I-Corps: Fringe Projection Profilometry for Precision Surface Metrology

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The broader impact/commercial potential of this I-Corps project is the development of a rapid measuring system for precision curved surfaces. The proposed technology is aimed at the design and fabrication of submillimeter radio telescopes and satellite communication antennas, which require tight surface tolerances, with panels produced in large quantities according to strict surface accuracy requirements. There are currently many methods used for measuring surfaces with high accuracy. However, they are limited on size, spatial resolution, and sensitivity to contact. Other methods such as coordinate measuring machines (CMM) and laser trackers, involve single point measurements and, therefore, are very slow. The proposed technology is designed to measure meter-scale areas with sub-millimeter spatial resolution and with extreme accuracy in a few minutes. In addition, the proposed technology may be used the alignment of a final assembled reflector dish, which is generally done using holography or commercial photogrammetry systems with manual fiducials. Both applications require significant preparation time, hardware, and an available satellite beacon signal in the case of the holography method. Radio telescopes of the future will require higher accuracy, larger dishes, and in higher quantities. This I-Corps project is based on the development of fringe projection photogrammetry. The proposed technology uses inexpensive, off-the-shelf hardware to rapidly measure freeform curved surfaces in high resolution. The technology works by projecting a series of fringe patterns onto the curved surface to be measured. Two cameras use stereo vision to triangulate the location of features in the projected patterns in three-dimensional space. Proprietary algorithms process images recorded by the cameras to generate a dense cloud of points with three dimensional coordinates that map the shape of the surface. This entire process takes only a few minutes and does not require custom optics or hardware based on the shape to be measured. This makes the proposed technology optimal for high volume, mass customization fabrication processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.