Abstract
We propose a real-time hyperspectral video acquisition system that uses coded slits. Conventional imaging spectrometers usually have scanning mechanisms that reduce the temporal resolution or sacrifice the spatial resolution to acquire spectral information instantly. Recently, computational spectral imaging has been applied to realize high-speed or high-performance spectral imaging. However, the most current computational spectral imaging systems take a long time to reconstruct spectral data cubes from limited measurements, which limits real-time hyperspectral video acquisition. In this work, we propose a new computational spectral imaging system. We substitute the slit in a conventional scanning-based imaging spectrometer with coded slits, which can achieve the parallel acquisition of spectral data and thus an imaging speed that is several times higher. We also apply an electronically controlled translation stage to use different codes at each exposure level. The larger amount of data allows for fast reconstruction through matrix inversion. To solve the problem of a trade-off between imaging speed and image quality in high-speed spectral imaging, we analyze the noise in the system. The severe readout noise in our system is suppressed with S-matrix coding. Finally, we build a practical prototype that can acquire hyperspectral video with a high spatial resolution and a high signal-to-noise ratio at 5 Hz in real time.
Highlights
Imaging spectrometers acquire two-dimensional (2D) spatial and one-dimensional (1D) spectral information from a scene simultaneously, producing three-dimensional (3D) data cubes
One way to achieve scanning-based spectral imaging is to mount a panchromatic camera with a controllable bandpass filter, such as an acousto-optic tunable filter (AOTF) [1] or a liquid crystal tunable filter (LCTF) [2]
We propose a real-time hyperspectral video acquisition system (RHVS) based on coded slits
Summary
Imaging spectrometers acquire two-dimensional (2D) spatial and one-dimensional (1D) spectral information from a scene simultaneously, producing three-dimensional (3D) data cubes. The acquisition of a 3D data cube requires either the movement of the slit or the whole imaging system Such scanning-based imaging spectrometers usually cannot realize real-time spectral video acquisition. To compute xm quickly by matrix inversion in Equation (3) for real-time reconstruction and video acquisition, we need to design the coding matrix S such that all measurement matrixes Sm are full-rank. The S-matrix coding slit can suppress the readout noise in the system and greatly improve the imaging quality to achieve real-time spectral video acquisition. In our high-speed spectral video imaging system, the light intensity is weak and Q is large, meaning the performance gain achieved from using the Hadamard measurement matrix is large. After designing the measurement matrix, we can implement our proposed S-matrix coded slits and build a practical system to validate real-time hyperspectral video acquisition.
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