Inspection and profiling of moving objects using a TDI camera

Abstract

Surveying deformation of propeller blade under hydrodynamical load is a factual engineering problem when propeller has been developed to a certain stage. This paper develops a photoelectronic method based on subpixel high precision object position surveying. A thin laser beam is incident upon a small reflector adhered to the surveying point on blade, the reflected light is focused on a frosted glass and there appears a facula. The angular deformation of the surveying point causes the facula to move and the motion is detected by an image processing system. The relationship between the motion and the angular deformation under the influence of refraction index is given. The flash method and the facula image grab are also discussed. Finally, angular deformation of 48 surveying points of a highly skewed propeller model of a 2800 TEU container ship under mooring status rotating at 500 and 750 rpm are successfully obtained.