Optical Interferometer

Optical Interferometer Summary: The instrumentation consists of Bruker Nano Inc. OM-NPFLEX 3D Metrology System and associated accessories. The optical interferometer employs coherence scanning interferometry to produce 3-D surface maps for investigation of surface topographies for a wide variety of natural or engineered, inorganic, or organic materials. The instrument allows for 3-D non-contact determination of topographical characteristics over a vertical measurement range of 0.1 nm to 10 mm with a vertical resolution less than 0.15 nm. The lateral spatial sampling range is 0.1 to 13.2 mm and the maximum field of view is 7.7 x 5.8 mm. Individual measurements can be combined by stitching multiple images to cover large surface areas. Measurable sample dimensions are 350 mm (249 mm with automated stage) H x 304 mm D x 304 mm W.

The capability for testing large specimens, unique for an interferometer, allows for measurement of various materials such as rocks, concrete cylinders, structural components (e.g., beams), and pavement cores directly without a requirement for cutting coupon samples or trimming samples obtained in the laboratory or the field to produce small specimens for surface analysis. The configuration does not compromise the ability to test small samples. Full sample and non-contact testing allows for repeated surface texture characterization during service or structural and/or environmental conditioning. In addition, a system option that permits 90° swivel rotation of the optical metrology head is included to access sample sides and angled surfaces.

The combined large working distance and swivel action head represents the most flexible configuration for an interferometric surface profiling system. The non-contact nature of interferometry and large working table and swivel action head capabilities of this device are crucial in preserving surfaces for characterization subsequent to testing or service use and also as part of forensic analysis. A thermal stage accessory is also included to measure surface characteristics as a function of temperature. The option includes two wide temperature range (80 to 580K) thermal stages and a programmable temperature controller.  In addition to 3-D measurements, 2-D profile measurements can be conducted using the interferometer. Surface characteristics that can be determined include amplitude, spacing, hybrid (amplitude and spacing such as slope), and functional (e.g., friction, contact applications) parameters. Analyses of interface shear behavior of layered systems; soil-structure interaction; discrete inclusions in composite systems; packing arrangements; deposition characteristics, etc. can be significantly improved and new knowledge generated with surface analysis.