Snapshot division-of-aperture spectropolarimeter and polarization radiometer

A snapshot spectropolarimeter and a polarization radiometer, utilizing the division-of-aperture principle, have been constructed, calibrated, and tested. The instrument splits the incoming light beam into four sub-beams, which pass through a 2×2 polarizer array and a 2×2 lens array. The energy distribution and polarization information as a function of wavelength are derived from four different spectra measured simultaneously and independently by four spectrometers. Multimode fibers facilitate free-space light coupling. The calibration process for wavelength, radiometry, and polarization is detailed. The operating wavelength ranges from 420 to 700 nm, and the spectral resolution is 3.8 nm at 632.8 nm; the measurement errors for AoLP, DoLP, and DoCP are 0.75°, 2.7%, and 3.7%, respectively. Experimental results with both broadband and narrowband light sources demonstrate the system's spectral resolution and polarization accuracy.