Ghost imaging, based on single-pixel detection and multiple pattern illumination, is a crucial investigative tool in difficult-to-access wavelength regions. In the terahertz domain, where high-resolution imagers are mostly unavailable, ghost imaging is an optimal approach to embed the temporal dimension, creating a “hyperspectral” imager. In this framework, high resolution is mostly out of reach. Hence, it is particularly critical to developing practical approaches for microscopy. Here we experimentally demonstrate time-resolved nonlinear ghost imaging, a technique based on near-field, optical-to-terahertz nonlinear conversion and detection of illumination patterns. We show how space–time coupling affects near-field time-domain imaging, and we develop a complete methodology that overcomes fundamental systematic reconstruction issues. Our theoretical-experimental platform enables high-fidelity subwavelength imaging and carries relaxed constraints on the nonlinear generation crystal thickness. Our work establishes a rigorous framework to reconstruct hyperspectral images of complex samples inaccessible through standard fixed-time methods.

中文翻译：

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非线性鬼影成像的高光谱太赫兹显微镜

基于单像素检测和多图案照明的重影成像是难以访问的波长区域中的重要调查工具。在太赫兹域中，高分辨率成像器几乎不可用，重影成像是嵌入时间维的最佳方法，可创建“高光谱”成像器。在这种框架下，高分辨率几乎是遥不可及的。因此，开发用于显微镜的实用方法尤为关键。在这里，我们通过实验证明了时间分辨的非线性重影，这是一种基于近场，光-太赫兹非线性转换和照明模式检测的技术。我们展示了时空耦合如何影响近场时域成像，并且我们开发了克服基本系统重建问题的完整方法。我们的理论实验平台可实现高保真度的亚波长成像，并对非线性生成晶体厚度进行宽松的约束。我们的工作建立了严格的框架，以重建通过标准的固定时间方法无法访问的复杂样本的高光谱图像。