Synthetic aperture laser radar imaging method, instrument and system

Abstract

The invention provides a synthetic aperture laser radar imaging method, instrument and system. The method comprises the following steps of transmitting a laser signal through an optical telescope arranged on a synthetic aperture laser radar, and simultaneously receiving echo signals by adopting at least two optical telescopes arranged on the synthetic aperture laser radar along an azimuth direction; carrying out along track interferometry processing on the echo signals to obtain an along track differential interferometry phase; acquiring a slope distance direction speed error through the alongtrack differential interferometry phase, and acquiring a motion error caused by vibration by utilizing the slope distance direction speed error; respectively carrying out motion error compensation processing on the echo signals received by the at least two optical telescopes by utilizing the motion error in order to obtain at least two pieces of azimuth direction to-be-compressed data; and carrying out Doppler signal coherent combination on the azimuth direction to-be-compressed data to complete azimuth compression processing of imaging.

Description

technical field [0001] The invention relates to a synthetic aperture laser radar imaging method, instrument and system. Background technique [0002] Synthetic Aperture Lidar (SAL) combines synthetic aperture technology and coherent laser detection technology, and has a series of technical characteristics such as large Doppler frequency shift, high pointing accuracy, high ranging accuracy, and short synthetic aperture time. Synthetic aperture lidar solves the technical bottlenecks of LiDAR system grid density, imaging resolution and detection energy. Realize a brand-new synthetic aperture radar system based on optical band, break through the diffraction limit of geometric optics, and greatly improve the imaging resolution. The laser signal is convenient for large-bandwidth modulation, so it is beneficial to improve the range resolution; a small relative motion between the radar and the target can achieve a large azimuth Doppler shift, so it can achieve a high azimuth resolu...

AI Technical Summary

Problems solved by technology

However, the following two traditional motion compensation ideas are also difficult to solve the problem of sub-micron SAL motion error compensation: First, the motion compensation method based on the motion measurement sensor is realized by a high-precision positioning and orientation system (Position and Orientation System, POS) Measurement of platform vibration, motion error compensation during imaging processing

However, the position measurement accuracy of the current highest-precision POS system is on the order of centimeters, which is far from meeting the needs of SAL high-resolution imaging; secondly, the most classic method of motion estimation and compensation based on radar echo data is the phase gradient self-focusing algorithm

This method relies on the existence of certain strong scattering points in the current area, and it will be difficult to achieve image focus for uniform scenes without ideal point targets.

And because the laser wavelength is extremely short, the negligible motion error in the traditional microwave band will cause a phase error of more than 2π, and the image defocus is very serious, which brings great challenges to the phase gradient self-focusing algorithm

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