Research On New Measurement Method Of Transfer Function Of Interferometer System

The small scale manufacturing errors in middle frequency range of optical elements used in high-power solid-state laser will seriously affect the performance of the entire optical system. At present, the middle frequency errors are mainly measured by an interferometer the performance of which is evaluated by its transfer function. The methods available for measuring the interferometer system transfer function (ITF) are mainly based on standard phase step comparison method, which requires phase step with high accuracy.In this thesis, first, the concepts and testing principles of ITF are described briefly, based on which the experimental procedure of ITF by using standard phase step comparison method were proposed, the software was written and the ITF of different types of interferometer are measured. In addition, the effects of the measurement errors caused by different MASK sizes%defocus and distance of the interference cavity on the ITF were analyzed.Sencond, two new methods were proposed to measure ITF-coating step method and fringe method. The coating step method was based on the phase step comparison method with creative use of coating method to make high-precision coating step plate, removing the need of producing step plate; In fringe method, the frequency was changed by adjusting the number of fringes, and the normalized transfer function value was measured at different frequencies by the ratio of modulation. Fringe method does not require the preparation of step artifact, which greatly reduces the test cost, and is of great significance to the ITF measurement of large aperture interferometer. The data measured with both methods had less than 5% disagreement with the ones obtained with the traditional phase step comparison method, confirming the feasibility of proposed methods.Finally, due to the optical elements in strong laser optical systems with large volume, measurements of ITF of large scale interferometer has become front research topics today. The ITF of 600mm aperture interferometer were measured by using both isoplanatic region method and approximated form of fringe method. The results are of great reference value in measuring ITF of big scale interferometer.