近日，华中科技大学的刘世元&谷洪刚及其研究团队取得一项新进展。经过不懈努力，他们实现未知探针光谱的超宽带衍射成像。相关研究成果已于2024年8月26日在国际知名学术期刊《光：科学与应用》上发表。

本文提出了一种先进的方法，将CDI的应用范围拓展至未知探针光谱的超宽带照明，有效解决了现有最先进的宽带衍射成像框架所面临的关键挑战。这一进展消除了对探针光谱先验知识的需求，并放宽了对非色散样本的约束，从而显著扩展了光谱带宽，与现有基准相比，带限提高了近四倍。

这一方法不仅可以从未知的照明光谱中单色化宽带衍射图案，还可以确定衍射辐射光谱的压缩采样轮廓。研究人员使用CDI和叠层成像技术对相对带宽超过40%的超宽带超连续谱进行了实验验证，结果显示在超宽带照明下，相干性显著提升，重建保真度提高。

据悉，相干衍射成像（CDI）架构中对相干光谱的严格要求是实现全光谱高效光子利用的主要障碍。迄今为止，几乎所有的宽带计算成像实验都依赖于精确的光谱测量，因为宽带光谱与传统的CDI系统不兼容。

附：英文原文

Title: Ultra-broadband diffractive imaging with unknown probe spectrum

Author: Chen, Chuangchuang, Gu, Honggang, Liu, Shiyuan

Issue&Volume: 2024-08-26

Abstract: Strict requirement of a coherent spectrum in coherent diffractive imaging (CDI) architectures poses a significant obstacle to achieving efficient photon utilization across the full spectrum. To date, nearly all broadband computational imaging experiments have relied on accurate spectroscopic measurements, as broad spectra are incompatible with conventional CDI systems. This paper presents an advanced approach to broaden the scope of CDI to ultra-broadband illumination with unknown probe spectrum, effectively addresses the key challenges encountered by existing state-of-the-art broadband diffractive imaging frameworks. This advancement eliminates the necessity for prior knowledge of probe spectrum and relaxes constraints on non-dispersive samples, resulting in a significant extension in spectral bandwidth, achieving a nearly fourfold improvement in bandlimit compared to the existing benchmark. Our method not only monochromatizes a broadband diffraction pattern from unknown illumination spectrum, but also determines the compressive sampled profile of spectrum of the diffracted radiation. This superiority is experimentally validated using both CDI and ptychography techniques on an ultra-broadband supercontinuum with relative bandwidth exceeding 40%, revealing a significantly enhanced coherence and improved reconstruction with high fidelity under ultra-broadband illumination.

DOI: 10.1038/s41377-024-01581-4

Source: https://www.nature.com/articles/s41377-024-01581-4