Integral time calculation method for pushbroom off-axis remote sensing camera based on equivalent focal plane

Abstract

The invention provides a high-precision integral time calculation method for a pushbroom off-axis remote sensing camera based on an equivalent focal plane. A certain included angle exists between a focal plane of the pushbroom off-axis remote sensing camera and a sub-satellite point horizontal plane. According to a current pushbroom off-axis remote sensing camera, an off-axis angle exists between a ray axis and an optical axis, the camera needs to pitch by a certain angle in order to make the optical axis perform imaging on sub-satellite points, consequently, a certain included angle exists between the focal plane and the sub-satellite point horizontal plane, and integral time calculation is not accurate. In order to solve the problem, the equivalent focal plane parallel to the sub-satellite point horizontal plane is constructed, a rigorous geometrical relation is established, a real pixel size corresponding to charge transfer time is solved, and therefore accurate integral time is obtained. Through the method, integral time calculation precision can be effectively improved, and an effective means is provided for improving satellite in-orbit imaging quality.

Description

technical field [0001] The invention relates to an integration time calculation method of a push-broom off-axis remote sensing camera based on an equivalent focal plane, and belongs to the technical field of satellite on-orbit imaging quality. Background technique [0002] At present, with the rapid development of earth observation and remote sensing satellites, the imaging performance of the camera directly determines the overall performance of the satellite and the final image quality. Due to the inevitable existence of central occlusion in the axisymmetric reflective optical system, the existence of central occlusion will not only lose the luminous flux, but also reduce the diffraction-limited MTF value of the system at medium and low frequencies. In order to solve the central occlusion problem of the axisymmetric reflective optical system, researchers have proposed an off-axis reflective optical system, by increasing the off-axis aperture of the axisymmetric system, incr...

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Problems solved by technology

[0003] The off-axis reflection system eliminates the central occlusion by properly tilting and eccentric the mirror surface, but there is a certain angle (off-axis angle) between the actual visual axis and the optical axis, so the satellite imaging model is shown in Figure 1(b). The boresight of the actual imaging is far away from the sub-satellite point, which affects the imaging quality; in order to make the boresight of the current off-axis optical remote sensing satellite image the sub-satellite point as much as possible, the camera is usually pitched at an angle as a whole, as shown in Figure 1(c) As shown, at this time, there will be a certain angle between the focal plane and the horizontal plane of the sub-satellite point. The traditional integration time calculation method will not be able to obtain an accurate integration time due to the change in the pixel size of the focal plane corresponding to the actual charge transfer time.

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