Abstract

Snapshot spectral imaging is rapidly gaining interest for remote sensing applications. Acquiring spatial and spectral data within one image promotes fast measurement times, and reduces the need for stabilized scanning imaging systems. Many current snapshot technologies, which rely on gratings or prisms to characterize wavelength information, are difficult to reduce in size for portable hyperspectral imaging. Here, we show that a multicore multimode fiber can be used as a compact spectral imager with sub-nanometer resolution, by encoding spectral information within a monochrome CMOS camera. We characterize wavelength-dependent speckle patterns for up to 3000 fiber cores over a broad wavelength range. A clustering algorithm is employed in combination with l1-minimization to limit data collection at the acquisition stage for the reconstruction of spectral images that are sparse in the wavelength domain. We also show that in the non-compressive regime these techniques are able to accurately reconstruct broadband information.

Highlights

  • Hyperspectral and multispectral imaging are of great importance for acquiring both spatial and spectral information, with applications in environmental sensing to threat detection

  • We have shown that a multicore, multimode fiber bundle can be used as a frequency characterization component in a high-throughput imaging spectrometer for snapshot spatial and spectral measurements with sub-nm wavelength resolution

  • B Spectral correlation bandwidth dependence on fiber length. It was shown by Redding et al that the spectral resolution of a multimode fiber spectrometer is depen

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Summary

Introduction

Hyperspectral and multispectral imaging are of great importance for acquiring both spatial and spectral information, with applications in environmental sensing to threat detection. For many years, scanningbased hyperspectral imaging techniques, such as pushbroom and whiskbroom spectral imaging systems, have been at the forefront of sensing approaches. While they have been widely used in remote sensing applications, scanning systems have many drawbacks, such as the requirement of performing many sequential measurements in order to reconstruct an image. To complex scattering media, multimode fibers are receiving considerable interest for imaging and spectroscopy owing to their high throughput and their use in applications such as remote sensing and endoscopy [26, 27]. By taking advantage of off-the-shelf fiber technology, the potential cost of these specklebased spectrometers can be significantly lower than traditional spectroscopy devices

Fiber imaging spectrometer
Algorithm for spatial and spectral imaging
Wavelength position index
Hyperspectral reconstruction
Discussion
A Number of fiber modes
Conclusions
B Spectral correlation bandwidth dependence on fiber length
C DBSCAN
Findings
D Spatial reconstructions across multiple spectral channels
E Angle dependence of incoming light

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