A Demonstrator of All-Optronic Multifunctional Down-Looking Synthetic Aperture Ladar

摘要

The design and laboratory experiment of a demonstrator of all-optronic down-looking synthetic aperture imaging ladar (SAL) is presented in this paper, in which the sensing-to-processing chain is carried out with light. The ultra-fast processing capability from image acquisition to real-time reconstruction is shown. The demonstrator consists of a down-looking SAL unit with a beam scanner and an optical processor. The down-looking SAL unit has a transmitter of two coaxial orthogonally polarized beams and a receiver of polarization-interference self-heterodyne balanced detection. The linear phase modulation and the quadratic phase history are produced by the projection of movable cylindrical lenses. Three functions of strip-map mode, spotlight mode and static mode are available. The optical processor is an astigmatic optical system, which reduces to a Fourier transform system and a free-space of the Fresnel diffraction to realize the matched filtering. A spatial light modulator is used as the input interface. The experiment is performed with an optical collimator. The system design is given, too. The down-looking SAL has the features such as a big coverage with an enhanced receiving aperture and little influence from atmospheric turbulence and the optical processor is simple.