High-SNR Hyperspectral Night-Vision Image Acquisition with Multiplexing
High-throughput and high-spectral resolution are essential requirements for spectrometers. Conventional slit-based spectrometers require the input slit to be narrow to achieve a reasonable resolution. However, too small a slit cannot gather enough radiation. Many designs have been presented to address these demands. One method (i.e. the Jacquinot advantage) maximised throughput without sacrificing spectral resolution. Over several decades, there have been two important, strongly investigated approaches to improving spectrometre performance. One resulted in the coded-aperture spectrometre (CAS); another resulted in the Fourier transform spectrometre (FTS). CAS replaced the slit with a two-dimensional coded matrix aperture (i.e. mask), introduced to increase light throughput without loss of spectral resolution. After more than half a century of development, the top CAS is the Hadamard transform spectrometre (HTS), whose encoded aperture theories are based on Hadamard matrices. However, there have more recently been some new static, multiplex CASs proposed, based on new mathematical models. In this chapter, we introduce the multiplexing measurements applied to spectrometers for high-SNR data acquisition.