Surface roughness measurement by using interferometer and active interferometer stabilization

The profile of the mirror surface is measured by using optical phase shift method and Twymann-Green interferometer. Phase map is calculated by applying 4-buckets method and Vikhagen phase shift algorithm is applied to escape convolution errors. From that the obtained roughness of the mirror surface is around 20 nm, rms roughness value. Also, the interferometer was stabilized by using fringe locking method. Also, we propose two colors method very precise surface profile and the length can be measured in the harsh environmental conditions.