Phase error evaluation technique based on Fourier transform for refractive index detection limit of microfluidic differential refractometer

A novel phase error evaluation technique based on Fourier Transform Method is presented to estimate the phase error resolution from the spatial interference pattern. The highest phase error resolution is 3.4 × 10−8 × 2 π rad3.4 × 10−8 × 2 π rad in simulation. The simulation has shown the validity of the proposed technique compared to the result in real experiment. The influence of bit depth, size of the pixel and the spatial period of the interference fringe on the phase error resolution is also discussed in detail. The results are helpful for choosing the suitable parameters of CCD camera and controlling the whole size of the integrated microfluidic differential refractometer.