Optical image processing for synthetic-aperture imaging ladar based on two-dimensional Fourier transform

Abstract

A two-dimensional (2D) Fourier transform algorithm for the image reconstruction of synthetic-aperture imaging ladar (SAIL) collected data is suggested. This algorithm consists of quadratic phase compensation in azimuth direction and 2D fast Fourier transform. Based on this algorithm and the parallel 2D Fourier transform capability of spherical lens, an optical principle scheme that processes the SAIL data is proposed. The basic principle, design equations, and necessary analysis are presented. To verify this principle scheme, an experimental optical SAIL processor setup is constructed. The imaging results of SAIL data obtained by our SAIL demonstrator are presented. The optical processor is compact, lightweight, and consumes low power. This optical processor can also provide inherent parallel and speed-of-light computing capability, and thus has potential applications in on-board and satellite-borne SAIL systems.

Compensation for the Decoherence Effect in Heterodyne Detection of Rough Targets and a Target Vibration Characteristic Measurement System

“…According to Eqs. (5), (6), and (7), Fig. 9 presents the variations in heterodyne efficiency 〈i IF (t)〉 with the root mean square δ.…”

“…In previous works, optical heterodyne technology has been applied to synthetic aperture lidar (SAL) 1,2 . Research on SAL has mainly focused on imaging technology 3,4 , phase compensation technology 5 , signal processing technology 6 , linear frequency hopping technology, and optical heterodyne detection [7][8][9] . In such applications, target information can be extracted directly from the IF signal (amplitude, frequency, or phase).…”