Inverse synthetic aperture LADAR demonstration: system structure, imaging processing, and experiment result.

Area of Science:

• Optics and Photonics
• Remote Sensing
• Signal Processing

Background:

• Long-distance imaging presents challenges in resolution and coherence.
• Inverse Synthetic Aperture LADAR (ISAL) offers a method for high-resolution remote sensing.
• Maintaining laser coherence over extended distances is critical for ISAL performance.

Purpose of the Study:

• To demonstrate a long-distance ISAL imaging experiment over 1 km for cooperative targets.
• To achieve two-dimensional high-resolution imaging with resolution exceeding 2.5 cm.
• To analyze the impact of coherent processing interval (CPI) and local oscillator (LO) time delay on laser coherence.

Main Methods:

• Utilized an electro-optic in-phase and quadrature modulator for a 6 GHz bandwidth linear frequency-modulated continuous waveform (LFMCW).
• Employed a fiber delay line to reduce the coherent processing interval (CPI), thereby lowering laser frequency stability requirements.
• Formed images using two-dimensional Fourier transform and joint time-frequency transform methods.

Main Results:

• Successfully demonstrated outdoor ISAL imaging over a distance of 1 km.
• Achieved a two-dimensional high-resolution image with resolution exceeding 2.5 cm.
• Validated the system's performance through detailed experiment results.

Conclusions:

• The developed ISAL system is effective for long-distance, high-resolution imaging of cooperative targets.
• Optimizing CPI and LO time delay is crucial for managing laser coherence in ISAL systems.
• The experimental validation confirms the system's capability and potential for remote sensing applications.