Large Aperture And Long Focal Length Image Quality Detection System

In this thesis, the principle of Talbot effect theory and moire fringe technology was studied. On the basis of Talbot effect, moire fringe technology, and scanning method, a novel method for the precise measurement for wave-front of large aperture lens was presented.When a plane wave passes through a lens and illuminates on a Ronchi grating, Talbot images will appear at periodic Talbot distance behind the grating, the period of the Talbot image of the Ronchi grating has a relationship with the long focal length of the lens. If we put another Ronchi grating at the position of the Talbot image, then moire fringe will appear, if the angle of incoming wave-front changes, the moire fringe will move significantly; according to the principle of moire fringe, the offset of moire fringe has a corresponding relationship with the angle change of incoming wave-front. By image capture system, the digital image of the moire fringe was captured and the offset of the moire fringe could be accurately calculated by computer, according to the relationship between the offset of moire fringe and the incoming wave-front, the slope of the incoming wave-front can be got; For large aperture lens, scanning method was developed to measure the slope of wave-front in different locations within the lens, by wave-front reconstruction method, the whole wave-front of the lens can be got. The feasibility of this method was analyzed; the accuracy of this method was discussed and also the factors that would affect the measurement accuracy were demonstrated.A complete set of measurement system has been developed. We have finished the feasibility analysis of this method, hardware and software design of the measurement system, including the mechanical structure designing, laser booming system designing, wave-front reconstructing and its simulation, and so on...