研究目的
To demonstrate the feasibility of achieving high azimuth resolution focused images within short coherent integration time using ISAL technique and present outdoor ISAL experiment system along with well-focused high-resolution images.
研究成果
The ISAL technique has demonstrated the feasibility of achieving high azimuth resolution focused images within short coherent integration time. The outdoor ISAL experiment system and some well-focused high-resolution images are presented with the digital signal processing algorithm.
研究不足
ISAL is more sensitive to phase errors caused by many factors which the microwave radar can ignore, such as ladar vibration, atmospheric turbulence, moving target jitter, etc.
1:Experimental Design and Method Selection:
The experiment utilizes the inverse synthetic aperture technique and coherent laser radar to obtain high resolution two-dimensional images. A modified phased gradient autofocus algorithm (MPGA) is used to suppress errors and improve image quality.
2:Sample Selection and Data Sources:
The targets were constructed by retro-reflective material with five floor bracket, fixed in a translational rotating platform.
3:List of Experimental Equipment and Materials:
The setup includes a laser source, beam splitter, RF amplifier, electro-optic phase modulator, optical amplifier, circulator, fiber alignment, beam expander, balanced detector, and a translational rotating platform.
4:Experimental Procedures and Operational Workflow:
The ISAL transmits wideband coherent laser created by modulating a phase coded signal onto a continuous laser waveform at 1550nm, and detects weak echoes reflected from moving targets by a coherent detection system.
5:Data Analysis Methods:
The modified phase gradient autofocus technique is used to estimate and remove the pulse-to-pulse phase errors.
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