Patent ID: 7852489
Filing Date: 2010-12-14
Classification: G01B

Abstract:
1. A surface profile measuring method for emitting a monochromatic light-beam outputted from a monochromatic light source onto a target plane and a reference plane through a dividing means to obtain a surface height and a surface profile of the target plane based on intensity value data of an interference fringe generated from the reflected light-beams which are reflected from both the target plane and the reference plane and, then, return on a single optical path, the surface profile measuring method comprising: a first step of acquiring an image of the interference fringe generated in a state that the reference plane is arranged in a posture obliquely tilted at an angle relative to a traveling direction of the light-beam; a second step of obtaining the intensity value data of the interference fringe in the acquired image for each pixel; a third step of obtaining a phase of each pixel by a model equation expressing an interference fringe waveform, where intensity value data contain that of each pixel and those of plural pixels in the vicinity of the relevant pixel, on assumption that DC components, AC amplitudes and phases of the interference fringe waveforms are respectively constant in the vicinity of the relevant pixel; a fourth step of obtaining the surface height of the target plane from the obtained phase of each pixel; and a fifth step of obtaining the surface profile from the obtained surface height of the target plane; wherein the phase is obtained in such a manner that the intensity value data g(x) of each pixel is fitted to an equation, g(x)=a +b cos {2πfx+Φ(x)}, which is the model equation of the interference fringe waveform, in the vicinity of the relevant pixel.