Though the demand for measuring discontinuous object is increasing, it is difficult problem to solve it. The conventional methods to measure surface profile have weak point on them. An optical triangulation technique is less accurate than other method relatively. Conventional interferometry and Moire method cannot measure discontinuous object due to 2π ambiguity problem. These brings out the necessity of Wavelength Scanning Interferometry(WSI) research. WSI is based on Twyman Green Interferometry. The light emitted by the laser, which is possible to scan the wavelength, is led to Twyman Green interferometry. Generally, the relation between the phase of interference fringe, φ, detected by CCD camera and the wavelength,λ is φ=2πL/λ where L is the optical path difference (OPD) between two corresponding points of the reference mirror and the object surface. Appling the wavelength scanning technique to this interferometry, the phase variation due to the wavelength difference is given as the following equation, Δφ=2πL Δλ/$λ^2$ where Δλ is the wavelength difference and Δφ is the phase variation of the interference fringe measured by CCD camera. With the Δφ measured, we can calculate the OPD distribution L(x, y) on the object surface with respect to the reference mirror, and then the height distribution h(x, y) of the object surface can be obtained without difficulty, since h(x, y) = L(x, y)/2. To measure the phase variation, Fourier Transform method and zero crossing algorithm is used conventionally. However, these method have maximum 2π error during measure phase variation, therefore they have height measurement error. So, it is necessary to make new phase measurement algorithm. In this thesis, the sine curve fitting algorithm to improve the measurement capability is proposed. The experimental results to prove proposed method are shown.
