  We present a robust high signal-to-noise ratio (SNR) snapshot multiplex
spectrometer with sub-Hadamard-S matrix coding. We demonstrated for the first
time that the sub-Hadamard-S matrix coding could provide comparable SNR
improvement with Hadamard-S matrix in Hadamard transform spectrometer (HTS).
Normally, HTS should change the coding mask to obtain a reasonable spectrum
result, causing unexpected time-consuming. An extra imaging path to collect the
light intensity of the aperture is added in this paper. Both light intensity of
the aperture and overlapped spectra are captured within one shot, turning
Hadamard-S matrix coding into sub-Hadamard-S matrix coding. Simulations and
experiments show that the proposed method could obtain comparable SNR
improvement with the traditional HTS, maintaining snapshot.
