The Study Of The System Error Correction Method Of The Subaperture Stitching

In large size optical element surface of each subaperture stitching measurement, using digital wavefront interferometer for measurement is relative, therefore a reference flat error will inevitably enter the test data, and as the system error makes stitching error greatly increased. The system error can not use the existing stitching error averaging algorithm to solve, must use additional tests to calibration and correction. For this, this paper made the following studies:(1)In-depth analysis of sub aperture stitching in the presence of various errors, because the single sub aperture measurement and the introduction of standard flat error as the system error in the splicing process will be amplified, calculated its magnification, in its analysis of the different pore size distribution on measuring accuracy influence.(2)On the three surface of mutual check method principle, preparation of practical calculation program, established a security three mutual check the validity of the results to obtain a basic method of planar feature section. Zernike low order polynomial can construct the system error correction of wavefront by using of three mutual the flat in the splicing axis direction of the2D data.Through the Matlab algorithm simulation, validation of the finite target wavefront correction method of system error correction of sub-apertures stitching effectiveness.(3)In the actual development of the sub aperture plane interferometer(7×7), using Matlab and C++mixed programming and the design of data processing software, the actual completion of the interferometer reference flat system error correction wave acquisition and real time correction.The experiment proves that this method can be applied to the sub-aperture stitching measurement and other surface test, and more effectively reduce reference flat surface shape error caused by the effects of systematic errors, improving the precision of sub aperture stitching wavefront. Use of the low order correction of wavefront fitting not only can enhance the robustness of the whole system, so that only the outside temperature sensitive, but also has very important significance in large size optical element surface stitching measurement.