A zoom system named liquid-filled micro-cylindrical lenses integrating a capillary and a biconvex micro-cylindrical lens in a polydimethylsiloxane (PDMS) substrate is designed, which can achieve continuous changed focal length from 2.675 to 9.012 mm by injecting variable concentrations of glycerol aqueous solution into the capillary. The aberration fan diagrams, root mean square spot radius, peak-to-valley wavefront aberration, and modulation transfer function curves at different zoom configurations of the liquid-filled micro-cylindrical lenses are all analyzed, showing good imaging quality over the whole focal length range. And an anamorphic zoom system for uniform collimated beam is designed putting such two PDMS substrates similar as the Kepler telescope structure. The anamorphic system can realize the zoom shaping function with 1:2 to 2:1 aspect ratio beam conversion without machine movement along optical axis and with no significant aberration. The introduced zoom system is characterized by high image quality, small volume, and a simple and stable structure, providing a design idea for cylindrical lenses with variable focal length.

Integrated polarization focal plane detection imaging has the advantages of small size, high system integration, high mechanical stability and real-time polarization imaging in multiple polarization directions. We have developed a simulation model for back-illuminated mid-wave InAs/GaSb Type-II superlattices (T2SLs) infrared focal plane arrays (FPAs) on-chip integrated polarization grating. The polarization grating is an Al-ZnS double-layer subwavelength grating with antireflection coating, which has a better polarization transmission than a single-layer Al grating with the same deep slot. The effect of different grating parameters on the detector is simulated and optimized by the finite-difference timedomain (FDTD) method, and the results obtained are qualitatively interpreted in a physical sense by the Fabry-Perot-like (F-P-like) resonance theory. The optimized grating has a TM polarization transmittance higher than 92% and extinction ratios greater than 32 dB for wavelengths from 3-5 µm, and is suitable for infrared polarization imaging in the 0°-50°f ield-of-view range. The simulation results can provide theoretical basis and guidance for the design of polarization gratings for mid-infrared monolithic integrated polarization InAs/GaSb T2SLs FPAs.

In this work, the Fourier transform infrared spectroscopy (FTIR) and Terahertz time domain spectra (THz-TDS) were employed to study Pu’er white tea with different oxidation levels by changing the withering time. The strongest absorption peak of 3359 cm-1 in FTIR spectra comes from the proteins and polysaccharides. Several intensity ratios of the characteristic absorption peaks with different oxidation levels were analyzed. The white tea with different oxidation levels can be distinguished from the absorbance of THz-TDS in the range of 0.5–1.5 THz. The refractive index calculated from THz-TDS was between 1.42 and 1.44. Principal component analysis (PCA) using FTIR absorbance data showed that the scattered points of PC1 and PC2 can be well distributed in different districts. Hierarchical cluster analysis (HCA) helped to carry out the clustering results of different white tea samples. The sample with overoxidation level can be distinguished by PCA and HCA using THz-TDS absorbance data. Therefore, FTIR might be a convenient, fast, and nondestructive strategy for identifying white tea with different oxidation levels. THz-TDS combined with some software algorithms can be applied to distinguish the different oxidation-processed tea.