Patent attributes
This three-dimensional shape measurement method comprises: a projection step for projecting an interference fringe pattern (F) having a single spatial frequency (fi) onto an object surface; a recording step for recording the pattern (F) as a digital hologram; and a measurement step for generating a plurality of reconstructed images having different focal distances from the hologram, and deriving the distance to each point on the object surface by applying a focusing method to the pattern (F) on each of the reconstructed images. The measurement step extracts the component of the single spatial frequency (fi) corresponding to the pattern (F) from each of the reconstructed images by spatial frequency filtering, upon applying the focusing method, and makes it possible to achieve a highly accurate measurement in which the adverse effect of speckles is reduced and the advantage of a free-focus image reconstruction with holography is used effectively.
