In Orbit Detection Of Wide-field Wavefront Error Of Space-based Optical Remote Sensor

In recent years, with the development of high-resolution space-based optical remotesensing, the aperture of the remote sensor is becoming larger and larger. Because of thelong focal length, the light weight, being foldable and the special environment of space, theimage quality of the remote sensor is affected by a variety of potential factors, resulting inlower image resolution. To solve this problem, there are two approaches. One way, we canuse complex adaptive optics technology, the other way,we can only use the wavefrontsensing technology of adaptive optics to detect the pupil wavefront in orbit, and thenrestore the images offline.The field of view of the space camera is usually so wide that different fields havedifferent aberrations. In order to measure the aberrations of each field of the space cameraaccurately, several wavefront sensors is needed to be arranged in the whole fields. On theother hand, in order to reduce the complexity and cost of the system, the number ofwavefront sensors should be as less as possible.For different optical systems, the aberrations vary with the field of view in differentways, so the arrangement of the wavefront sensors should be based on its variationcharacteristics. For a co-axial three-mirror line-scan space camera, we try to arrange threewavefront sensors, one in the central field and the others in the two marginal fields.According to the wavefront error detection of three fields, we estimate the wavefront errorof all the fields by data fitting. For a co-axial three-mirror space camera with area imagedetectors, we try to arrange five wavefront sensors, one in the central field and four in themarginal fields. According to the wavefront error detection of the five fields, we canestimate the wavefront errors of all the fields by data fitting. This dissertation studied thefeasibility and accuracy of these two methods by simulation.In simulation,the co-axial three-mirror optical system is modeled in Zemax.Thesurface error of the primary mirror, position error of the secondary mirror, surface error ofthe secondary mirror and surface error of the tertiary mirror is introduced through thedynamic data exchange (DDE) between Matlab and Zemax. The wavefront error of eachfield is also read out through the DDE channel and then analyzed in Matlab. The simulation results show that for in-orbit wavefront sensing of wide-field line-scanspace camera with a co-axial three-mirror system, the wavefront errors of all fields of viewcan be estimated using only three wavefront sensors,with a preknowledge of the originaldesign errors. Considering fitting error only, the absolute error is in the order of10-5and therelative error is less than5%. For in-orbit wavefront sensing of wide-field space camerawith area image detectors, five wavefront sensors are needed to estimate the wavefronterrors of all fields of view with a preknowledge of original design errors. Consideringfitting error only, the absolute error is in the order of10-4and the relative error is less than5%. Some Zernike coefficients are smaller than others, and the relative estimated error willbe large, but it has little contribution to the total error. This study provides a feasible wayfor in-orbit wavefront sensing of wide-field line-scan and area image space cameras.