Range migration (or range focusing) techniques are widely used in optical, acoustic, and microwave real-time image reconstruction methods. They have been successfully applied to far-field 3-D imaging where they rely on plane-wave assumptions, which ignore the data amplitude variation over the acquisition aperture. The accuracy of the plane-wave assumption, however, quickly degrades in close-range imaging, where amplitude variations are significant and where the range to the target is on the order of the range sampling step. Here, we present a range-focusing method of improved accuracy, which is applicable to both far-zone and close-range monostatic radar. It refocuses the system point-spread function (PSF) to any range location, taking into account both magnitude and phase changes. The approach can be applied with any Fourier-based imaging algorithm utilizing the Lippmann–Schwinger equation as the underlying scattering model. Here, it is validated through examples based on simulated and measured data where the images are reconstructed with quantitative microwave holography (QMH). QMH employs measured PSFs to achieve quantitative imaging in real-time. The proposed range-migration method is applicable with measured PSFs, too, leading to reduced system-calibration effort and the ability to focus an image at any desired range.

中文翻译：

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单基地雷达的精确距离偏移，用于基于傅立叶的快速定量图像重建


距离偏移（或距离聚焦）技术广泛应用于光学、声学和微波实时图像重建方法中。它们已成功应用于远场 3D 成像，其中依赖于平面波假设，忽略了采集孔径上的数据幅度变化。然而，平面波假设的精度在近距离成像中很快就会降低，因为近距离成像中幅度变化很大，并且到目标的距离约为距离采样步长。在这里，我们提出了一种提高精度的距离聚焦方法，该方法适用于远区和近距离单基地雷达。它将系统点扩散函数 (PSF) 重新聚焦到任何距离位置，同时考虑幅度和相位变化。该方法可以应用于任何利用李普曼-施温格方程作为基础散射模型的基于傅立叶的成像算法。在这里，通过基于模拟和测量数据的示例对其进行了验证，其中图像是通过定量微波全息术 (QMH) 重建的。 QMH 利用测量的 PSF 来实现实时定量成像。所提出的范围迁移方法也适用于测量的 PSF，从而减少系统校准工作并能够将图像聚焦在任何所需的范围。