A method and inspection head apparatus for optically measuring geometric dimensions of a part are provided. The method optically measures the geometric dimensions of a part having a part axis at an inspection station. The method includes directing an array of spaced planes of radiation at the part so that the part occludes each of the planes of radiation at spaced locations along the part axis to create a corresponding array of unobstructed planar portions of the planes of radiation. Each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part. The method further includes measuring the amount of radiation present in each of the unobstructed planar portions.