Snapshot imaging Mueller matrix polarimeter using modified Savart polariscopes.

We present a snapshot imaging Mueller matrix polarimeter using modified Savart polariscopes (MSP-SIMMP). The MSP-SIMMP contains both the polarizing optics and the analyzing optics encoding all Mueller matrix components of the sample into the interferogram by the spatial modulation technique. An interference model and the methods of reconstruction and calibration are discussed. To demonstrate the feasibility of the proposed MSP-SIMMP, the numerical simulation and the laboratory experiment of a design example are presented. The remarkable advantage of the MSP-SIMMP is easy to calibrate. Moreover, compared with conventional imaging Mueller matrix polarimeters with rotating parts, the advantage of the proposed instrument is simple, compact, snapshot-enabled, and stationary (no moving parts).

Calibration of spatially modulated snapshot imaging polarimeter based on phase-shift interferometry.

The snapshot imaging polarimeters (SIPs) using spatial modulation have gained increasing popularity due to their capability of obtaining all four Stokes parameters in a single measurement. However, the existing reference beam calibration techniques cannot extract the modulation phase factors of the spatially modulated system. In this paper, a calibration technique based on a phase-shift interference (PSI) theory is proposed to address this issue. The proposed technique can accurately extract and demodulate the modulation phase factors through measuring the reference object at different polarization analyzer orientations and performing a PSI algorithm. Using the snapshot imaging polarimeter with modified Savart polariscopes as an example, the basic principle of the proposed technique is analyzed in detail. Subsequently, the feasibility of this calibration technique was demonstrated by a numerical simulation and a laboratory experiment. This work provides a different perspective for the calibration of a spatially modulated snapshot imaging polarimeter.

Demodulation of polarization information for a spatially modulated snapshot imaging polarimeter based on the coherent demodulation theory.

The snapshot imaging polarimeter (SIP) using spatial modulation can obtain all the Stokes parameters of the target through a single measurement. During demodulating of the polarization information of the target, the reference light calibration method is generally used, including a bandpass filter. In this work, a method to demodulate the target polarization information is proposed, which is based on the coherence demodulation theory. Additionally, this method includes a multiplier and a low-pass filter. Taking a spatially modulated SIP using modified Savart polariscopes as an example, a detailed theoretical analysis of the method is derived, and the computer simulation and experiments are carried out to verify the method's feasibility. To the best of our knowledge, this work provides a novel method for demodulating polarization information of spatially modulated SIPs.

Precise spectrum reconstruction of the Fourier transforms imaging spectrometer based on polarization beam splitters.

A method was proposed to precisely reconstruct the spectrum from the interferogram taken by the Fourier transform imaging spectrometer (FTIS) based on the polarization beam splitters. Taken the FTISs based on the Savart polariscope and Wollaston prism as examples, the distorted spectrums were corrected via the proposed method effectively. The feasibility of the method was verified via simulation. The distorted spectrum, recovered from the interferogram taken by the polarization imaging spectrometer developed by us, was corrected.

Empirical mode decomposition based background removal and de-noising in polarization interference imaging spectrometer.

Based on empirical mode decomposition (EMD), the background removal and de-noising procedures of the data taken by polarization interference imaging interferometer (PIIS) are implemented. Through numerical simulation, it is discovered that the data processing methods are effective. The assumption that the noise mostly exists in the first intrinsic mode function is verified, and the parameters in the EMD thresholding de-noising methods is determined. In comparison, the wavelet and windowed Fourier transform based thresholding de-noising methods are introduced. The de-noised results are evaluated by the SNR, spectral resolution and peak value of the de-noised spectrums. All the methods are used to suppress the effect from the Gaussian and Poisson noise. The de-noising efficiency is higher for the spectrum contaminated by Gaussian noise. The interferogram obtained by the PIIS is processed by the proposed methods. Both the interferogram without background and noise free spectrum are obtained effectively. The adaptive and robust EMD based methods are effective to the background removal and de-noising in PIIS.

Static hyperspectral imaging polarimeter for full linear Stokes parameters.

A compact, static hyperspectral imaging linear polarimeter (HILP) based on a Savart interferometer (SI) is conceptually described. It improves the existing SI by replacing front polarizer with two Wollaston prisms, and can simultaneously acquire four interferograms corresponding to four linearly polarized lights on a single CCD. The spectral dependence of linear Stokes parameters can be recovered with Fourier transformation. Since there is no rotating or moving parts, the system is relatively robust. The interference model of the HILP is proved. The performance of the system is demonstrated through a numerical simulation, and the methods for compensating the imperfection of the polarization elements are described.

Static polarization-difference interference imaging spectrometer.

A static polarization-difference imaging spectrometer is conceptually described and demonstrated through experiment. It consists of a Wollaston prism, a Savart polariscope, a linear analyzer, and a CCD camera. This design improves the existing polarization-difference system by eliminating its moving parts and obtaining the spectral variation of the polarization state, and making the system more compact and robust. After simultaneously acquiring two sequential interference images corresponding to two orthogonal polarization states, the hyperspectral images of the states can be reconstructed, respectively. The use of uniaxial birefringent crystal can widen the detectable spectral region.