Compact and Inexpensive Hyperspectral Microscopy of 2D Materials via Spectrally Coded Illumination

Hyperspectral microscopy is an optical characterization technique vital to the understanding of nanomaterials. Because hyperspectral datacubes are so large, however, their acquisition is often cumbersome and highly time-consuming. Although acquiring hyperspectral datacubes via spectral scanning is highly efficient, it is difficult to extend this technique to large numbers of spectral bands due to the low light levels caused by narrowband filters and various mechanical difficulties involved in the use of large filter wheels. Both problems can be circumvented, however, by using a DMD to perform spectral multiplexing, as the multiplexing advantage gives high light levels and a single DMD can be used for arbitrary spectral programming, thereby removing the need for large filter wheels. In this work, a DMD-based, brightfield, spectrally multiplexing microscope for investigations of two-dimensional materials is demonstrated. We show the effectiveness of this microscope by rapidly measuring the contrast spectra of few-layer graphene and MoS2 to determine their thickness. The measured contrast spectra are then compared to their theoretical curves for validation.