The Study Of Imaging Quality And Resolution Of CCD Space Camera Base On Model Experiment And Computer Emulation

The CCD space remote sensing camera imaging is different from traditional film imaging. The grain dimension of photosensitive emulsion is so small compare with the blurs of optical system that it can be ignored. But the CCD pixel dimension is a few times of the blurs of optical system. If the optical system with CCD sensor is regarded as a spatially invariant linear system, the convolution of point spread function and the object image results in error on theory.Since CCD sensor imaging is digital imaging, in this article, the image quality and resolution of the CCD sensor imaging is simulated and analyzed. Some resolutions are gotten.1. When the target is motionless, CCD sensor imaging is simulated. The pattern of the object is the resolution target-white and black strips. The relation of tthe CCD sensor imaging resolution and the MTF is gotten. When the MTF of space remote sensing camera is higher and the contrast of object is higher, it can be believed that the resolution of CCD sensor imaging is 1.6 times of the pixel dimension, in the mean while the MTF decreases 32%. It is appropriate commonly that the resolution of CCD sensor imaging is 1.8 times of the pixel dimension, in the mean while the MTF decreases 11%, because the MTF is bigger, the other parts are easier to be made and the image shows the characterization of the object well.2. In order to study usefully, both the image motion and the sampling discrete are simulated and the result shows that when the width of target strip is a constant(2a), the increasing amount of image motion is linear relation to the MTF decreased amount. When the MTF is a constant, with the increasing amount of image motion, increasing trend of the width of target strip is weakening. The numerical value is: the image motion is a/3, a/2, a, the corresponding width of target strip is 2a, 2.11a, 2.44a. The MTF is affected more badly then the resolution of the CCD sensor imaging.3. Under the the image motion and the sampling discrete conditions, the other more important result is: under the condition of engineering practice, the orientation between the target strip and the pixel row is parallel or not, the difference amount ofMTF is smaller then 1%, therefore in the engineering, the MTF of the orientation parallel can instead of the MTF of the corresponding case. Under the condition of space moving changed system and the engineering practice, A function of the pixel dimension, the MTF of CCD sensor imaging, the width of target strip and the imagemotion has been acquired4. Under the condition of one pixel image motion and the Nyquist frequencies, adopting the convolution method, the ratios of the MTF with image motion to the idea MTF are 0.667. Under the condition of one pixel image motion, adopting the modulation method, the ratios of the MTF with image motion to the idea MTF are 0.591. The difference amount of MTF is shown.They are analyzed that the types of optic system, obstructive ratio influence the MTF and the methods improvement the imaging resolution of remote sensing camera.