Patent ID: 8385629

Claim:
A method for acquiring phase information comprising the steps of: obtaining a deformed fringe image related to a first phase information with respect to a first surface shape information of an object; acquiring a first frequency spectrum image with respect to the deformed fringe image, wherein the first frequency spectrum image has a first frequency spectrum area corresponding to the first phase information with respect to the first surface shape information of the object and having a first primary spectrum region and a first secondary spectrum region distributed extending from two sides of the first primary spectrum region respectively toward the sides of the first frequency spectrum image; extracting a first spectrum information from the first primary spectrum region and the first secondary spectrum region by employing an oval-shaped filter shaped to cover the first primary and the first secondary spectrum regions, wherein a length of a long axis of the oval-shaped filter is half of an image length of the first frequency spectrum image measured along a first direction; and obtaining the first phase information by performing a calculation upon the first spectrum information.