System and method of measuring surface topography

The surface topography measuring system, for measuring a surface topography on an object surface, comprising:

• a light source for providing a test beam;
• a reflecting mirror selectively moving to different positions on a first axis;
• a beam splitter for dividing the test beam into a first sub-beam, entering the reflecting mirror along a first axis, and a second sub-beam, entering the object surface along a second axis;
• a photographing device for receiving the first sub-beam reflected from the reflecting mirror on the first axis, and receiving the second sub-beam reflected from the object surface to generate N images, the first sub-beam reflected from different positions of the reflecting mirror being defined as N reflected beams, and the second sub-beam reflected from the object surface being defined as an object reflected beam, and the N images related to the N reflected beams and the object reflected beam, and each of the N images having a plurality of interference fringes;
• and
• a processing device, electrically connected to the photographing device, for analyzing the interference fringes in each of the N images to calculate N curve formulas, and calculating the surface topography of the object surface from the N curve formulas;
• wherein a first angle is between a first normal line of the reflecting mirror and the first axis, or between a second normal line of the object surface and the second axis, N is a positive integer greater than 2.