/18/2007
Best Practice : Optical Metrology
Optical diagnostics offer industrial advantages for today’s challenging environments. Optical measurements require no contact with the unit under evaluation, use non-invasive measurements, furnish high resolution over a wide range, and provide multiple measurement strategies. In addition, optical measurements prove to be useful in areas of limited access or where contact could create difficulties.
Oak Ridge National Laboratory’s (ORNL’s) Center for Manufacturing Technology Metrology offers a wide variety of technologies for optical diagnostics. The Center illustrates its expertise by deploying measurement systems into challenging environments. Optical applications, developed by ORNL, exist in today’s industries for use with interferometers, holographs, and laser micrometry.
ORNL developed interferometric applications for manufacturing environments, steam-powered generating stations, and high resolution laboratory measurement systems. One method uses interferometry to monitor the amount of moisture contained in steam which is directly related to the efficiency and safety of steam-powered generation stations.
Holographs provide a reference point for subsequent images at submicron accuracy. The Center can provide and store real-time data for comparing and measuring mechanical or thermal stresses by using an integral vision system. Provided with technical expertise from ORNL, Diffraction International evaluated and resolved any problems with the computer generated hologram (CGH) null adapter prototype. This led to the successful introduction of a commercial CGH null adapter. By using standard commercial equipment, this adapter can provide an accurate and less-expensive means for testing aspheric-optical surfaces. ORNL now provides optical metrology technology and expertise for measuring and testing precision, aspheric-optical surfaces with CGH null adapters.
ORNL developed a laser micrometry method which simultaneously measures the size and weight of a ceramic component as it dries. This method provides a high resolution record of component drying characteristics. Through its laser micrometry research, ORNL showed that the manufacturing ceramic baking time (for curing) can be shortened without degrading component reliability.
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