ABSTRACT
An achromatic snapshot full-Stokes imaging polarimeter (ASSIP) that enables the acquisition of 2D-spatial full Stokes parameters from a single exposure is presented. It is based on the division-of-aperture polarimetry using an array of four-quadrant achromatic elliptical analyzers as polarization state analyzer (PSA). The optimization of PSA is addressed for achieving immunity of Gaussian and Poisson noises. An extended eigenvalue calibration method (ECM) is proposed to calibrate the system, which considers the imperfectness of retarder and polarizer samples and the intensity attenuation of polarizer sample. A compact prototype of ASSIP operating over the waveband of 450-650 nm and an optimized calibration setup are developed. The achromatic performance is evaluated at three bandwidths of 10, 25, and 200 nm, respectively. The results show that the prototype with an uncooled CMOS camera works well at each bandwidth. The instrument matrix determined at the narrower bandwidth is more applicable to the wider one. The uncertainties of the calibrated instrument matrices and reconstructed Stokes parameters are improved by using the extended EMC at each bandwidth. To speed up the acquisition of high-contrast images, wide bandwidth along with short exposure time is preferable. The snapshot capability was verified via capturing dynamic scenes.
ABSTRACT
In this Letter, a novel snapshot spectral imaging technique, optically replicating and remapping imaging spectrometer, is presented. It is based on the combination of shifting subimages by a specially designed lenslet array (LA) and filtering subimages by a focal plane continuous variable filter (CVF). The 3D datacube is recovered by just using a simple image remapping process. The use of the LA and the focal plane CVF makes the system compact and low in cost. A handheld proof-of-principle prototype has been built and demonstrated; it covers a wavelength range of 380-860 nm with 80 spectral channels with a spatial resolution of 400×400 pixels.
