An Automatic Focusing System of Astronomical Telescope Based on Image Definition Evaluation

The automatic focussing(AF)applied in astronomical telescope is helpful for enhancing automatization and efficiency, improving focusing precision and quality, avoiding dependency on the experience of operator. Due to the image of an object's having less detail than scenery, those arithmetics used in camera AF system are not suitable for astronomical telescope AF system. A new evaluation function of image definition which is suitable for object is proposed in the paper.