Patent ID: 8290246

Claim:
A system for measuring recession of an ablative surface during testing in an arcjet facility, the system comprising: (1) at least first and second cameras, positioned in or adjacent to an arcjet facility so that each camera views an ablating surface of a test article, having an arbitrary shape, from a different direction, and so that each of the at least first and second cameras acquires time-synchronized images of the ablating surface at a sequence of spaced apart imaging times during which the ablating surface is exposed to flow of a heated fluid in the arcjet facility and thereby undergoes ablation; (2) a calibration mechanism for providing camera calibration coefficients for each of the at least first and second cameras by imaging a three dimensional calibration object and determining approximate transformations between two dimensional image-plane coordinates and three-dimensional physical object-space coordinates; (3) a three dimensional surface grid of nodes that conforms to an initial shape of the ablating surface, to define measurement points on the ablating surface; and (4) a computer that is programmed: (a) to define image-plane coordinates for corresponding measurement points for each of the at least first and second cameras by mapping the nodes of the surface grid from the physical object-space coordinates to the image-plane coordinates for each of the at least first and second cameras; (b) to track measurement points from each of the at least first and second cameras for the sequence of imaging times; and (c) to compute the physical object-space coordinates of each measurement point from the image-plane coordinates and the camera calibration coefficients for the at least first and second cameras, to thereby estimate recession of the ablating surface.