Optical Satellite Circular Scanning Imaging Method
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Solution Overview
Problem
Low-orbit small satellites face challenges in achieving meter-level resolution with thousands of kilometers of imaging coverage width due to limitations in area-array camera field of view and increased size, weight, and power consumption when using multiple CCDs or camera combinations.
Innovation Solution
The method involves calculating specific angles and rotation speeds for an area-array camera on an optical satellite to perform ultra-wide circular scanning, ensuring seamless imaging coverage by rotating the satellite around the earth-pointed axis and adjusting the camera's field of view to achieve a spiral strip imaging pattern without gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple CCDs or area-array cameras are spliced or combined to increase imaging coverage, then the image coverage is improved, but the size, weight and power consumption of the satellite greatly increase
Solution Approach 1:
The patent merges the functions of multiple CCDs or area-array cameras into a single detector by implementing a circular scanning mechanism. The detector rotates to sweep across a wide angular range, combining the imaging capability of one detector over time to achieve the same coverage that would otherwise require multiple detectors simultaneously, thereby reducing satellite weight.
Solution Approach 2:
The patent introduces dynamic rotation of the satellite or detector to enable a single detector to cover a wide area. By rotating the detector in a circular scanning pattern, the system dynamically expands the imaging coverage beyond the static field of view of a single detector, achieving large-area coverage without adding multiple heavy components.
2Area of stationary object
If the side swing capability of the area-array camera is increased to expand imaging area, then the imaged area is improved, but the image coverage cannot be increased
Solution Approach 1:
The patent transitions from two-dimensional side swing motion to three-dimensional circular scanning motion. By rotating the detector around the satellite's flight path in a circular pattern, the system adds a temporal dimension to the imaging process, allowing a single detector to cover a much larger area over time while maintaining adaptability for different coverage requirements.
3Measurement precision
If the field of view of the optical camera is fixed, then the imaging resolution is improved, but the imaging width is limited
Solution Approach 1:
The patent implements continuous circular scanning motion to bridge the gap between fixed field of view and wide imaging width. The detector continuously rotates to sweep across the ground, maintaining high resolution during exposure while accumulating wide-area coverage over the scanning period, thereby achieving both high resolution and wide imaging width.
Data Source
AI summary
A technology for ultra-wide circular scanning imaging by an optical satellite is provided. Calculating an angle θ1 between the outermost field of view of an area array camera (2) and an earth-pointed axis (q) of a satellite (1) according to the width W required for ground imaging coverage in a direction perpendicular to the flight direction (b) of the satellite (1) and according to the height h of the orbit of the satellite (1); installing the area array camera (2) on a side surface of the satellite (1) according to the angle θ1; calculating the maximum rotation angle ωmax allowed by the satellite (1) according to the minimum exposure time T of a detector of the satellite (1) and the worst ground pixel resolution r of the satellite (1); selecting a rotation speed ω of the satellite (1) that is less than ωmax, and setting the rotation speed ω to be the rotation speed relative to the ground.