We propose and demonstrate a pseudo Fabry–Pérot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are sho...We propose and demonstrate a pseudo Fabry–Pérot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are shown in the simulated transmission spectra, and their positions shift toward higher frequencies when the refractive index of liquid crystal decreases. The measured transmission spectra are consistent with corresponding simulations. Via thermally tuning the refractive index of the filled liquid crystal, the resonant transmission frequencies shift accordingly. The work supplies a novel design for tunable terahertz filters, which would play important roles in terahertz imaging, sensing, high speed communication, and security applications.展开更多
In this work, 4-methoxylcinnamoyl chloride was reacted with a commercial hyperbranched polymer （Boltom-TM H30） to prepare a hyperbranched photosensitive polymer （H30-Ci）. The polymer was characterized by UV absorp...In this work, 4-methoxylcinnamoyl chloride was reacted with a commercial hyperbranched polymer （Boltom-TM H30） to prepare a hyperbranched photosensitive polymer （H30-Ci）. The polymer was characterized by UV absorption spectrum and 1H- NMR spectrum. After processed by Linearly Polarized Polymerization （LPP） method, the spin-coated films of H30-Ci were used as photo-alignment layers to assemble liquid crystal （LC） cells containing nematic liquid crystal （5CB）. The observation by polarized microscope showed that the H30-Ci blended with a linear polymer （BP-AN-Ci） photo-alignment layers could align LC molecules in a very uniform way.展开更多
This paper reports the doping effect of cholesteric liquid crystal 3β-Hydroxy-5-cholestene 3-oleate on polymer solar cells composed of the poly 3-hexyl thiophene and the fullerene derivative.With a doping ratio of 0....This paper reports the doping effect of cholesteric liquid crystal 3β-Hydroxy-5-cholestene 3-oleate on polymer solar cells composed of the poly 3-hexyl thiophene and the fullerene derivative.With a doping ratio of 0.3 wt%,the device achieves an ideal improvement on the shunt resistor and the fill factor.Compared with the reference cell,the power conversion efficiency of the doped cell is improved 24%.The photoelectric measurement and the active layer characterization indicate that the self-assembly liquid crystal can improve the film crystallization and reduce the membrane defect.展开更多
The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave （PSW） in a pressure-vacuum supersonic wind tunnel. It...The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave （PSW） in a pressure-vacuum supersonic wind tunnel. It provides qualitative information mainly concerning the overall flow structure, such as the turbulent boundary layer separation, reattachment locations and the dimensionalities of the flow. Besides, it can also give understanding of the surface streamlines, vortices in separation region and the corner effect of duct flow. Two kinds of crystals with different viscosities are used in experiments to analyze the viscosity effect. Results are compared with schlieren picture, confirming the effectiveness of liquid crystal in flow-visualization.展开更多
Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images o...Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter.The human retina is a thin and multiple layer tissue,and the layer of capillaries less than10 μm in diameter only exists in the inner nuclear layer.The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod＆cone cell surface is tens of micrometers,which varies from person to person.Therefore,determining reasonable capillary layer（CL） position in different human eyes is very difficult.In this paper,we propose a method to determine the position of retinal CL based on the rod＆cone cell layer.The public positions of CL are recognized with 15 subjects from 40 to 59 years old,and the imaging planes of CL are calculated by the effective focal length of the human eye.High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system（LCAOS） validate our method.All of the subjects＇ CLs have public positions from 127 μm to 147 μm from the rod＆cone cell layer,which is influenced by the depth of focus.展开更多
Liquid crystal (LC) alignment is most important in LC devices. In this paper, we quantitatively analyze the LC scalar order parameters on the rubbed surface of an alignment layer. Careful measurement of dichroic infra...Liquid crystal (LC) alignment is most important in LC devices. In this paper, we quantitatively analyze the LC scalar order parameters on the rubbed surface of an alignment layer. Careful measurement of dichroic infrared absorbance is performed. The result gives the evidence that the order parameter of LC just on the rubbed alignment film is only 1/3-1/2 that in the LC bulk.展开更多
With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period w...With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period was about 670 nm.The quartz slides covered with SRG films were assembled to liquid crystal (LC) cell to study the LC alignment behavior.Homogeneous liquid crystal alignment was observed in the surface relief gratings regions of the LC cell.Alignment of LC molecules was monitored by measuring the transmittance passing through the cell between crossed polarizers as a function of the angle of the cell rotating around the experiment optical axis.The transmittance changed periodically with a regular 90° separation of the rotational angle and the pretilt angle of the cell was found to be 3.2°.This alignment technique could have useful applications in the future LC displays.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11304151,61490714,61435008,and 61575093)the Ph.D.Programs Foundation of the Ministry of Education of China(No.20120091120020)the Fundamental Research Funds for the Central Universities(Nos.021314380020 and 021314380023)
文摘We propose and demonstrate a pseudo Fabry–Pérot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are shown in the simulated transmission spectra, and their positions shift toward higher frequencies when the refractive index of liquid crystal decreases. The measured transmission spectra are consistent with corresponding simulations. Via thermally tuning the refractive index of the filled liquid crystal, the resonant transmission frequencies shift accordingly. The work supplies a novel design for tunable terahertz filters, which would play important roles in terahertz imaging, sensing, high speed communication, and security applications.
基金the National Natural Science Foundation of China (No. 50103005)Thanks for Professor Shi Wenfang of University of Science and Technology of China to supply the hyperbranched polymer(H30).
文摘In this work, 4-methoxylcinnamoyl chloride was reacted with a commercial hyperbranched polymer （Boltom-TM H30） to prepare a hyperbranched photosensitive polymer （H30-Ci）. The polymer was characterized by UV absorption spectrum and 1H- NMR spectrum. After processed by Linearly Polarized Polymerization （LPP） method, the spin-coated films of H30-Ci were used as photo-alignment layers to assemble liquid crystal （LC） cells containing nematic liquid crystal （5CB）. The observation by polarized microscope showed that the H30-Ci blended with a linear polymer （BP-AN-Ci） photo-alignment layers could align LC molecules in a very uniform way.
基金Project supported by the National Natural Science Foundation of China(Grant No.61540016)
文摘This paper reports the doping effect of cholesteric liquid crystal 3β-Hydroxy-5-cholestene 3-oleate on polymer solar cells composed of the poly 3-hexyl thiophene and the fullerene derivative.With a doping ratio of 0.3 wt%,the device achieves an ideal improvement on the shunt resistor and the fill factor.Compared with the reference cell,the power conversion efficiency of the doped cell is improved 24%.The photoelectric measurement and the active layer characterization indicate that the self-assembly liquid crystal can improve the film crystallization and reduce the membrane defect.
文摘The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave （PSW） in a pressure-vacuum supersonic wind tunnel. It provides qualitative information mainly concerning the overall flow structure, such as the turbulent boundary layer separation, reattachment locations and the dimensionalities of the flow. Besides, it can also give understanding of the surface streamlines, vortices in separation region and the corner effect of duct flow. Two kinds of crystals with different viscosities are used in experiments to analyze the viscosity effect. Results are compared with schlieren picture, confirming the effectiveness of liquid crystal in flow-visualization.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174274,11174279,61205021,11204299,61475152,and 61405194)
文摘Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter.The human retina is a thin and multiple layer tissue,and the layer of capillaries less than10 μm in diameter only exists in the inner nuclear layer.The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod＆cone cell surface is tens of micrometers,which varies from person to person.Therefore,determining reasonable capillary layer（CL） position in different human eyes is very difficult.In this paper,we propose a method to determine the position of retinal CL based on the rod＆cone cell layer.The public positions of CL are recognized with 15 subjects from 40 to 59 years old,and the imaging planes of CL are calculated by the effective focal length of the human eye.High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system（LCAOS） validate our method.All of the subjects＇ CLs have public positions from 127 μm to 147 μm from the rod＆cone cell layer,which is influenced by the depth of focus.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos.19974046, 59973020)the Science Foundation of Jilin Province (20010579) "Hundred-People Plan" of the Chinese Academy of Sciences ([1999]0359).
文摘Liquid crystal (LC) alignment is most important in LC devices. In this paper, we quantitatively analyze the LC scalar order parameters on the rubbed surface of an alignment layer. Careful measurement of dichroic infrared absorbance is performed. The result gives the evidence that the order parameter of LC just on the rubbed alignment film is only 1/3-1/2 that in the LC bulk.
文摘With interfering illumination of Ar++ laser beams (488 nm),surface relief gratings (SRGs) were photo-inscribed on epoxy-based azo polymer (BP-AZ-CN) films.The modulation depth was about 160 nm and the spatial period was about 670 nm.The quartz slides covered with SRG films were assembled to liquid crystal (LC) cell to study the LC alignment behavior.Homogeneous liquid crystal alignment was observed in the surface relief gratings regions of the LC cell.Alignment of LC molecules was monitored by measuring the transmittance passing through the cell between crossed polarizers as a function of the angle of the cell rotating around the experiment optical axis.The transmittance changed periodically with a regular 90° separation of the rotational angle and the pretilt angle of the cell was found to be 3.2°.This alignment technique could have useful applications in the future LC displays.
