Generally camera consists of optical system and detection system (CCD or CMOS). Camera field represents the scope of images of shooting device and is an important indicator of camera.
Currently, camera field calibration methods can be classified into the method through angular field and through linear field by the difference in definition method: (1) Angular field means the angle range in which camera can carry out imaging and receiving. The test method is: fixing camera’s mounting face and turntable’s plane together and making camera optical imaging system’s object node coincide with spindle center and align with the parallel light tube, and making the star hole on the focal plane of the parallel light tube imaged in camera’s imaging and receiving system; turning the turntable to make star hole image move to the other side from one side of camera-shot picture. The angle that the turntable turns around is the camera’s field angle 2w. As the camera imaging and receiving system’s CCD or COMS is rectangular generally, it is needed to repeat the above-mentioned process after determining the field angle in a direction and after rotating by 90° and then determine the field angle in another direction. The method needs to have the clear aperture of the parallel light tube covering camera’s entrance pupil all the time during turning the turntable. As camera has only one mounting face, test in another direction is difficult. Turntable and parallel light tube are expensive generally, so the method is poor economically. (2) Linear field means the width that camera can carry out imaging and receiving with the camera horizontally mounted and within certain shooting distance. The test method is: measuring the horizontal-direction field width H vertical to the optical axis direction at the Point L as a camera optical imaging system node and in the optical axis direction, to serve as camera’s horizontal linear field. Vertical-direction linear field can be determined by the width-height ratio of the imaging picture of camera imaging component’s target surface.
In order to solve the above-mentioned problems in background technology, Li Kun, Chen Yongquan and Zhao Jianke, etc. with the Test Center of XIOPM invented a camera field calibration method and device able to improve test precision, with the strong points of: (1) Avoiding the errors due to inaccurate positioning of camera node location and improving test precision and repeatability by determining the horizontal field under different shooting distances and the interval between different shooting distances; (2) It is able to carry out camera field measurement by the similarity of camera geometric relationship under different imaging distances and using the target plate and translation stage and and is better economically; (3) Compared with the linear field determination method under traditional single imaging distance, it is able to make the object target plate center imaged at the center of the camera-shot picture by adjusting camera posture, which makes camera move in the direction along the visual axis, improves test operability and lifts test precision.
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