An accurate simulation algorithm for focus variation microscopy

The focus variation microscopy is widely used and researched in both industrial and academic field. But the 3D construction quality of surface topography is affected by the noise, the double peak value, and the discontinuous surface, and so on. A simulation method for focus variation is proposed based on the physical model of optical imaging and the Point Spread Model(PSF). At first, the linear relationship between the blur factor sigma of Gaussian function and the defocus distance delta is deduced which is called point spread parameter lambda, then, considering the positive correlation between blur factor sigma and blur degree, the difference between the real defocused image and the calculated image by Gaussian convolution operation to real captured focused image is shown. It is used to the objective to computed the accurate value sigma and the spread parameter lambda. At last, the difference between focus measure valued of real image sequence and simulation image sequence is used to verify the method. The simulation method is a judgement basis for focus measurement, the single peak of focus curve, and the identification of high-frequency noise.