Testing technique for focus surface message of aerial cameras

Focus surface message includes focus of the lens and the situation of the real image plane in the focus plane range or not. Testing the focus surface message is an important prerequisite to ensure the high quality image of aerial camera. A auto-testing system of the focus surface message is proposed, and the measuring principle, constitution and the software of system are described. The focus surface message is yielded by the optical collimate system with long focus and the image is received by area CCD (Charge Coupled Device) camera. Using center of gravity method to treat data, the precision of 0.1 percent for the focus of aerial camera lens can be attained and the accuracy of 100 percent for the situation of the real image plane can be made.