This Small Business Innovation Research Phase I project is for research to develop an optical measuring device for simultaneously measuring the deflection basin caused by application of a heavy test wheel on standard road pavement and the pavement surface profile. The device is based on the laws of geometrical optics to measure the small deflections from a load wheel. The system relies on strong, monochromatic light sources from lasers and has the theoretical capability of accurately measuring deflections in the range of 5 to 30+ mils. Major advantages are: (1) the device has no moving parts; and (2) it measures the entire deflection basin while moving continuously at around10 mph. The proposed tests will evaluate its capability under realistic, but controlled conditions, using real pavement to evaluate its effectiveness on the variable surface conditions found on typical pavement. The optical deflectometer will be carefully tested and verified for accuracy in measuring deflections over the range of deflection expected in testing real pavements while moving over the surface. These tests include digital data recording of laboratory and simplified field data across the width of the deflection basin. This system will increase the efficiency of pavement maintenance inspection by a factor of four or five. It will measure the entire deflection basin, rather than the single point measurements obtained by today's equipment and simultaneously the pavement surface profile. This system will be highly desirable to all government and private agencies, both domestic, and foreign, who are responsible for pavement maintenance.
