Nonlinearity In Heterodyne Interferometer Research Articles

The effect of laser source and PBS on the nonlinearity in heterodyne interferometer

The nonlinearity of heterodyne interferometers is caused not only by polarization ellipticity or nonorthogonality of the laser beams. The imperfect optical parts, especially the polarizing beam splitter (PBS), can also contribute. Past researchers pointed out that the nonlinearity error due to the leakage of the PBS could be generally neglected. Because the laser beam has to pass the PBS at least two times and its leakage component is mostly filtered before being mixed at the receiver. This paper has proved this viewpoint experimentally. It also shown how to distinguish and measure the nonlinearity errors caused by the two reasons experimentally.

Research on Phase Compensation of Nonlinearity Error in Heterodyne Interferometer

A novel method to eliminate nonlinearity error in heterodyne interferometer is studied in the paper. A simple phase compensation system is built and the nonlinearity error is eliminated by rotating the polarizer in front of the optical detector in interferometer according to phase difference signal. The experiments demonstrate that the method is available to eliminate one-order or high-order nonlinearity in heterodyne interferometer. The effects to decrease nonlinearity error depend on high measuring precision of phase difference and high control precision of the rotating polarizer.

Research on Compensation of Nonlinearity in Heterodyne Interferometer

The demands of nano-measurement and nano-positioning now in research and industries become the challenge for heterodyne interferometer because its nonlinearity often limits the effective resolution. This paper introduces new developed method for compensation of the nonlinearity in heterodyne interferometer and explains what accuracy can be reached with demonstrations figured by the test results. On the basis of theoretical analyses and experimental investigations it shows which exactness can be expected.

Eliminate of the Nonlinearity in Heterodyne Interferometer

A new approach is found to eliminate the nonlinearity of heterodyne interferometer. It uses a simple phase compensation system by rotating a polarizer which is set up before the detector in the interferometer. This method can be used in most science researches and the industry precision nanometer measurement, and it is valid for all nonlinearity errors whether it is a first-order or a higher-order error, or caused by any reasons.

Optical parts and the nonlinearity in heterodyne interferometers

The nonlinearity of heterodyne interferometers is caused not only by polarization ellipticity or nonorthogonality of the laser beams. The imperfect optical parts can also contribute. Our experiments show that the nonlinearity of heterodyne interferometers can be serious even when perfect optical parts are used. Also it will be shown how to examine and distinguish between the errors experimentally. Moreover, an interesting approach was found to decrease the nonlinearity for heterodyne interferometers.