Imaging at terahertz frequencies has recently received considerable attention because many materials are semitransparent to THz waves. The principal challenge that impedes a widespread use of THz imaging is the slow acquisition time of a conventional point-by-point raster scan. In this work, we present a theoretical formulation and an experimental demonstration of a novel technique for fast compressionless terahertz imaging based on broadband Fourier optics. The technique exploits k-vector/frequency duality in Fourier optics that allows the use of a single-pixel detector to perform angular scans along a circular path, while the broadband spectrum is used to scan along the radial dimension in Fourier domain. The proposed compressionless image reconstruction technique (hybrid inverse transform) requires only a small number of measurements that scales linearly with an image’s linear size, thus promising real-time acquisition of high-resolution THz images. Additionally, our imaging technique handles equally well and on an equal theoretical footing amplitude contrast and phase contrast images, which makes this technique useful for many practical applications. A detailed analysis of the technique’s advantages and limitations is presented, and its place among other existing THz imaging techniques is clearly identified.

中文翻译：

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利用k空间/频率对偶实现实时太赫兹成像

由于许多材料对于太赫兹波都是半透明的，因此以太赫兹频率成像最近受到了相当大的关注。阻碍太赫兹成像广泛使用的主要挑战是常规点对点光栅扫描的缓慢采集时间。在这项工作中，我们提出了一种基于宽带傅立叶光学的快速无压缩太赫兹成像新技术的理论表述和实验演示。该技术利用傅立叶光学中的k矢量/频率对偶性，允许使用单像素检测器沿圆形路径执行角度扫描，而宽带光谱用于在傅立叶域中沿径向进行扫描。提出的无压缩图像重建技术（混合逆变换）仅需要少量的测量即可随图像的线性尺寸线性缩放，因此有望实现高分辨率THz图像的实时采集。此外，我们的成像技术在同等的理论基础上可以处理良好的幅值振幅对比和相位对比图像，这使该技术可用于许多实际应用。对该技术的优点和局限性进行了详细分析，并明确了其在其他现有THz成像技术中的位置。我们的成像技术在同等的理论基础上可以很好地处理振幅对比和相位对比图像，这使该技术可用于许多实际应用。对该技术的优点和局限性进行了详细分析，并明确了其在其他现有THz成像技术中的位置。我们的成像技术在同等的理论基础上可以很好地处理振幅对比和相位对比图像，这使该技术可用于许多实际应用。对该技术的优点和局限性进行了详细分析，并明确了其在其他现有THz成像技术中的位置。