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This study examines the imaging problems in airborne synthetic aperture ladar with single detector and dual detectors along tracks under platform vibration condition. Because platform vibrations affect imaging processing for short intervals negligibly, a method uniting the subaperture imaging and phase gradient autofocus is considered for single-detector ladar. To obtain long stripmap images in azimuth, the stripmap phase gradient autofocus method and the subaperture image mosaic process using Doppler centroid estimation are used. Their performance is analyzed and compared. Considering the shortage of single-detector ladar, a method based on along-track dual-detector interferometric processing is proposed to estimate and compensate for the vibration phase error. The simulation verifies the effectiveness of the proposed methods.

In this study, the performance of three phase-modulated signals used in airborne Synthetic Aperture Ladar (SAL) is investigated. The transmitting and receiving modes and imaging processing methods for these signals are studied. Considering that the swath of the airborne SAL is very narrow, in order to reduce the AD sampling rate of the wideband signal, a “phase-dechirping” receiving mode is proposed for the phase-modulated signal based on the Linear Frequency Modulation (LFM) signal. The imaging simulation results for these three phase-modulated signals validate the effectiveness of the proposed method.

The current status and the domestic research problems of air-borne Synthetic Aperture Ladar (SAL) are introduced and key technologies are analyzed. Based on a principle prototype, the system implementation scheme with a combination of SAR electronics technology and optical technology is given. The future practical system metrics and technological approaches are analyzed. Besides, application direction of Synthetic Aperture Ladar is clarified.