Synthetic-Aperture Ladar (Ⅱ): Spatial Phase Biased Telescope for Transmitting Antenna

Liren, 刘立人 Liu

doi:10.3788/aos20082806.1197

Cited by 3 publications

(3 citation statements)

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“…The three target points of simulation are shown in Fig.2: the coordinates of the points in the target plane are (5,5), (0, 0), (-5, -5), and the coordinates in the vertical plane are (3.535, 5, 3.535), (0, 0, 0), (-3.535, -5, -3.535). The delay times of the points are 0.158μs, 0.156μs, 0.154μs.…”

Section: Simulationmentioning

confidence: 99%

Compensating algorithm of nonlinear phase errors using scan filter in SAIL

Liu

Lü

2009

SPIE Proceedings

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The phase errors due to the nonlinear chirp of tunable laser reduce the range resolution in synthetic aperture imaging ladar(SAIL). The compensating algorithms establishing matched and nonmatched reference paths were developed, and the phase errors were compensated in the whole echo pulse. In this paper a compensating algorithm by scan filtering is proposed. Compared to the compensation in the whole echo pulse, this compensating algorithm promotes precision and range resolution.Every echo pulse includes different echo components from all target points in footprint. The heterodyne signals of these different echoes are scan filtered from the heterodyne signal of one whole echo pulse in the spectrum. The phase errors of these heterodyne signals are measured by phase shifting algorithm in nonmatched reference path and compensated separately. Then the compensated signals are combined into whole heterodyne pulse and compressed in range. After all echo pulses are compressed in range the azimuth compensation and compression is followed.The mathematical flow of this algorithm is established. The simulation of the airborne SAIL model validates the feasibility, and the BW of range compression decreases obviously. The effects of width of the scan filter and nonlinear chirp are discussed. The conclusion of adequate width of the scan filter is given finally.

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Section: Simulationmentioning

confidence: 99%

Compensating algorithm of nonlinear phase errors using scan filter in SAIL

Liu

Lü

2009

SPIE Proceedings

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“…Pro. Liren Liu analyzed the optical characters of SAIL in space domain, and redefined the imaging azimuth and range resolutions in terms of the idea of optical imaging by a lens [6][7][8][9][10][11][12] . Directed by these analyses, we designed a multi-purpose SAIL demonstrator based on free-space optics to experimentally investigate and theoretically analyze the beam diffraction properties, antenna function, imaging resolution and signal processing algorithm of SAIL, besides, a laboratory-scaled SAIL system were built to verify the principle of design, and a primary experimental results were given [13] .…”

Section: Introductionmentioning

confidence: 99%

A synthetic aperture imaging ladar demonstrator with Ø300mm antenna and changeable footprint

et al. 2010

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A demonstrator of synthetic aperture imaging ladar (SAIL) is constructed with the maximum aperture Ø300mm of antenna telescope. This demonstrator can be set with a rectangular aperture to produce a rectangular footprint suitable for scanning format with a high resolution and a wide strip. Particularly, the demonstrator is designed not only for the farfield application but also for the verifying and testing in the near-field in the laboratory space. And a 90 degree optical hybrid is used to mitigate the external phase errors caused by turbulence and vibration along line of sight direction and the internal phase errors caused by local fiber delay line. This paper gives the details of the systematic design, and the progresses of the experiment at a target distance around 130m.

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“…Liren Liu analyzed the optical characters of SAIL in space domain, and redefined the imaging azimuth and range resolutions in terms of the idea of optical imaging by a lens. [5][6][7][8][9][10] In this research, a synthetic aperture imaging ladar (SAIL) demonstrator is designed and being fabricated to experimentally investigate and theoretically analyze the beam diffraction properties, antenna function, imaging resolution and signal processing algorithm of SAIL. Such a multi-purpose SAIL demonstrator has the following design features: (1) A unified structure of telescope antenna has a big telescope of φ300mm aperture followed by a circulated duplex of a tunable secondary telescope to transmit an illuminating wavefront of needed spatial quadratic phase and of a defocused 4-f receiver to compensate the wavefront aberration of echo for a correct and efficient heterodyne detection, thus by tuning the secondary telescope not only the far-filed but also the near-field diffraction can be physically realized.…”

Section: Introductionmentioning

confidence: 99%

A multi-purpose SAIL demonstrator design and its principle experimental verification

Zhou

Yan

et al. 2009

SPIE Proceedings

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A fully 2-D synthetic aperture imaging ladar (SAIL) demonstrator is designed and being fabricated to experimentally investigate and theoretically analyze the beam diffraction properties, antenna function, imaging resolution and signal processing algorithm of SAIL. The design details of the multi-purpose SAIL demonstrator are given and, as the first phase, a laboratory-scaled SAIL system based on bulk optical elements has been built to verify the principle of design, which is similar in construction to the demonstrator but without the major antenna telescope. The system has the aperture diameter of about 1mm and the target distance of 3.2m.

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Synthetic-Aperture Ladar (Ⅱ): Spatial Phase Biased Telescope for Transmitting Antenna

Cited by 3 publications

References 0 publications

Compensating algorithm of nonlinear phase errors using scan filter in SAIL

Compensating algorithm of nonlinear phase errors using scan filter in SAIL

A synthetic aperture imaging ladar demonstrator with Ø300mm antenna and changeable footprint

A multi-purpose SAIL demonstrator design and its principle experimental verification

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