The airborne cross-track three apertures MilliMeter Wave (MMW) Synthetic Aperture Radar (SAR) side-looking three-Dimensional (3D) imaging is investigated in this paper. Three apertures are distributed along the cross-...The airborne cross-track three apertures MilliMeter Wave (MMW) Synthetic Aperture Radar (SAR) side-looking three-Dimensional (3D) imaging is investigated in this paper. Three apertures are distributed along the cross-track direction, and three virtual phase centers will be obtained through one-input and three-output. These three virtual phase centers form a sparse array which can be used to obtain the cross-track resolution. Because the cross-track array is short, the cross-track resolution is low. When the system works in side-looking mode, the cross-track resolution and height resolution will be coupling, and the low cross-track resolution will partly be transformed into the height uncertainty. The beam pattern of the real aperture is used as a weight to improve the Peak to SideLobe Ratio (PSLR) and Integrated SideLobe Ratio (ISLR) of the cross-track sparse array. In order to suppress the high cross-track sidelobes, a weighting preprocessing method is proposed. The 3D images of a point target and a simulation scene are achieved to verify the feasibility of the proposed method. And the imaging result of the real data obtained by the cross-track three-baseline MMW InSAR prototype is presented as a beneficial attempt.展开更多
The swelling of SU-8 mold is one of the most important factors influencing the dimensional accuracy of a metal mieropart produced by ultra-violet lithography galvanik abformung（UV-LIGA）. The isolation belt struc- tu...The swelling of SU-8 mold is one of the most important factors influencing the dimensional accuracy of a metal mieropart produced by ultra-violet lithography galvanik abformung（UV-LIGA）. The isolation belt struc- ture is usually employed to enhance the dimensional accuracy of electroformed metal mieropart. However, noble metal is wasted because the isolation belt is filled with metal when noble metal mieroparts are fabricated. There- fore, a semi-isolation belt structure is presented to save noble metal. Furthermore, a high current density is also introduced to shorten the eleetroforming time, and thus the dimensional accuracy of electroformed gold micropart is improved by using the electrolyte jet. The experimental results indicate that both the semi-isolation belt and the high current density can help to enhance the dimensional accuracy of electroformed gold micropart. Its dimen- sional error is only 5 μm at the current density of 0. 6 A/dm2 while the semi-isolation belt structure is used.展开更多
目的探讨多层螺旋CT诊断气管憩室的价值。材料与方法收集胸部CT检查发现的气管旁气囊影(paratracheal air cysts,PAC)50例,观察PAC位置、形态、大小及其与气管间关系。比较PAC与气管间通关系常规横断位与MPR及VR显示差异,采用χ2检验进...目的探讨多层螺旋CT诊断气管憩室的价值。材料与方法收集胸部CT检查发现的气管旁气囊影(paratracheal air cysts,PAC)50例,观察PAC位置、形态、大小及其与气管间关系。比较PAC与气管间通关系常规横断位与MPR及VR显示差异,采用χ2检验进行统计学分析。结果 50例PAC均在气管右侧,位于T1-3胸腔入口平面;形态以类圆、椭圆及肾形为主,单房37例,多房13例;水平直径:0.4-2.41cm,纵向直径:1.15～4.47cm;PAC与气管间连通关系大致分三类:"窗"型相通、含气细管相连及潜在细管相连;常规横断位明确显示连通关系21例(42%),MPR及VR显示37例(74%)(χ2=12.55,p<0.05)。CTVE显示局部气管内表面凹陷(17处)及小孔(18处)。结论 MSCTMPR及VR显示大多数PAC与气管间的空间连接关系,对诊断气管憩室具有重要意义,但有一定限度。展开更多
[目的]三维重建观测骨骺环和颈神经、钩状突毗邻关系,指导单孔分体内镜切除部分钩状突对颈神经减压。[方法]建立33例神经根型颈椎病三维模型,测量C3/4~C7T1骨骺环后缘最低点分别至钩状突尖部所在矢状面颈神经前缘前后距离(anterior and ...[目的]三维重建观测骨骺环和颈神经、钩状突毗邻关系,指导单孔分体内镜切除部分钩状突对颈神经减压。[方法]建立33例神经根型颈椎病三维模型,测量C3/4~C7T1骨骺环后缘最低点分别至钩状突尖部所在矢状面颈神经前缘前后距离(anterior and posterior distance of anterior margin of cervical nerve,APDACN)及下缘垂直距离(vertical distance of inferior margin of cervical nerve,VDIMCN)、硬脊膜外侧缘左右距离(left and right distance of lateral border of dure mater,LRDLDM)、颈神经起点上缘垂直距离(vertical distance of superior margin of cervical nerve start point,VDSCNP)、颈神经起点下缘垂直距离(vertical distance of inferior margin of cervical nerve start point,VDICNP)、椎弓根峡部外侧缘前后距离(anterior and posterior distance of lateral border of isthmus of pedicle,APDLIP)、颈神经外展角(abductor angle of cervical nerve,AACN)及前倾角(anterior inclination angle of cervical nerve,AICN)。[结果]随节段降低,矢状面APDACN无显著变化(P>0.05);VDIMCN、VDSCNP、VDICNP、AACN和AICN显著增加(P<0.05),LRDLDM和APDLIP显著减少(P<0.05)。相应节段APDACN、VDIMCN、LRDLDM、VDSCNP、VDICNP、APDLIP、AACN和AICN男女之间的差异均无统计学意义(P>0.05);相应节段左右侧之间上述指标的差异亦均无统计学意义(P>0.05)。主要节段参数(C5/6)APDACN、VDIMCN、LRDLDM、VDSCNP、VDICNP、APDLIP、AACN、AICN与年龄及BMI均无显著相关性(P>0.05)。[结论]随颈椎节段下降,骨骺环后缘最低点为标志的VDIMCN、VDSCNP、VDICNP、AACN和AICN增大,而LRDLDM和APDLIP减少,相同节段上述指标男性与与女性之间,左与右侧间的差异均不明显。展开更多
The depth ranges of typical implementations of Fourier domain optical coherence tomography （FDOCT）, including spectral domain OCT （SDOCT） and swept source OCT （SSOCT）, are limited to several millimeters. To exte...The depth ranges of typical implementations of Fourier domain optical coherence tomography （FDOCT）, including spectral domain OCT （SDOCT） and swept source OCT （SSOCT）, are limited to several millimeters. To extend the depth range of current OCT systems, two novel systems with ultralong depth range were developed in this study. One is the orthogonal dispersive SDOCT （OD-SDOCT）, and the other is the recirculated swept source （R-SS） interferometer/OCT. No compromise between depth range and depth resolution is required in both systems. The developed OD-SDOCT system realized the longest depth range （over 100 mm） ever achieved by SDOCT, which is ready to be modified for depth-encoded parallel imaging on multiple sites. The developed R-SS interferometer achieved submicron precision within a depth range of 30mm, holding potential in real-time contact-free on-axis metrology of complex optical sys- tems.展开更多
基金Supported by the National Basic Research Program (973) of China (No. 2009CB72400)
文摘The airborne cross-track three apertures MilliMeter Wave (MMW) Synthetic Aperture Radar (SAR) side-looking three-Dimensional (3D) imaging is investigated in this paper. Three apertures are distributed along the cross-track direction, and three virtual phase centers will be obtained through one-input and three-output. These three virtual phase centers form a sparse array which can be used to obtain the cross-track resolution. Because the cross-track array is short, the cross-track resolution is low. When the system works in side-looking mode, the cross-track resolution and height resolution will be coupling, and the low cross-track resolution will partly be transformed into the height uncertainty. The beam pattern of the real aperture is used as a weight to improve the Peak to SideLobe Ratio (PSLR) and Integrated SideLobe Ratio (ISLR) of the cross-track sparse array. In order to suppress the high cross-track sidelobes, a weighting preprocessing method is proposed. The 3D images of a point target and a simulation scene are achieved to verify the feasibility of the proposed method. And the imaging result of the real data obtained by the cross-track three-baseline MMW InSAR prototype is presented as a beneficial attempt.
基金Supported by the National Natural Science Foundation of China(91023018)~~
文摘The swelling of SU-8 mold is one of the most important factors influencing the dimensional accuracy of a metal mieropart produced by ultra-violet lithography galvanik abformung（UV-LIGA）. The isolation belt struc- ture is usually employed to enhance the dimensional accuracy of electroformed metal mieropart. However, noble metal is wasted because the isolation belt is filled with metal when noble metal mieroparts are fabricated. There- fore, a semi-isolation belt structure is presented to save noble metal. Furthermore, a high current density is also introduced to shorten the eleetroforming time, and thus the dimensional accuracy of electroformed gold micropart is improved by using the electrolyte jet. The experimental results indicate that both the semi-isolation belt and the high current density can help to enhance the dimensional accuracy of electroformed gold micropart. Its dimen- sional error is only 5 μm at the current density of 0. 6 A/dm2 while the semi-isolation belt structure is used.
文摘目的探讨多层螺旋CT诊断气管憩室的价值。材料与方法收集胸部CT检查发现的气管旁气囊影(paratracheal air cysts,PAC)50例,观察PAC位置、形态、大小及其与气管间关系。比较PAC与气管间通关系常规横断位与MPR及VR显示差异,采用χ2检验进行统计学分析。结果 50例PAC均在气管右侧,位于T1-3胸腔入口平面;形态以类圆、椭圆及肾形为主,单房37例,多房13例;水平直径:0.4-2.41cm,纵向直径:1.15～4.47cm;PAC与气管间连通关系大致分三类:"窗"型相通、含气细管相连及潜在细管相连;常规横断位明确显示连通关系21例(42%),MPR及VR显示37例(74%)(χ2=12.55,p<0.05)。CTVE显示局部气管内表面凹陷(17处)及小孔(18处)。结论 MSCTMPR及VR显示大多数PAC与气管间的空间连接关系,对诊断气管憩室具有重要意义,但有一定限度。
文摘[目的]三维重建观测骨骺环和颈神经、钩状突毗邻关系,指导单孔分体内镜切除部分钩状突对颈神经减压。[方法]建立33例神经根型颈椎病三维模型,测量C3/4~C7T1骨骺环后缘最低点分别至钩状突尖部所在矢状面颈神经前缘前后距离(anterior and posterior distance of anterior margin of cervical nerve,APDACN)及下缘垂直距离(vertical distance of inferior margin of cervical nerve,VDIMCN)、硬脊膜外侧缘左右距离(left and right distance of lateral border of dure mater,LRDLDM)、颈神经起点上缘垂直距离(vertical distance of superior margin of cervical nerve start point,VDSCNP)、颈神经起点下缘垂直距离(vertical distance of inferior margin of cervical nerve start point,VDICNP)、椎弓根峡部外侧缘前后距离(anterior and posterior distance of lateral border of isthmus of pedicle,APDLIP)、颈神经外展角(abductor angle of cervical nerve,AACN)及前倾角(anterior inclination angle of cervical nerve,AICN)。[结果]随节段降低,矢状面APDACN无显著变化(P>0.05);VDIMCN、VDSCNP、VDICNP、AACN和AICN显著增加(P<0.05),LRDLDM和APDLIP显著减少(P<0.05)。相应节段APDACN、VDIMCN、LRDLDM、VDSCNP、VDICNP、APDLIP、AACN和AICN男女之间的差异均无统计学意义(P>0.05);相应节段左右侧之间上述指标的差异亦均无统计学意义(P>0.05)。主要节段参数(C5/6)APDACN、VDIMCN、LRDLDM、VDSCNP、VDICNP、APDLIP、AACN、AICN与年龄及BMI均无显著相关性(P>0.05)。[结论]随颈椎节段下降,骨骺环后缘最低点为标志的VDIMCN、VDSCNP、VDICNP、AACN和AICN增大,而LRDLDM和APDLIP减少,相同节段上述指标男性与与女性之间,左与右侧间的差异均不明显。
文摘The depth ranges of typical implementations of Fourier domain optical coherence tomography （FDOCT）, including spectral domain OCT （SDOCT） and swept source OCT （SSOCT）, are limited to several millimeters. To extend the depth range of current OCT systems, two novel systems with ultralong depth range were developed in this study. One is the orthogonal dispersive SDOCT （OD-SDOCT）, and the other is the recirculated swept source （R-SS） interferometer/OCT. No compromise between depth range and depth resolution is required in both systems. The developed OD-SDOCT system realized the longest depth range （over 100 mm） ever achieved by SDOCT, which is ready to be modified for depth-encoded parallel imaging on multiple sites. The developed R-SS interferometer achieved submicron precision within a depth range of 30mm, holding potential in real-time contact-free on-axis metrology of complex optical sys- tems.
