The application of improved Fourier transform profilometry

3-D object shape can be profiled by using optical noncontact measurement methods, such as improved Fourier transform profilometry, etc. These methods restore the object shape through analyzing the continuous phase distribution of an optical structured field that is modulated by the shape. However, in practice, many shapes to be measured have steep height variation and may cause shadows in the modulated phase distribution. Such kind of object shape can not be restored. We propose a method to solve this problem. With this method, the improved Fourier transform profilometry can be used in many areas. This paper describes the theory.