We can get the useful information of the targets from the polarization of it. In many cases, the polarization of the target changes with wavelength. Channeled spectropolarimetry (CSP) is a powerful tool to measure the spectrum and polarization simultaneously in one snapshot. However, the resolution of recovered spectrum is severely reduced by the aliasing between channels, which greatly limits the application of CSP. In this paper, aliasing reduction for CSP using Super-resolution technique is presented. An interferometer based on Savart polariscope is implemented and the channeled interferogram on detector is slightly tilted to get the super resolution sampling. We can increase the optical path difference (OPD) largely without the limitation of the detector. The spacing between channels will also increase, which will reduce the aliasing between them. The feasibility of that method is proved by the simulation results.
Recently, the upper atmosphere wind field has attracted increasingly attention of the researchers. The history, status and the future of temporal phase-stepping measurement methods used for upper atmosphere measurement(UAM) are introduced. The traditional four intensities method which is field-widened, achromatic, temperature compensation wind imaging is presented comparatively. This paper mainly expounds the principle and method for three arbitrary phase-stepping measurement methods. Analysis and calculation of the wind temperature and velocity are described emphatically. The more terse and precise measurement method has scientific significance and practical value for physical geography, atmospheric science, environment protection, national defense and national economic construction.
As an important part of the earth, atmosphere plays a vital role in filtering the solar radiation, adjusting the temperature and organizing the water circulation and keeping human survival. The passive atmospheric wind measurement is based on the imaging interferometer technology and Doppler effect of electromagnetic wave. By using the wind imaging interferometer to get four interferograms of airglow emission lines, the atmospheric wind velocity, temperature, pressure and emission rate can be derived. Exploring the multi-functional and integrated innovation of detecting wind temperature, wind velocity and trace gas has become a research focus in the field. In the present paper, the impact factors of the fixed optical path difference(OPD) of near infrared wind imaging interferometer(NIWII) are analyzed and the optimum value of the fixed optical path difference is simulated, yielding the optimal results of the fixed optical path difference is 20 cm in near infrared wave band (the O<sub>2</sub>(a<sup>1</sup>Δg) airglow emission at 1.27 microns). This study aims at providing theoretical basis and technical support for the detection of stratosphere near infrared wind field and giving guidance for the design and development of near infrared wind imaging interferometer.
The basic principle of tempo-spatially mixed modulated Fourier transform imaging spectrometer (FTIS) based on savart plates is outlined. A calibration method of pixel response non-uniformity of charge-coupled device (CCD) camera in such type of instrument is presented. The method which uses column-flat-fields can avoid the influence of interference fringes. The use of polychromatic calibration source can solve the problem of the slant of the fringes in large optical path difference areas. The procedure of calibration experiment and the algorithm of data processing are detailed described. Two groups of relative radiometric calibration coefficient are obtained through the method of least-square. The original images are corrected by using the coefficients to validate its calibration effect. The results indicated that the method can obviously improve the uniformity of pixels and the vignetting artifacts and defect of the instrument can be well corrected. This study provides a theoretical guidance for study, design, modulation, experiment and engineering of FTIS.
The theoretical operation and experimental demonstration of a Fourier-transform Stokes imaging spectropolarimeter are presented. It is composed of two birefringent crystal retarders with equal thickness (the frontal retarder is rotatable) and a Fourier-transform spectrometer based on Savart polariscope. The polarized light enters the spectrometer to create three sets of interferograms, where the spectral Stokes parameters can be calculated and acquired. Compared with previous instruments, the significant advantages of the described sensor are no spatial aliasing in the polarized spectra and it can be used in wider spectral coverage with low cost, ultra-compact size and a simpler common-path configuration.