Spectral imaging technology seamlessly integrates imaging and spectroscopy, two pivotal optical measurement techniques, enabling the capture of scene and target information across a broad spectral range. By leveraging the spectral dimension, it provides insights into the material structure and chemical composition of observed targets. Imaging spectroscopy generates a three-dimensional dataset, combining two-dimensional spatial data with one-dimensional spectral data. This approach not only captures the spatial characteristics of targets but also performs continuous spectral analysis for each resolvable spatial pixel. The integration of imaging and spectroscopy facilitates a higher-dimensional representation of target features, offering a robust and scientifically comprehensive foundation for precise detection, accurate identification, and reliable verification of targets. Consequently, it holds significant application potential in domains such as space exploration, aerial remote sensing, astronomical observation, environmental monitoring, and resource surveying. Advanced spectral techniques form the foundation of imaging spectroscopy, with Fourier transform spectroscopy (FTS) standing out due to its inherent advantages, including multi-channel detection (Fellgett advantage), high throughput (Jacquinot advantage), and high wavenumber precision (Connes advantage). In addition, FTS excels in performance characteristics such as minimal stray light interference, broad free spectral range, high spectral resolution, and high signal-to-noise ratio. Since its inception, FTS has attracted substantial research interest and has become a critical tool for structural analysis and molecular characterization in fields like physics, chemistry, biology, medicine, environmental science, and materials science.

We begin by detailing the optical path configurations and modulation principles of Michelson, Mach-Zehnder, and Sagnac interference structures, highlighting their application in various modulation techniques. The interference imaging principles and data structures of temporal, spatial, and spatiotemporal modulated Fourier transform spectral imaging (FTSI) are then elucidated in alignment with their data acquisition modalities (Fig. 10). A comprehensive review of FTSI’s historical development and current research status is provided, highlighting representative studies that discuss the interference structures employed as well as the resulting spectral and imaging performance. Spatiotemporal modulated FTSI, noted for its static structure and high throughput, represents a primary focus for technological advancement. For example, the Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences has conducted extensive research in this field. Using a step mirror Michelson interferometer, the institute has developed prototypes such as the image-field modulated Fourier transform hyperspectral imager (Fig. 40) and the panoramic bispectral infrared imaging interferometric spectral measurement and inversion instrument (Fig. 41). These innovations are designed to meet the critical demands for real-time, online monitoring and analysis of industrial pollution emissions and emergency safety incidents. Finally, the prospective trajectories of FTSI technology are explored, providing strategic guidance for the selection and design of FTSI instruments tailored to practical applications.

Fourier transform spectral imaging technology, leveraging diverse interference modulation structures and imaging modalities, manifests in multiple implementation forms. Each form offers unique strengths and limitations, necessitating careful selection based on specific tasks, operational conditions, and performance expectations. Ultra-precision optics, large-format detectors, high-speed readout circuits, and advanced data processing methods continue to evolve. FTSI instruments are anticipated to adopt architectures that are solid-state, integrated, lightweight, miniaturized, and even micro-miniaturized. Future detection paradigms will likely emphasize static, high-throughput, high-stability, high-reliability, real-time detection, online analysis, and intelligent processing. Expected system enhancements include wider fields of view, broader spectral ranges, higher spatial and spectral resolutions, improved wavenumber accuracy, elevated signal-to-noise ratios, greater sensitivity, and expanded dynamic ranges. These advancements are set to drive transformative influences across a spectrum of military, defense, and civilian applications, solidifying FTSI as a cornerstone technology for the future.