Synthetic-aperture imaging laser radar: laboratory demonstration and signal processing

Area of Science:

• Optics and Photonics
• Remote Sensing
• Signal Processing

Background:

• Conventional imaging laser radar systems are limited by the diffraction limit of telescope apertures, restricting spatial resolution.
• Achieving fine-resolution, long-range imaging typically requires large and complex optical systems.

Purpose of the Study:

• To investigate synthetic-aperture imaging laser radar (SAIL) as a method to overcome the diffraction limit.
• To demonstrate the capability of SAIL for high-resolution, long-range 2D imaging using modest aperture sizes.
• To present the first optical synthetic-aperture image of a fixed, diffusely scattering target with a moving aperture.

Main Methods:

• Development and testing of a laboratory-scale SAIL testbed.
• Implementation of digital signal-processing techniques for aperture synthesis and image reconstruction.
• Acquisition of optical synthetic-aperture images for both retroreflecting and diffuse scattering targets.

Main Results:

• Demonstration of fine-resolution, well-focused SAIL images, surpassing the diffraction limit of conventional systems.
• Successful acquisition of the first reported optical synthetic-aperture image of a diffusely scattering target with a moving aperture.
• Comparison showing enhanced resolution achieved with synthetic-aperture imaging versus real-aperture imaging.

Conclusions:

• SAIL is a viable technique for achieving fine-resolution, long-range 2D imaging with modest apertures.
• The developed digital signal-processing algorithms and hardware elements address laser waveform instability, crucial for robust imaging systems.
• This research represents a significant advancement towards practical and robust synthetic-aperture imaging laser radar systems.