Hadamard transform-based hyperspectral imaging using a single-pixel detector

In this paper, a single-pixel hyperspectral imager is developed based on the Hadamard transformation. The imager’s design, fabrication, signal processing method, and experimental results are discussed. The single-pixel hyperspectral imager works in pushbroom mode and employs both spatial encoding and spectral encoding to acquire the hyperspectral data cube. Hadamard encoding patterns, which are known for their multiplexing advantage to achieve high signal-to-noise ratio (SNR), are used in both encoding schemes. A digital micromirror device (DMD) from Texas Instruments (TI) is used for slow spatial encoding and a resonant scanning mirror in combination with a fixed Hadamard mask is used for fast spectral encoding. In addition, the pushbroom operation can be achieved internally by spatially shifting the location of the Hadamard encoded slit on the DMD, thus the imager is able to acquire 3D data cubes without the need to scan it across the object. Although our experimental results demonstrate the hyperspectral data cubes of various objects over a 450 nm ∼ 750 nm visible spectral range, the proposed imager can be easily configured to be used at other wavelengths due to the single-pixel detection mechanism used.