Laser Synthetic Aperture Coherent Imaging for Micro-Rotating Objects Based on Array Detectors

Abstract

Through the relative motion of ladar and object, inverse synthetic aperture ladar can form the virtual synthetic aperture and improve the imaging resolution. On the basis of coherent array detectors with the laser local oscillator, the problem of laser synthetic aperture coherent imaging for micro-rotating objects is studied. Firstly, structure and parameters of the telescope system based on the diffractive optical system are introduced. Then, the signal model of the imaging method is built, the imaging method is proposed, and influence of noise is analyzed. Afterwards, the signal model of the vibrating object is established and the vibration phase compensation method is proposed. The imaging method proposed forms a virtual aperture through micro-rotation of the object, and realizes high-resolution imaging in the pitch direction and azimuth direction. Without transmitting or processing broadband signals, the imaging system is easy to realize in engineering, and simulation results verify the effectiveness of the imaging method. Meanwhile, Fourier ptychography in the far-field condition is analyzed, and characteristics of the two methods are compared. It is concluded that the imaging method proposed belongs to the concept of traditional matched filter coherent imaging while far-field Fourier ptychography is classified into the category of super-resolution imaging.

Keywords

• Laser synthetic aperture coherent imaging
• coherent array detectors
• laser local oscillator
• inverse synthetic aperture ladar
• diffractive optical system
• fourier ptychography