Numerical Simulation Of Imaging Systems And Research On Lucky Imaging Techniques

Because the atmospheric turbulence has a severe influence on quality of images from a ground-based optical telescope, the high resolution imaging technology becomes a research hot topic in the recent years. Lucky imaging is a high resolution imaging technique which can effectively reduce the influence of the atmospheric turbulence after an observation. As the detector noise is inevitable in the images, the lucky imaging is affected by the atmosphere and the detector status.In order to study the influences of the atmosphere and the detector status on the lucky imaging, we propose a method for numerical simulation of astronomical images based on the atmospheric random phase screen and the CCD noise characteristic in this thesis. A series of short exposure star images affected by the atmosphere and the detector noise can be generated by this simulation program. After an astronomical pre-processing, a classic lucky imaging algorithm is used to get the high resolution astronomical images. These simulation images are very close to the measured lucky images, indicating that the simulation method is correct and feasible. And then, a specific evaluation criteria based on human visual perception of grayscale image is suggested so as to discuss the resolution of digital astronomical images and a limiting separation between two component stars of the binary. Based on the binary limiting separation, the relationship between different atmospheric conditions, CCD noise (readout noise, dark current noise, photon short noise) and high resolution image is analyzed. The results show:1. the high resolution images will be obtained under the conditions of good atmosphere and low CCD noise; 2. with the atmospheric coherent length ro increasing gradually, the astronomical image quality is getting better and better; 3. as the CCD noise increases gradually, the astronomical image quality becomes worse.