Hyperspectral microscopy is a complicated visualization approach that mixes hyperspectral imaging with state-of-the-art optics and pc software program to allow speedy identification of nanomaterials. Since hyperspectral datacubes are massive, their acquisition is difficult and time-consuming.
Research: Compact and Cheap Hyperspectral Microscopy of 2D Supplies by way of Spectrally Coded Illumination. Picture Credit score: DongIpix/Shutterstock.com
Regardless of the effectivity of spectral scanning in buying hyperspectral datacubes, this method can’t be prolonged to massive numbers of spectral bands due to their low gentle ranges attributable to narrowband filters and mechanical difficulties whereas utilizing massive filter wheels.
Nevertheless, making use of a digital micromirror system (DMD) can circumvent the above drawbacks throughout spectral multiplexing. Using a single DMD avoids the necessity for big filter wheels by selling arbitrary spectral programming.
In an article revealed in The Journal of Bodily Chemistry C, a brightfield DMD-based multiplexing microscope was employed to analyze the two-dimensional (2D) nanomaterials. Moreover, the effectiveness of the DMD-based microscopy was demonstrated by measuring the thickness of few-layer graphene and molybdenum sulfide (MoS2) from their corresponding distinction spectra, which have been later in comparison with their theoretical curves for validation.
Hyperspectral Microscopy to Characterize 2D Supplies
Atomically skinny semiconducting 2D supplies are extensively utilized in nanophotonics, and the excellent optical properties of those 2D supplies play a essential position in lots of functions. Therefore, correct characterization of those 2D supplies is essential to make use of them in system buildings to sample the mandatory electrical contacts.
On this respect, diffraction-limited hyperspectral microscopy serves as a promising software to know these 2D supplies. The restricted diffraction on this microscopy resolves the high-quality characteristic on particular person materials flakes or units.
Hyperspectral microscopy is a spectral imaging modality that may acquire a pattern’s full spectroscopic data and render it in picture type, and is one approach that’s being developed and explored to deal with present analytical challenges for nanoscale 2D supplies.
Hyperspectral microscopy includes the purposeful mixture of a standard high-resolution microscope and spectrometer. The motivation behind growing this method for biomedical functions comes from an curiosity within the organic pattern’s emission or reflectance spectrum, which comprises necessary structural, biochemical, or physiological data.
The distinctive optical properties of 2D supplies are largely depending on the variety of atomic layers. Hyperspectral imaging microscopy exhibits a big potential for speedy and correct thickness mapping.
Hyperspectral Microscopy of 2D Supplies
Within the current examine, the DMD was employed to encode the illumination supply’s spectral content material and overcome the mechanical difficulties of hyperspectral microscopy by way of imaging with a filter wheel. This methodology promoted Hadamard multiplexing within the spectral content material of the pattern, enhancing the sunshine throughput with out affecting the signal-to-noise ratio.
Though utilizing DMD as a programmable spectral filter was beforehand reported, this was the primary work that utilized it to hyperspectral microscopy of nanomaterials. The proposed multiplexing microscope was composed of illumination and an imager. Whereas the illumination aspect was employed with a hyperspectral projector, the imager consisted of a reflective brightfield microscope.
Furthermore, the microscope’s entrance had a biconvex lens that targeted the incident gentle to the again focal airplane of the target to appreciate Koehler’s illumination. Alternatively, the target lens targeted the illumination that was spectrally programmed right down to the pattern and picked up the sunshine mirrored.
The bandwidth and spectral decision of the microscope have been measured utilizing tantalum sulfide (TaS2) since it’s extremely reflective throughout the seen area. The 2 hyperspectral pictures obtained revealed that the topographical options in transmission mode have been greater than in reflection mode.
Measuring the exciton peaks in MoS2 and evaluating them to the theoretical outcome computed utilizing Fresnel’s equations confirmed good settlement with the theoretical spectra for monolayer and bilayer MoS2.
Moreover, the picture of graphite nanosheets on the digicam and the reconstructed hyperspectral picture confirmed areas with a number of spatially separated flakes. The reconstructed picture helped to optically decide the thickness of the flakes at totally different components of the nanosheet.
In abstract, diffraction-limited, quick, large-field-of-view hyperspectral microscopy was demonstrated to distinction spectroscopy. The proposed system might be utilized for characterizing novel units and skinny movie heterostructures. Further modifications to the hyperspectral microscope can allow totally different experiments.
For instance, the pattern, transmission, and reflection hyperspectral imaging could be concurrently achieved with a protracted working distance goal. Hyperspectral imaging of TaS2 with three areas of differing thickness revealed that the topographical options in transmission mode have been greater than in reflection mode.
Alternatively, for the samples that evolve over time, performing hyperspectral video microscopy allowed sampling of each spectral and temporal dimensions. Furthermore, single-pixel imaging might be naturally included into the system by using DMD and a single detector as a substitute of a digicam.
This enabled hyperspectral microscopy within the infrared, which in any other case turns into costly for cameras. The spatial, temporal, and spectral data was captured on a single detector adopted by reconstruction utilizing compressive sensing restoration algorithms.
Giljum, A.T., Ringe, E., Kelly, Okay.F. (2022) Compact and Cheap Hyperspectral Microscopy of 2D Supplies by way of Spectrally Coded Illumination. The Journal of Bodily Chemistry C. https://pubs.acs.org/doi/10.1021/acs.jpcc.2c04018