Direct hyperspectral dual-comb imaging

Abstract

Even though dual-comb-based systems are employed almost routinely nowadays in an ever-increasing number of applications, an efficient combination of this effective technique with an imaging arrangement, which would undoubtedly revolutionize hyperspectral imaging, had not yet been demonstrated. Here we present, to our knowledge, the first hyperspectral dual-comb imaging system in which interferograms are directly detected by a video camera. The system, based on a dual-comb scheme capable of consistently generating interferograms at a rate of 1 Hz and below, combines fast hyperspectral imaging with unprecedented optical resolution and fully multiplex operation. Various proof-of-principle experiments demonstrating hyperspectral imaging of molecular resonances have proved that the direct hyperspectral dual-comb imaging method presented here is capable of characterizing a scene with super-fine resolution in a narrow optical span within 1 s.

1 GHz dual-comb spectrometer for fast and broadband measurements

“…This spectral coverage is then only limited by the multiheterodyne detector and the spectral bandwidth of the combs. On the other hand, achieving a high compression factor enables the use of low-bandwidth heterodyne detectors, as recently demonstrated in dual-comb hyperspectral imaging 28,39 and photoacoustic dual-comb spectroscopy 29,40 .…”

Hyperspectral terahertz imaging with electro-optic dual combs and a FET-based detector

“…The architecture presented here can be configured to generate and detect THz combs in a frequency range that goes from a few tens of GHz up to roughly 1.2 THz with freely adjustable optical resolution (down to a single Hz 22 ) and span, exceptional simplicity and an inherently high mutual coherence that enables integration times of up to few hundreds of a second without active stabilization. The main limitation of the current system is evidently the long time needed for the acquisition of the hypercube; nevertheless, recent dual-comb developments promise to overcome current technological challenges to consistently shrink acquisition times to a single second in the next few years 37 , 38 . Besides this, we plan to incorporate spectral processing and classification to the next versions of the system for the identification and quantification of analytes with distinctive absorption spectrum 39 .…”

Improving Resolution of Dual-Comb Gas Detection Using Periodic Spectrum Alignment Method

“…DCS introduces a second local oscillator (LO) comb with slightly different repetition frequency difference to replace the dispersion device in VIPA or mechanical scanning components in FTS. Due to the unique capability of obtaining high resolution, high sensitivity, broad spectral range, and fast measurement speed simultaneously, DCS has drawn considerable attention since its first implementation [ 12 ] and brought significant improvement for applications such as molecular absorption spectroscopy [ 13 ], coherent anti-Stokes Raman spectroscopy [ 14 ], multidimensional spectroscopy [ 15 ], time-resolved spectroscopy [ 16 ], ellipsometry [ 17 ], strain sensors [ 18 ], hyperspectral imaging [ 19 ], and ranging [ 20 , 21 ].…”