Speckle-based hyperspectral imaging combining multiple scattering and compressive sensing in nanowire mats

Area of Science:

• Optics and Photonics
• Materials Science
• Spectroscopy

Background:

• Monochrome imaging cameras lack inherent spectral information encoding capabilities.
• Hyperspectral imaging and wavelength multiplexing are crucial for advanced optical applications.
• Existing spectrometers can be bulky and complex, limiting their integration in compact systems.

Purpose of the Study:

• To demonstrate a novel method for encoding spectral information onto monochrome cameras.
• To develop a highly compact and sensitive spectrometer.
• To explore the use of disordered materials for spectral information retrieval.

Main Methods:

• Utilizing the complex spatiospectral response of a disordered semiconductor nanowire mat.
• Leveraging strong, diffuse light scattering to generate distinct speckle patterns for different wavelengths.
• Employing a microlens array for spatial multiplexing and simultaneous imaging of speckle patterns.
• Comparing the performance of various information retrieval algorithms, including compressive sensing.

Main Results:

• Achieved retrieval of discrete wavelengths over a wide spectral range with nanometer sensitivity.
• Demonstrated a spectrometer with micrometer thickness.
• Showcased spatial multiplexing capabilities for simultaneous multi-speckle imaging.
• Identified compressive sensing as an efficient algorithm for reconstructing spectral information, even in noisy conditions with limited measurements.

Conclusions:

• Disordered semiconductor nanowire mats can function as highly compact spectrometers.
• The spatiospectral response of these materials enables efficient spectral encoding onto monochrome cameras.
• Compressive sensing offers a robust method for spectral information retrieval in this system, paving the way for advanced hyperspectral imaging applications.