Chenling Jia

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.

Photo-patternable GeO 2 -contained organic-inorganic hybrid sol-gel films for photonic applications

Photo-patternable GeO(2)-contained organic-inorganic hybrid films, which can be used for the low cost and mass production of integrated photonic circuits, were synthesized by combining a low-temperature sol-gel process with a spin-coating technique. Optical waveguide properties and photochemical activities of the hybrid sol-gel films were characterized and monitored by a prism coupling technique and a Fourier transform infrared spectroscopy. Advantages for fabrication of ridge structures based on the hybrid films were demonstrated by one-step spin-coating process followed by direct ultraviolet light irradiation. The results indicate that the as-prepared photo-patternable hybrid materials have great applicability for the fabrication of photonic components, and the fabrication process has the advantages of cost-effect and very short processing time over inorganic materials patterning methods.

Snapshot full-Stokes imaging spectropolarimetry based on division-of-aperture polarimetry and integral-field spectroscopy

Snapshot imaging spectropolarimetry is emerging as a powerful tool for mapping the spectral dependent state of polarization across most of scenarios (stable and variable), owing to its capability of real-time parallel acquisition. In this paper, two schema of snapshot full-Stokes imaging polarimeters (SFSIP) based on division-of-aperture polarimetry are presented firstly. In compliance with the definition of Stokes parameters, the first SFSIP consists of three Wollaston prisms with superior extinction ratio and simultaneously measures six polarimetric intensities (I0, I90, I45, I135, IL and IR) of scene. However, the spatial resolution of each polarimetric image only occupy one-six of detector. To increase the spatial resolution, the second SFSIP comprises a optimal four-quadrant polarization array and a pyramid prism is used to simultaneously acquire four polarimetric intensities. Since the optimal four-quadrant polarization array consists of a uniform linear polarizer and four 132º retarders with different azimuth of fast axis, the signal-to-noise ratio for each of the recovered Stokes parameters will be balanced and enhanced. Finally, the four-quadrant polarization array and pyramid prism are integrated into a integral field spectroscopy to construct a snapshot full-Stokes imaging spectropolarimetry (SFSISP). It is used to map the spectral dependent full Stokes parameters across a scene in real time.

Compact and static Fourier transform imaging spectropolarimeters using birefringent elements

Three compact and static birefringent Fourier transform imaging spectropolarimeters are presented. They based on the different combinations of birefringent elements, including Savart polariscope, Wollaston prism, achromatic half-wave plate and quarter-wave plate. After acquiring several interferograms simultaneously for different polarization states with a single CCD, the spectral dependence of polarization states are recovered with Fourier transformation. The interference models are described theoretically, and the performances are demonstrated through numerical simulations and experiments. In contrast to the well-known channeled spectropolarimetry, the most important advantages are that the sampling interferograms have no channel aliasing and directly correspond to the maximum optical path difference of birefringent interferometer. That is say, they can recover the spectral variation of polarization state with the interferometer’s maximum spectral resolution.

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.

Modulation transfer function of a modified spatially modulated imaging interferometer

The modulation transfer function (MTF) is one of the main criteria for judging the image quality of an imaging system. Together with the well-known optical transfer function, the MTF can be regarded as an objective basis reflecting the comprehensive performance of an imaging interferometer. In order to improve the imaging quality of a modified spatially modulated imaging interferometer (MSMII) with large optical path difference, the boundary conditions of an incident ray, at full field of view, along the x and y directions, respectively, are first calculated by the method of prism expansion, and then the exact expression of the pupil function of the MSMII is given. The two-dimensional MTF of the MSMII is obtained by the Fourier transform. Compared with previous studies, this work gives the two-dimensional MTF for the MSMII, and analyzes the effects of various parameters on the MTF. The optimal values of the incident angle i together with the acute angels and are chosen as and , respectively. If so, a high MTF is obtained, i.e. the imaging quality of the MSMII can satisfy the need of detecting upper atmospheric wind fields.