Three-dimensional shape measuring method, three-dimensional shape measuring apparatus, and focus adjusting method

摘要

An operation of projecting slit light onto an object to be measured and receiving light reflected thereon, and an operation of acquiring a two-dimensional image concerning the object to be measured are repeated a certain number of times by changing a focal length. An imaging contrast is calculated with respect to each of areas on the two-dimensional images acquired at the different focal lengths. A high contrast area where the imaging contrast exceeds a predetermined threshold value is extracted with respect to each of the two-dimensional images acquired at the different focal lengths. Distance information concerning the respective areas is acquired by performing triangulation with respect to each of the high contrast areas. Position adjustment of measurement dimensions is performed in such a manner that the areas are included in the measurement dimensions having the predetermined measurement depth, based on the distance information.