On-orbit visual principle point monitoring system of three-line array camera

Visual principle point is a key photogrammetry parameter while the position change of it can only indirectly be estimated by the inverse calculation of the ground control point presently. To get the exact position change of the visual principle point an on-orbit monitoring system of three-line array camera is proposed. The system is composed of light source part and photoelectric detecting part that move along with the lens and the line array CCD respectively. The position change of the visual principle point can be derived by the position change of the two light spots. This system will not change the structure of the camera and influence the function of it. Experimental system is built up and ground test results prove the feasibility of the monitoring system and show the accuracy of it is better than 1 μm .